proc eng p&i d

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Piping and Instrument Diagrams (P&ID’s) Section Overview

Introduction Piping and instrument diagrams (P&ID’s) are schematic representations of all equipment, piping, and process instrumentation and the necessary connectivity and physical interrelationships required for safe and efficient operations consistent with the project scope. This section describes the content and development of P&ID’s.

In This Section

Following is a list of topics in this section.

Topic See page

What is a P&ID? 5j–3

Use of P&ID’s in PPAProject Methodology 5j–5

Staged Development of P&ID’s 5j–10

P&ID Legend and Reference Sheets 5j–13

Format of P&ID Sheets 5j–14

P&ID Index Flowsheet 5j–18

Equipment Shown on P&ID’s 5j–19

Piping Shown on P&ID’s 5j–24

Piping Line and Item Designation 5j–26

Piping Material Specifications 5j–32

Instrumentation Shown on P&ID’s 5j–35

Process Control Elements Shown on P&ID’s 5j–39

Electrical Equipment Shown on P&ID’s 5j–40

Utility Diagrams 5j–41

P&ID Data Extraction—.ALL-file Intelligent P&ID’s

5j–42

Topic See page

Adding Notes to P&ID’s 5j–45

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The Figure items listed below are only available in hard copy. Figures are available in .pdf format for viewing and printing on the Process Engineering web site. Figure 5.J–1: PPALegend Sheet I Figure 5.J–2: PPALegend Sheet II Figure 5.J–3: V-475 P&ID (Example) Figure 5.J–4: V-4700 Crystallizer P&ID (Example) Figure 5.J–5: Utility P&ID (PPAtherm SR-1 Distribution) Figure 5.J–6: Utility P&ID (PPAtherm SR-1 Refrigeration)

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What Is a P&ID?

Introduction P&ID’s show the orderly detailed arrangement of virtually every process component in the facility. They indicate the relative location in the process of each component, how they are interrelated, and special know-how notes regarding installation, operation, or specific design ideas or data.

This schematic shows provisions for normal operations, as well as for startup, shutPPAn, maintenance, and emergency situations.

Purpose The primary purpose of the Piping and Instrument Diagram (P&ID's) is to provide much of the basis for the detailed design of a facility. No symbol on a P&ID should exist without a specification that provides the detail for that component. Information on the P&ID’s must be consistent with the corresponding equipment specification, piping material specification, or instrument/analyzer specification.

P&ID’s are used by the design disciplines during design activities. They can also be used during construction, operator training, startup, operations, and maintenance of the facility. P&ID’s have been described as a “graphical table of contents” for all specifications (equipment, piping, instrument/analyzers, insulation, tracing, tie points).

P&ID’s and the accompanying specifications are the primary means of communication between Process Engineering and the design disciplines. P&ID’s are the key to successful facility design and operation and must be as accurate and complete as possible, without referencing the process function. P&ID’s must be reviewed, checked, and approved by all interested parties before detailed design can begin.

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A P&ID Is … • Language of symbols • Schematic of a process plant that: - Shows connectivity - Identifies in-line piping equipment - Identifies instrumentation - Identifies line sizes and services - Identifies tracing and insulation - Identifies vessels and equipment - Identifies critical elevations and sizes

• Calls for special notes, details, instructions, etc. • Drawing that displays relative orientation and configuration

• Communication tool that serves as: - Basis for detailed design - Guide for construction - Guide for operation and maintenance

• Graphical table of contents to other engineering documents

Continued on next page

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What Is a P&ID?, Continued

A P&ID Is Not …

• Piping isometric or detail drawing • Equipment construction diagram • Scale drawing • Control logic diagram • Document containing process information

Other Considerations

For security reasons, process information and process data are not shown on P&ID’s. That confidential information is shown on the process flowsheets and/or process control documents, including details of how the process is to be operated and controlled. With no process information shown on the P&ID’s, normally P&ID’s can be PPA RESTRICTED instead of PPA CONFIDENTIAL. For a specific project, the appropriate security classification of these documents for use by non-PPA engineering and construction contractors can be determined on a location or project basis. See Chapter 3 of the PPAProject Methodology for Capital and Expense Projects manual for further information on security of project documents.

Although P&ID’s are essentially schematics, the capability to communicate effectively is improved if the relative size and shape of equipment, as well as elevations, are indicated if practical. It is not always practical to show relative size when sizes are so different. Examples would be reactors and seal pots. Physical dimensions outside the equipment should be shown if necessary for process functionality, such as seal legs, pump suction lines, and other lines where either gravity flow or relative elevations are critical for process operability. Physical dimensions for equipment are shown on the equipment specification sheets.

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Use of P&ID's in PPAProject Methodology

Introduction The roles of flowsheets and Piping and Instrument Diagram (P&ID's) in capital projects are significantly changed in PPAProject Methodology. Cost estimates for project authorization normally will be based on the Project Definition Cost Estimate. This cost estimate is based on fully developed process flowsheets well before P&ID’s are completed. Most of the detailed development of P&ID’s will occur after project definition. This topic is intended to clarify the intent of PPAProject Methodology with respect to P&ID’s

Intent of Flowsheets and Piping and Instrument Diagram (P&ID's)

The intent of process flowsheets is to define the chemical process to be built. As used here, process flowsheets include schematics of major equipment, equipment descriptions, material and energy balances, and the Process Control Strategy. Process control might or might not be shown on the same flowsheet that contains the material and energy balance and equipment descriptions. Process issues should be decided upon, developed, and resolved on process flowsheets, not on P&ID’s.

The primary intent of first-pass P&ID’s is to provide additional details to supplement or enhance the production of the Project Definition Cost Estimate.

The primary intent of developed P&ID’s is to document details of the selected chemical process for communication to Design Engineering disciplines for completing the detailed design. Later, P&ID’s provide good documentation for the operating facility.

Objectives of Project Definition

Project definition should adequately define the process and project such that a preliminary or final authorization can be obtained and such that no major process changes should be required after authorization. As a company, PPA wants to minimize engineering costs prior to authorization, and therefore prior to proceeding beyond project definition. Full development of P&ID’s is expensive in terms of resources and money. Therefore, an objective is not to spend the time and money to fully develop P&ID’s until authorization is obtained and the probability of the project being completed is very high.


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Use of P&ID's in PPAProject Methodology, Continued

Work Flow Processes Involving Piping and Instrument Diagram (P&ID's) and Flowsheets

Depending on the stage, other work flow processes are involved in the use and development of P&ID’s.

Stage Description

Project Definition

During the Project Definition Stage, the process description and essential process decisions should be captured on process flowsheets and process control documents. First-pass P&ID’s are developed to the level of details as required by the cost estimating discipline to obtain a Project Definition Cost Estimate. The details associated with the various passes are defined later in this document. P&ID’s should not be needed for process control definition in this stage.

Project Design and Construction

P&ID’s are jointly developed by Process Engineering and Design Engineering to document and communicate process details to the design disciplines. If project definition activities are done at the site, and Process Design and Construction is done in an PPA Design and Construction (DDC) office, the project can be essentially kept at the site until the Project Definition Stage is complete and an authorization is obtained. However, the location of project activities does not define or limit participation. Remember the DDC people will participate in project definition activities at the sites, and site people will participate in project design at DDC. For large projects, final development of P&ID’s will normally be done at DDC. This significant effort on P&ID’s should not be started until all project definition documentation has been completed and project authorization is assured.


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Use of Piping and Instrument Diagram (P&ID's) During Project Definition Stage

The cost estimating function within The PPA Chemical Company has stated that they normally can generate a quantity-based cost estimate for Project Definition for project authorization without having new, fully developed P&ID’s. There are cases where it is necessary for the cost estimating function to have some P&ID information to adequately generate a Project Definition cost estimate. The PPAProject Methodology does not say that P&ID’s are not allowed in project definition. Following are some situations where P&ID’s might be considered during project definition.

Situation Recommendation

Repeat Facilities and Retrofits

Use existing P&ID’s from Technology Centers or existing facilities. Preferably these would be standard P&ID’s as established by the Technology Center. These could be marked up by the project team and serve to help generate the first-pass of the project P&ID’s.

New Technology

New first-pass P&ID’s could be required if the process flowsheets, Process Control Strategy, preliminary plot plan, etc., do not provide adequate detail for cost estimators. Even facilities for a new process will have many unit operations that are well established within PPA. For those unit operations—such as THROX units, distillation columns, batch reactors, etc., P&ID’s from existing facilities or example P&ID’s from Electronic Most Effective Technology Library (EMETL), should be marked up and given to the cost estimators for their needs.

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Special Situations for Partial P&ID Development

One situation that might be encountered is the need for an early air permit that requires flange and valve counts, which requires at least first-pass P&ID’s. In other cases a total project might involve only a portion of an existing facility and limited number of unit operations and flowsheets. The few required P&ID’s will define the project and do not require a significant amount of development time. If the existing technology P&ID’s will require considerable effort to update to current symbology (control valve tags and insulation codes for example), then it may be more cost effective to develop new P&ID’s. Project and Engineering Management might identify other special situations. However, the goal is to minimize the amount of time and money spent on development of P&ID’s prior to the completion of project definition and obtaining the project authorization.


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Definition of First-Pass Piping and Instrument Diagram (P&ID's)

First-pass P&ID’s have two primary purposes. One is to convey information to the cost estimators during project definition, and the other is to provide a starting point for final P&ID’s for the project. Check with the cost estimator to determine specific needs on a given project.

Joint Development of Piping and Instrument Diagram (P&ID's)

In PPAProject Methodology, the detailed development of P&ID’s is a joint effort by Process Engineering and Design Engineering, along with the Manufacturing Representatives. Process Engineering will normally provide initial input to the P&ID’s based on project flowsheets and control strategy. Design Engineering, particularly the piping and instrument/analyzer disciplines, will provide further detail as the P&ID’s reach completion. Further guidance on P&ID development can be found below. Individual work processes for capital projects provide significant additional detail.

Joint Development of Process Control Definition

The general determination of how the process should be operated and controlled (Process Control Strategy) should be accomplished during project definition. The details of the control hardware will be defined in the Project Design and Construction Stage. The Process Control Strategy is developed in a joint effort by Process Engineering, Process Control, Instrument/Analyzer Engineering, and the Manufacturing Representative. Their activities and work products are described in PPAProject Methodology and the respective work processes.

Development of Piping and Instrument Diagram (P&ID's)

The number of passes for development of a P&ID should be minimized to reduce costs and unnecessary and repeated re-evaluations. A summary of the recommended process is shown below. Further detail is under the heading “Staged Development of P&ID’s” later in this section. Development passes should not be confused with the number of passes through process graphics. The pass definition is content or detail related. A cycle to get all the major and secondary lines shown and another cycle to add all of the line balloon data is not two passes.

Pass Description and Timing

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First-Pass These are new P&ID’s based on process flowsheets and/or marked up existing P&ID’s or segments of P&ID’s. Libraries of standard and/or MET P&ID’s from Technology Centers and manufacturing facilities are desirable starting materials. Professional P&ID designers should be able to construct good (and intelligent) first-pass P&ID’s from flowsheets or the other sources mentioned (start between PPAProject Methodology Steps 12.10 and 14.05). The detail or content of first-pass P&ID’s should be an appropriate blend of Process Engineering’s work process for PPAProject Methodology Step 12.10 and 14.05. All of Step 12.10 should be done, while only parts of Step 14.05 will be required for first-pass P&ID’s.


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Second-Pass

First-pass P&ID’s are marked up by the project team with special emphasis on process control and instrumentation. Line diameter sizes, piping material specifications, and specifics regarding types of insulation and tracing are defined and added to P&ID’s (do between PPAProject Methodology Steps 14.05 and 14.09).

Third-Pass Additional equipment detail and feedback from HAZOP studies (Step 14.10) and other designated input and evaluation efforts (Steps 14.13 and 14.14).

Fourth-Pass

Update after Step 14.15.

As-Built Complete after construction completion.

No Changes After Project Definition

The project scope and chemical process should be firmly defined in the Project Definition Stage prior to obtaining the cost estimate (Step 12.19) and authorization. Therefore, no changes should be made to the process flowsheets and no significant changes made in project scope as P&ID’s are developed in the Project Design and Construction Stage.

No Changes After Completion of Piping and Instrument Diagram (P&ID's)

After P&ID’s have been developed and then reviewed in Step 14.15, a no change mind-set should be adopted by the project team for completed P&ID’s. Changes beyond this point can cause significant delays and extra project costs. The project team must make a commitment to no changes on P&ID’s, flowsheets, and project scope. The project team should establish the criteria, procedures, and approvals necessary to make a change when absolutely required for the project.

Staged Development of P&ID’s

Introduction The number of passes for development of the Piping and Instrument Diagram (P&ID's) should be minimized to reduce unnecessary reconsideration and excessive costs. A recommended process is provided in this section. Because of the variety of information sources for P&ID’s and the variety of types of projects, this process might require modification to meet the needs of a particular project. However, this approach is a good starting point for consideration.

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First-Pass Piping and Instrument Diagram (P&ID's)

There are many sources of information for P&ID’s. P&ID’s should be developed based on the process flowsheets for the project. Process engineers or professional P&ID designers should be able to construct a good first-pass P&ID by expanding the process flowsheets for the project from project definition.

Repeat or retrofit projects should start with P&ID’s from existing plants. Ideally, the responsible Technology Center, as well as the manufacturing facilities, should have libraries of standard/MET P&ID’s for their processes. Starting from existing and/or Most Effective Technology (MET) P&ID’s can save time and improve standardization. However, in these cases, care must be taken to ensure that the first-pass P&ID’s are also consistent from the Project Definition Stage and that they utilize current symbology, especially for instrument items and control valve tag numbers.

Following are some items that should be included on the first-pass P&ID’s.

Item Description

A Equipment with tag numbers, main process lines, (those lines that are shown on the process flowsheets), secondary process lines (includes known/hard-piped lines required for startup, shutPPAn, and recycle), and utility lines. Utility headers will be drawn later.

B Title block information.

C Supplier packages shown inside dashed lines.

D Tie points identified but not necessarily numbered.

E Process control equipment, including control valves, EBVs, FBVs, and process control instrumentation from the process control graphic.

F manually-operated isolation and bleed valves (if readily known) and anticipated location of relief devices.

G Line bubbles including preliminary line sizes, and the need for insulation and tracing by Y/N designation (the type of tracing can be shown if it is readily known).

H Generic (stainless steel, monel, Teflon-lined, etc.) piping materials of construction if other than carbon steel and piping pressure class if other than 150 psig or metric equivalent.


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Staged Development of P&ID’s, Continued

I Basic pump installations.

Second-Pass Piping and Instrument Diagram (P&ID's)

The first-pass P&ID’s should be marked up by the project team with special emphasis on completion of process control and instrumentation.

The following items should be included on the second-pass P&ID’s.

Item Description

A Instrument and control hardware specifies.

B Piping material specifications.

C Line bubbles including final line sizes and insulation and tracing codes.

D Equipment nozzle sizes.

E Piping reducers.

F Pump installation details

Third-Pass Piping and Instrument Diagram (P&ID's)

This pass in particular should incorporate feedback from the HAZOP studies (Step 14.10) as well as other designated input and evaluation opportunities (Steps 14.13 and 14.14).

Additional items that should be located on the third-pass P&ID’s are listed below:

Stage Description

A Instrument tag numbers.

B MOD™ process control computer numbers if applicable.

C Control valve sizes and reducers associated with them.

D Relief system sizes where possible.

Fourth-Pass Piping and Instrument Diagram (P&ID's)

In Step 14.15, a thorough project team check of all P&ID’s and specifications is conducted. In particular, the consistency of P&ID’s and specifications must be accomplished.

The fourth-pass P&ID’s should capture all changes resulting from the team check in Step 14.15.

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As-Built Piping and Instrument Diagram (P&ID's)

At the end of the Project Design and Construction Stage, Process Engineering should assemble all process engineering data including as-built P&ID’s as specified in Step 17.11. These will be made a part of the plant operating discipline.

After the plant has demonstrated the desired operating performance, as-built drawings and specifications should be placed in the site maintenance and plant operating archiving systems (Step 21.02). If modifications have been made during startup, Process Engineering should modify the as-built drawings one more time before turning them over to the production plant.

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P&ID Legend and Reference Sheets

Introduction The legend and reference sheets identify the codes and symbols used for the various pieces of information on the Piping and Instrument Diagram (P&ID's).

Format Legend and reference sheets are normally large-size drawings. The first sheet defines all symbols and identifications for piping and general items. The second sheet defines instrumentation identification and symbols. The sheets normally are numbered B1-D00002-Dxxxx and B1-D00003-Dxxxx.

Refer to the example legend and reference sheets, Figures 5.J–1 and 5.J–2 at the end of this section.

Content • A typical line identification is shown graphically and explained.

• Line service designations identify the name or type of fluid flowing in each line. Examples are ‘P’ for process fluid, ‘V’ for vent fluid, and ‘C’ for steam condensate. All code letters used in the package are defined in the line service designation portion of the legend and reference sheets.

• Line sequence numbers are assigned to individual lines. • A line size, consisting of the nominal pipe diameter in inches (or millimeters) and fractions thereof, is shown.

• Each line must be assigned a specification code per the job-related piping material specification.

• Insulation class and type, where required, for each line (or portion thereof) shall be shown immediately below the line identification “balloon” on the right-hand side. (A balloon is an elongated oval—usually 45 mm by 5 mm—used on pipelines to contain the line designation.)

• Tracing type, where required, for each line is shown immediately below the line identification balloon on the left-hand side.

• A list of all piping item symbols used is necessary to clearly define the type of valve, fitting, connection, or other piping component at each point.

• Instrument/analyzer designations, symbols, and explanations are included in the instrumentation legend and reference sheet to identify the instrument and analyzer types used in the facility design.

• A drawing index, number B1-D0001-Dxxxx, listing all drawings, should be included as the first sheet. This index should provide an index cross referencing equipment numbers with P&ID numbers.

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Format of P&ID Sheets

Introduction The standard P&ID format defined below shall be followed at all sites. Refer to the example Piping and Instrument Diagram (P&ID's) in following this section.

Definition of Terms

Following are definitions of some terms used on P&ID’s:

Term Definition

Balloon Elongated ovals, usually 45 mm by 5 mm, used on pipelines to contain the line designation.

Know-how note Two concentric circles with the space between the circles filled in black, 5 mm inside, 6 mm outside, indicating know-how note or job instructions.

Cloud Outline indicating information on something that has changed.

Ghost Piece of equipment shown in dotted lines because it is shown in more than one place on the P&ID’s.

Interface point

Intermediate points where new facilities, being engineered or constructed by one group or agency, will meet facilities being engineered and constructed either another way or by someone else. An interface point might require a tie point.

Tie point Point at which the new facility makes piping contacts with existing facilities.

Item status legend (status bubble)

Symbol indicating the status of a piece of equipment—such as new, existing, relocated, future, or supplier- or owner-supplied. It is usually used to identify exceptions. A status bubble is a ¼-inch circle located next to the equipment bubble.

Contract breaks

Interface lines indicating contract or purchase order scope of work.

Title Block The title block identifies the process plant shown on the P&ID (third line). Do not identify the product name or the chemicals used. An example of title block format:

Plant name BlockProject/ProcessEquipmentDrawing type


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Format of P&ID Sheets, Continued

Drawing Size P&ID’s are B-size drawings (A-size in Europe) with the overall dimensions of 22 inches × 34 inches or 24 inches × 36 inches. A space of 75 mm (3 in.) is reserved along the bottom of the sheet for special instructions and know-how notes. A space of 50 mm (2 in.) is reserved along the sides of P&ID’s for entrance and exit lines.

Crowded Drawings

During their development, P&ID’s contain progressively more and more information. Therefore, one major equipment item shall be normally shown on one sheet. However, a single complex and highly instrumented item can crowd even one sheet. In such cases, a second sheet showing, for example, the instrumentation separately shall be considered. An alternative is to consider breaking the unit into subparts. An example would be to show a reactor and its jacket system separately.

Section Numbers

The process section numbers should be coincident with those on the process flowsheet. If the project uses process sections, the process sections can be numbered in steps of 50 or 100, depending on the size of the project.

Scope of Work Clearly show the scope of work for engineering when possible. Use status bubbles, tie points, interface points, clouds, and boxes, as appropriate, to indicate the scope of the work.

Installation Details

Installation details shown on the legend and reference sheets are examples only. Nonstandard installation details can be shown on every P&ID on which they appear. However, a better way is to use know-how notes to refer to detail drawings. This makes it easier to release details to contractors without having to issue the P&ID’s.


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P&ID Numbering A common method for numbering P&ID’s is to assign a group of drawing sequence numbers to each process section as identified on the index flowsheet. If process sections are assigned on the process flowsheets, the P&ID numbers are within the numbers of these process sections and raised in steps of 2 to 10.

Examples:

• Section 100 = B1-100-xxxxxx • B1-105-xxxxxx , where: B1 = drawing number prefix indicating a P&ID 105 = process section number as shown on index flowsheet xxxxxx = specific project number

• B1-110-xxxxxx through B1-145-xxxxxx or B1-195-xxxxxx • Section 200 = B1-200-xxxxxx • B1-205-xxxxxx • B1-210-xxxxxx through B1-245-xxxxxx or B1-295-xxxxxx

Critical Information

Indicate critical liquid levels, critical equipment elevations, etc., for condensers, reflux drums, and reboilers, etc.

Utility Lines A convention for utility line boxes is to place them at the top of the P&ID where possible (without cluttering the drawing) so utility lines enter or leave the page in a vertical direction. Another convention is to place the utility boxes as close to the utility source or termination point on the graphic as practical.

Utility lines can also be considered to be process lines, using directional lines on the side of the sheet.

Symbology Show correct symbols as shown on the legend and reference sheets and in accordance with the appropriate equipment, instrument/analyzer, or piping material specifications.


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Equipment Tag Identification

There are two conventions in common use for showing equipment tags.

Convention

Description

1 New, existing, future, etc., items shall be identified on each P&ID for equipment, instrument/analyzers, and piping. Use status bubbles to show exceptions. Existing piping, equipment, and instrument/analyzers are to be shown dotted or can be shown as “clouded.” Clouding might be better because it is easier to remove and produce a clean P&ID at the end of the project for facility records. New piping, equipment, and instrument/analyzers are to be shown as solid lines. This also applies to renovation projects. Continue the use of status bubbles and status notes in lower-left corner. Clouds should be identified with a revision triangle to reference the date and reason.

2 According to the Common P&ID Program, the dominant status of the items in a drawing is defined in a default status statement in the lower right-hand corner of the drawing. Any items that differ from the default status are identified by status bubbles. Groups of items sharing a common status can be scoped using item status scoping. Item status scoping consists of a pattern of distinct dashed lines. This is not cloud scoping, which is used only for revisions made on finished and signed P&ID’s. It is not necessary to draw equipment with dashed lines or cross-hatching to indicate a different status, since status bubbles provide this information.

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P&ID Index Flowsheet

Introduction The P&ID index flowsheet schematically shows the interconnections of all major process and utility equipment to provide an overall view of the process on one drawing. The P&ID index flowsheet is the same as the process index flowsheet with all confidential process information removed.

Purpose The purpose of the P&ID index flowsheet is essentially the same as that of the process index flowsheet, but the amount of information that is transmitted to the user is limited. Its use is optional, but it is often considered to be a valuable tool.

Format The P&ID index flowsheet is a normally a large-size drawing. The format shall be the same as used for the process index flowsheet. The P&ID index flowsheet is numbered B1-00004-xxxxxx. An abbreviated P&ID number will be shown on or adjacent to the equipment item. It will indicate the P&ID sheet number where the equipment item can be found.

Content The content shall be essentially the same as found on the process index flowsheet for the project except that all confidential information is removed.

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Equipment Shown on P&ID’s

Introduction All equipment related to the process and utilities within the scope of the project is shown on the Piping and Instrument Diagram (P&ID's) and identified by an assigned equipment number. This equipment number will not identify process functionality. All connections, size, and type are shown, including manways and other access requirements. Insulation and tracing requirements for equipment are shown below the equipment number symbol.

Although most internal details are shown on the equipment specification data sheets, sufficient information should be shown on the P&ID’s to ensure the correct connections to piping and instrumentation. For example, vessel jackets, dip pipes, and agitators should be shown. The vessel registration number and pipe specification code for direct connect instrumentation are also useful items to include on the P&ID next to the equipment item tag. Other optional information can be added, such as the NFPA hazard symbol (diamond) for the contents of a piece of equipment or pipeline.

Equipment Identification

Every piece of equipment shall be identified by the equipment type designation and a unique equipment number, not by process function. Equipment numbers shall correspond to the process section numbers stated on the process flowsheets.

Each driver (for example: motor, turbine) shall have its own equipment identification. It is suggested that each driver equipment number have the same equipment number as the accompanying equipment, but that they have different equipment designation letters. The tag should list the letters first, then the numbers. Refer to Section H of Chapter 5 for a list of commonly used equipment designation letters.

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Equipment Symbols

As much as practical, each equipment outline shall be shown at its relative field elevation and position. The size of each shall be proportional to its actual size in relation to other equipment on that sheet. When applicable, the shape of the equipment outline shall be standard equipment symbols. Following are suggestions for equipment layout:

• Show as relative shape: spheres, tanks, columns, pumps, heat exchangers

• Show with relative orientation: horizontal, vertical, sloped

• Show with relative position: location relative to other equipment (for example: bottoms pump shown at column bottom)

• Show as relative size: size relative to other equipment (for example: pumps usually smaller than associated equipment)

• Duplicate equipment: both pieces are shown fully piped and instrumented

• Equipment status: new, existing, relocated, future, supplier- or owner-furnished


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Equipment Shown on P&ID’s, Continued

Elevations Critical elevations and elevation differences shall be shown adjacent to the equipment. Examples include elevated distillate collection drums designed for gravity flow to storage vessels, low and high liquid levels, elevations above pump suctions, etc. Show floor or structure elevations.

Internals Certain items of internal equipment shall be shown for clarity or other reasons. Examples include bottom, feed, and top trays with their numbers, tank partitions, chimney trays, packed sections of towers, trays with temperature points, baffles, dip tubes, vortex breakers, packed tower internals (supports, distributors, nozzle projections, etc.).

Insulation, Tracing, and Trim

Equipment insulation and tracing is specified below the equipment number symbol in the same manner as indicated for piping lines. Identify trim materials of construction for the equipment. Trim is defined as those parts of a valve body assembly—excluding the valve body, bonnet assembly. And bottom flange—that are exposed and in contact with the line medium usually consisting of, but not limited to, the seat ring, valve plug stem, valve plug, valve plug guide, guide bushing, and cage.

Nozzles All equipment nozzles shall be identified on each piece of equipment by a single square with both the nozzle letter and the nominal size inside the square. The type of connection should be properly represented. When multiple nozzles on heads produce crowding, use tail lines or pointer lines.

Number nozzles starting from the bottom of a piece of equipment going up, and then from left to right horizontally. Refrain from using the letter ‘I’ and the letter ‘O’ because they are often confused with the numbers ‘1’ and ‘0’.

Heat Exchangers

Shell Side Tube Side Inlet A Inlet C Outlet B Outlet D Relief R1 Relief R2 Shell Drain DR1 Head Drain DR2 Shell Vent V1 Head Vent V2


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Nozzles, continued

For example, show nozzles on exchangers as follows:

AX”

RX”

V1X”

V2X” D

X”

CX”

DR1X”

bX”

DR2X”

Vessels

Service Designation Size Inlet A1, A2, A3, etc. as

required Outlet B1, B2, B3, etc. as

required Agitator C 10” minimum Relief R as required

(Consider using nozzle one size larger than relief size. Also, list thrust load on P&ID.)

Manway M 24" minimum Hand-hole H as required Removable Baffle RB (Glass Vessels) 8"

minimum Sample Z 2" Spare S1, S2, S3, etc. 3" or 4"

as required Vent V 2" minimum Level Transmitter L1, L2, L3, etc. 2" with

drip ring Level Trans. w/ 2 taps L1A, L1B lower tap

should be labeled A, and the upper tap labeled B

Level Switch L1, L2, L3, etc. 2” flanged

Pressure P1, P2, P3, etc. 2" for non-plugging service, Otherwise use 3" w/ diaphragm

Press. Trans. w/ 2 taps P1A, P1B lower tap should be labeled A, and the upper tap labeled B

Temperature T1, T2, T3, etc. 2" Jacket Inlet JA1, JA2, JA3, etc. as

required Jacket Outlet JB1, JB2, JB3, etc. as

required Jacket Vent JV1, JV2, JV3, etc. 1"

flanged Jacket Drain JD1, JD2, JD3, etc. 1"

26

flanged


27


Nozzles, continued

For example, show nozzles on vessels as follows:

L1BX”

L1AX”

A1X”

JB1X”

JA2X”

JB2X”

JA1X”

BX”

JD1X”

JD2X”

JVX”

L2X”

A2X”

PX”

VX”

A3X”

DXXXXXYYYY

In instances where two pieces of equipment are connected flange-to-flange with no interconnecting piping (for example: certain reboiler connections to a tower), the matching nozzle sizes on both shall be shown. If two pieces of equipment must be drawn separately for clarity, a line shall connect the appropriate flanges or, if there is a direct connection, dashed lines can be used. All nozzle sizes and letters on P&ID’s must exactly match those on the equipment specifications.


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Blinded Nozzles

All blinded nozzles, including manholes, handholds, inspection ports, spare nozzles, etc., shall be shown. Valves connected to vessels but not in piping lines shall show size and whether blind flanges or threaded connections are used (such as for jacket vents).

Equipment Supports

Equipment supports, legs, and skirts shall be shown if integral and/or if needed for clarity.

Package Units Package units shall be indicated by being enclosed in a dashed box indicating what is and what is not supplied by the supplier as part of the package unit. Each significant part of a package unit should be identified with a proper tag number for tracking and maintenance.

Equipment Requiring Utility Service

All equipment requiring a utility service, including electrical, shall be identified on the P&ID’s. Equipment such as unit space heaters, utility stations, safety showers, etc. can be grouped separately as “utility” P&ID’s. Utility and Process Safety equipment are treated as process equipment, with instrumentation and piping shown. Typically, utility headers are redrawn once detail engineering layouts have been completed. Personnel protection areas should be indicated.

Insulation Insulation shall be shown even on preliminary P&ID’s. Show insulation specifications on vessels and equipment.

Cross-Reference

An index is normally provided that cross-references equipment numbers with P&ID numbers.

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Piping Shown on P&ID’s

Introduction Piping is shown schematically in a logical sequence. The physical arrangement of the piping is not shown on Piping and Instrument Diagram (P&ID's). Piping dimensions, isometrics, and stress considerations will not be shown on the P&ID unless there are overriding process reasons.

What Is A Line?

A line is a piece of pipe, usually between two defined points. Examples include:

• Connection between two pieces of equipment • Connection between a piece of equipment and another line• Connection between two lines • Connection from a piece of equipment or line to a drain or the atmosphere

• Header between two blind flanges or to pipe caps • Connection to or from an in-line analyzer • Line terminating to atmosphere or to a ditch without a

flange

Piping To Be Included

All piping to be installed as a part of the project—plus information required to effectively communicate the connections to existing facilities—should be shown. All items that affect process functionality must be specifically identified. This includes drains, vents, flush connections, steam traps, air vents, reducers, and relief devices. The graphical protocol is to have process lines run horizontally as much as possible. One convention is to have utility lines run vertical as much as possible. Other conventions are to place the utility boxes as close to the utility source or termination point on the graphic as practical or to consider utility lines as process lines, using directional lines on the side of the sheet.

Detailed piping is not shown. Elbows and tees are not indicated on P&ID’s. However, strainers, startup screens, reducers, break-out flanges, etc., should be shown.

If covering and/or tracing is required, the appropriate specifications will also be given. Connections to existing piping or equipment will be identified by the use of tie points and interface points.

Piping connections to equipment and line terminations are shown as flanged or threaded on the P&ID’s, but inter-piping connections will be governed by the applicable piping material specification and might not be shown. Coupled lines, such as with unloading and loading units and switch-overs, can be shown.


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Piping Shown on P&ID’s, Continued

Other Items Specified

All valves, whether process or utility, shall be shown on P&ID’s. Where it is important for the maintenance and operation of the facility, fittings (such as caps and bull plugs) and connections (such as flanged or threaded couplings or unions) are shown on P&ID’s. Standard symbols for various valve types shall be used and are defined on the legend and reference sheet. This is also true for the valve portion of control valves. In that case the location and size of reducers shall also be indicated. For control valves, the body sizes will be added during detailed engineering.

The valve, fitting, or connection specified must be in the piping material specification. Indicate valve item numbers on the P&ID’s if the piping material specification offers a choice. If more than one valve of the same type and size range is in the piping material specification, the first valve listed will be the default choice. If any valve other than the default is to be used, the full V-number of the valve must be shown on the P&ID’s. Special attention should be given to valves in corrosive or hazardous service that are drilled for vent relief.

The sizes and types of valves will be consistent with the line size, service, and piping material specification. Manual valves will be indicated by type. Where multiple choices exist, job instructions must make clear whether the choice will be determined by economics only or whether the Project Manager (or Manufacturing Representative) will decide based on other factors. Normally, the intent is that the P&ID’s, along with the piping material specifications, identify commonly available types and sizes of valves. Unique and unusual valves should be identified as pieces of equipment (specials).

Bleed Valves Bleed valves shall be shown. However, vent and drain valves for line pressure testing are not normally shown.

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Pipeline Numbering

Each pipeline will have a label consisting of a unique identifier, size, and piping material specification code. Each process line shall be identified with a line number that corresponds directly with the P&ID from which it originates and the equipment from which it originates. Existing line numbers might remain when a P&ID is revised or redrawn since they are used in other existing drawings, such as piping drawings.

Number all lines sequentially regardless of process prefix; that is, there is only one line numbered 1, 2, etc., instead of A-1, N-1, … All jacketed lines must have the same number as the main line that is jacketed. For example, if the main line is A-1, the jacket line will be JA-1.

All lines shall have one starting point, either at an item of equipment or another line. It can not have more than one ending point; a line that branches to two nozzles on a vessel is actually two lines.

Show the last line numbers used on that P&ID in the lower right-hand corner.

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Piping Line and Item Designation

Introduction Use standard symbols to identify piping lines.

Piping Line Designation

Line designation shall be shown on the Piping and Instrument Diagram (P&ID's) and utility diagrams in a balloon, 45 mm x 5 mm, minimum. The balloon shall contain the following information:

YYY-XXXXX-ZZZ-0000

Piping material specification code

Line size

Line sequence number

Line service designation

The piping specification code comes from the piping material specification for the material in the pipe. See the heading “Piping Material Specifications” in this section for further details.

Jacketed lines shall be identified with two separate line numbers, one for the process line and one for the jacket. Service designation shall be JS for steam, JW for water, etc. The sequence number of the jacket is the same as that of the corresponding line. Example:

P-12345-4”BC01

JS-12345-8”-AC03

Insulation and tracing shall be noted below the line identification balloon.


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Piping Line and Item Designation, Continued

Example A complete piping line designation should look like the example below.

YYY-XXXXX-ZZZ-0000

T = ** C = * * Covered Line:W = Coated and wrappedF3 = Insulation class/thickness (typical)

** Specify tracing:ST = SteamEL = ElectricalD = DowthermHW = Hot waterGL = Glycol

Piping Item Designation

Piping items shall be identified on P&ID’s and utility diagrams with a symbol. Certain piping items with identifying symbols also require a designation and a sequence number in a 12 mm square. For example:

TRPXXX

Piping Line Sequence Numbering

Each line shall have a unique five-digit sequence number. The first two digits in the line sequence number shall correspond with the third and the fourth digit in the five-digit sequence number of the P&ID that shows the start of the line in the direction of flow.

The next three digits represent a serial number. On small projects, a four-digit line number can be used, so that a shorter two-digit sequence number is obtained. For example: P&ID Number Line Number B1-00120-xxxx yyy-12003-xxxxxx-xxx

Changes in Piping Characteristics

A change in size along a line does not change the line sequence number. The largest line size shall be shown on the piping line schedule. The P&ID .ALL-file shows all sizes of a line.

Lines from/to spare equipment (for example: pumps, filters) should receive a separate sequence number.


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Piping Item Numbering

Each piping item shall have a unique three-digit sequence number. The first two digits in the piping item number shall correspond with the third and fourth digit in the five-digit P&ID sequence number. The third digit is a serial number. For example: P&ID Number Piping Tag Number B1-00120-xxxx TRP-121 (for a trap)

Piping Line Symbols

Lines shall be drawn in different ways depending on service:

Type of Line Symbol

Main process line Auxiliary process, utility, or service line

Jacketed line

Piping To Be Shown

All piping shall be shown and given a line sequence number regardless of size, fluid handled, or whether it is underground or above ground. Process piping is to be shown horizontally as much as possible. Pipe lines shown shall include process prefix, line number, size, specification, tracing, and insulation code.

Utility Lines Utility lines serving a particular area or item of equipment should carry that P&ID number. It would identify a utility line with the area or equipment it serves. Since utility P&ID’s are often developed after flowsheets and other P&ID’s are created, this permits assignment of line numbers before utility P&ID’s are developed. Utility lines can be shown in one of the following methods:

• Have utility lines run vertical as much as possible • Place the utility boxes as close to the utility source or termination point on the graphic as practical

• Consider utility lines as process lines, using directional lines on the side of the sheet

Utility piping lines are seldom shown continued to the margins of the process P&ID’s. Instead, each one begins or terminates at a 14 mm × 45 mm non-directional box shown in the body of the P&ID. Inside this box the name or line number of the utility is indicated and the drawing number of the utility diagram on which this piping, instrumentation, and utility equipment is shown.

Underground Lines

Underground lines are documented in the same manner as above ground lines. Except in rare instances, underground process lines should be avoided.

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Specification Breaks

Show all specification breaks (piping, insulation, tracing, etc.) at their relative location in the process when possible.

All pipe specification breaks shall be assigned a new P&ID line number.

Specialty Piping

Use double squares to show specialty piping items (for example: strainers, traps, flame arrestors, etc.) to get a detailed equipment report.

Lines Continuing from One Sheet To Another

Process piping lines continuing from one sheet to another shall be matched at the edges of the sheets and shall be horizontal. Lines shall be numbered as close to the edges of the sheets as practical. A good practice to follow is that, with the exception of utility lines, all lines going to a P&ID with a lower sequence number leave the sheet on the left-hand side. Lines going to a P&ID with a higher sequence number leave on the right-hand side of the sheet.

This convention needs to be observed to maintain intelligent P&ID’s for use of the .ALL-file.

Traps Show steam trap piping on P&ID’s with line numbers, insulation breaks, and specification material breaks where possible. Show steam traps on P&ID’s as equipment items so the operating conditions can be correctly documented for design and operation.

Special Piping Configurations and Operating Considerations

Special piping configurations shall be indicated on P&ID’s. Examples include:

• Critical line elevations (or parts thereof) that satisfy a critical static head requirement

• Critical line lengths that minimize a critical two-phase flow pressure drop or maintain a critical residence time

• Sloped lines from one defined point to another to satisfy a critical draining requirement or a line with no pockets or low points to prevent accumulation of process material

• Liquid-seal legs to maintain a positive seal against unwanted vapor flow

• Identify only critical line lengths These, as well as all other special piping configurations, shall be shown in full detail on the P&ID’s with specific dimensions, slopes, explanations, etc.

• Identify critical operational considerations such as sloped lines, lines with no pockets, vertical for gravity drops, lines with no low points, or liquid-seal legs

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37


Pressure-Relief Devices

All pressure-relief devices (including associated piping) shall be shown at their proper locations on the P&ID’s. This includes safety valves, rupture disks, pressure-relief valves, emergency-relief valves, etc. Usually each relief device is to be numbered as a piece of equipment using double squares. Relief devices shall be numbered to match the equipment or piping that they are intended to protect. For each safety relief device, the set pressure shall be shown adjacent to the symbol.

Critical dimensions and exact piping arrangements shall be recorded for pressure-relief devices on supporting documents.

On “intelligent” P&ID’s, all relief/safety devices are extractable as specialty piping items and, therefore, are shown as double squares.

Line Weight A common practice is to show all main process lines as heavy line style. Show secondary process lines (drains, vents, startup lines) and utilities as light weight.

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Tie Points All tie points shall be shown and specification sheets generated. Tie points are locations at which piping for the new facility connects with existing facilities. Therefore, it is necessary that this is shown and uniquely identified on a document of the existing facility. This normally will be the P&ID or utility diagram.

It can consist of a reproducible piping drawing or a photograph. The exact location at which the new line is to be connected is labeled with a tie point symbol, a rectangle showing dimensions from reference points if necessary. A unique tie point number shall be shown inside. If your project uses no more than three digits for P&ID numbers, you can use the P&ID number as the first three numbers of the unique tie point number and then number the tie points sequentially on that P&ID page. Other information relating to the connection should be entered on a tie point schedule. The tie-point designation shall also be used where:

• A new instrument item is added to existing piping or equipment.

• A valve is added to an existing line or equipment item. • A new section of piping only is added to an existing line.

• An existing line is extended. When new piping, equipment, or instrumentation is being added to an existing facility and a new P&ID is being used, all new items should be drawn with solid lines. Existing piping, equipment, and instrumentation can be shown dashed (ghosted), not in clouds. Tie points should be clearly indicated.


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Demolition Drawings

Demolition drawings are required to clearly define which piping and equipment is to remain and which is to be removed. This information can be conveyed in a similar manner as tie point information is conveyed. Care should be exercised not to create too many as-built corrections as the demolition project progresses.

Operational Connections

All necessary operational connections, such as bypasses, drains, blow-PPAns, flushing, and steaming connections shall be shown. All other piping items, such as traps, bleeds, and special connections, shall be shown with size where applicable. All connections must be indicated on the P&ID independent of its application.

Pipe fittings are not normally shown; however, fittings such as special clean outs, reducers, etc., shall be shown.

Show all items for flushing, quenching, cooling, purging, venting, and draining of pumps, compressors, etc.

Drains on lines shall have a minimum nominal size of ¾ inch (20 mm). All vents and drains shall be blinded or plugged off.

Piping-Instrument Specification Break

A piping-instrument specification break is not required. The default is after the first block valve. Show exceptions. Instrument piping is not detailed, but should be compatible with process materials and/or given as a subpart of the specification for the process piping.

First Block Valve

The first block valve shall be defined by type and size by using standard P&ID symbols. The types of materials are detailed in the piping material specification.

Insulation and Tracing

Insulation and tracing shall be shown even on preliminary P&ID’s. Piping material specification breaks (piping, insulation, tracing, etc.) shall be shown by arrows at their relative location in the process when possible with the corresponding specification letters nearby (see Figure 5.J–1).

Paymeters Paymeters (accounting meters) shall be flagged or identified in some way. The letters ‘PM’ adjacent to the flow element is recommended. It is recommended that double the length of straight run pipe specified by the AGA or other bodies be used to improve accuracy.

Piping Material Specifications

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Introduction Piping material specifications define acceptable materials of construction, valves, fittings, flanges, gaskets, and accessories to contain chemicals and utilities in a safe and cost-effective manner. Piping material specifications are handled by a system that is separate from equipment specifications (SPECS). In North America they are contained in an electronic system called Piping Materials Management System (PMMS) . In Europe the system is called PPASPE. Those systems will be globalized in 1997 and become a single PPAPiping Materials Manage-ment System (GPMMS).

Piping material specifications will be required for each project. They are shown as the last four digits in the pipeline balloon on a P&ID.

Standardization

Piping material specifications are standardized for specific chemicals and utilities within The PPA Chemical Company. Each Technology Center should have standard piping material specifications developed for the fluids used frequently within their technology.

Electronic Specifications

The piping material specification systems (PMMS, PPASPE, or GPMMS) can be accessed by logging on to the Engineering VAXcluster and typing PPASPE, PMMS, or GPMMS at the DCL prompt ($). For details beyond those presented here, contact the site piping discipline representative.

Importance Piping systems contain process chemicals and utilities and must be properly designed and maintained to prevent leaks, breaks, and spills. Some piping systems will require registration, testing, and complete MOC documentation of the specifications to comply with government requirements and PPA policies.

Criteria A “standard” piping material specification is commonly called a “pipe spec.” In its simplest terms, a piping material specification is a carefully assembled and matched “parts list” of all the components required to build a complete pipe line or system. They are common, adopted specifications that represent the minimum acceptable criteria for safe and adequate material containment, based upon sound mechanical and application technology. These piping components are selected according to their ability to conform to common basic requirements or criteria, including:

• Chemical or utility service • Pressure and temperature limits • Materials and methods of construction • Corrosion allowance • Compliance with industrial piping codes • Other requirements imposed by hazards of service or local regulations

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Continued on next pagePiping Line and Item Designation, Continued

Sequence of Components

For consistency in piping material specifications, the descriptions of piping components are assembled in the following sequence:

• General and construction notes

• Pipe • Branch connections • Pipe tubing • Fittings • Flanges • Gaskets

• Bolting/fasteners • Bolt lubricants • Joint compounds • Valves • Instrument installation details

• Welding procedures • Miscellaneous and

accessories

Product-Specific Specifications

A product-specific specification is a piping material specification that has been developed for a specific chemical or service at a stated set or range of process conditions. Usually, this is related to a single, pure material rather than a mixed stream. Like all standards or “masters” it is complete, approved, and suitable for use as is, without modification. An example might be:

PPAMaster Chlorine - Dry Gas - Welded 150 psig at 250. Deg. F Material: Carbon Steel

Process-Specific Specifications

A process-specific specification is a piping material specification with a consistent material of construction, suitable for a broader range of process streams and mixed compositions within a particular process unit. It might or might not include specific chemical names in its description. Its use is governed by the piping material specification codes and the P&ID’s, which indicate for which services the specification is suitable. Within the facility or process unit, a process-specific specification also is regarded as a standard or “master” since it is complete, approved, and suitable for use without modification. An example might be:

XYZ Plant Master Process - Steel - High Pressure Dimethylamine (DMA) (Dimethylaminoethanol (DMAE) Trimethylamine (TMA) 300. psig at 100 Deg. F


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Ownership Standard or “master” piping material specifications have been owned and maintained by a number of different organizations, depending upon the range of common use, including Technology Centers, divisions, blocks, departments, plants, or temporarily by project teams. In the PPAsystem (1997), PPAor master piping material specifications will be owned by Technology Centers.

Technology Center Masters

Technology Center piping specifications incorporate the various product processing technologies, correctness, and appropriateness of numerous piping systems, based upon a broad spectrum of cumulative manufacturing experiences. Each Technology Center concentrates on areas of product expertise that are unique and specific to the business of its products. These specifications are meant to be used in all locations that employ that process technology. Furthermore, Technology Center specifications are to be used where specific chemical services interface to more than one manufacturing plant—such as styrene monomer.

Piping System Databases

Piping system databases have two parts:

• One part is a central catalogue that contains descriptions for all piping components. The main catalog is kept and maintained at DDC. All catalogue data-management activities are performed according to guidelines established by PPApiping technology specialists.

• The second part actually “builds” the piping material specification. The specification is simply a collection or association of items from the catalogue and appears as a piping material specification. There are internal rules for the sequence by which the collection is assembled to ensure that the format of a piping material specification is globally consistent.

GPMMS Database The PPAPiping Material Management System (GPMMS—a system scheduled for delivery in 1997) is a common, PPAengineering computer database consisting of piping materials data, including item numbers, descriptions, applicable size ranges, pressure/temperature code check table references, minimum and maximum allowable temperatures for the specified materials, and code check programs for use in constructing and maintaining PPATechnology Center piping material specifications.

GPMMS Ownership

The GPMMS program, or system, is owned by the PPAEngineering Application Resource Center in DDC, Houston PPA Center. The piping component catalogue is owned by PPApiping technology specialists.

MOC Changes or modifications to piping material specifications shall be in accordance with PPAMOC standards.

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Instrumentation Shown on P&ID’s

Introduction One of the functions of Piping and Instrument Diagram (P&ID's) is to define how the operating process is to be instrumented. Each instrument or analyzer required for the project is identified and shown both schematically and symbolically on the P&ID’s. The general nature of the instrument or analyzer is shown on the P&ID, and the instrument/analyzer specifications give the particular type, service, range, and perhaps the selected manufacturer. A P&ID is not a control logic diagram; control logic is shown on the specific automation and control design or its equivalent.

Instrumentation Piping

Connections from instrument and analyzers to both piping and equipment must be consistent with not only the piping material and equipment specifications, but also the instrument/analyzer specifications.

Piping items through the first valve on instrument/analyzer connections are part of the piping design and are shown on P&ID’s. All piping after the first valve is generally covered by the instrument/analyzer installation details. Although instrument/analyzer piping is normally not shown, it can be shown if necessary to provide clarity or to ensure process functionality. The applicable specification for instrument piping is the same as given for the piping or equipment to which the instrument/analyzer is attached, unless otherwise indicated. All items of instrument/anal-yzer piping can be covered in the appropriate piping material specification or as a subpart for instrumentation only. Since these items do not necessarily appear on the P&ID’s, their inclusion in the piping material specification must be verified.

The instruments and analyzers required to adequately startup, control, and shutPPAn processes might not be entirely evident from the P&ID’s. This is especially true if computer control will be used. The connections of field-mounted sensors and driven devices, such as valves to equipment and piping, must be clearly indicated. The logic for the operation of control instruments is best described in the Process Control Strategy as a part of the specific automation and control design or its equivalent.

Instruments Shown on P&ID

All instruments and analyzers required for the project, including control valves with their failure action, shall be shown on the P&ID near the process equipment being controlled.

Control Valves Control valves shall be indicated as fail close (FC), fail open (FO), or fail last (FL). A diverter valve will usually fail last. Special control valves shall be specified on specification sheets for the type preferred.

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Safety Instrumented Systems

All sensors and final elements of the Safety Instrumented Systems (SIS) shall be designated with a number common to those elements but unique to that system. If an element is used by more than one SIS it shall be designated with one SIS number per system.


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Instrumentation Shown on P&ID’s, Continued

Tag and Loop Numbers

Tag numbers shall correspond to the P&ID number and loop number. Loops can be numbered so that the valve and transmitter working together at steady-state conditions can be identified by number and/or tie line.

A site example (Terneuzen, Netherlands) for tag numbers for instruments is to have the instrument tag numbers correspond with the cubicle input numbers, which are derived from the distribution of inputs on the various input cards. A site example (Texas) for numbering loops is to start at the upper left-hand corner and number the loops as one moves to the lower right-hand corner.

A grid system is used in Michigan Engineering for assigning instrument tag numbers on P&ID’s. Each P&ID is divided with an overlay into a 10×10 grid consisting of 100 squares. The squares are numbered 00, 01, etc. up to 99. Each instrument is located within one of the squares. The last two numbers of the instrument consist of the numbers within the square where it is located on that P&ID. This makes it easy to find an instrument on any P&ID. For example:

FT-12043 A means:

• ‘FT’ is the ISA function (flow transmitter) • ‘120’ is the P&ID number • ‘43’ locates it in square 43 on P&ID number 120 • ‘A’ is used to differentiate instruments with the same tag number

An example grid is shown below.


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Grid System for Instrument Tag Numbers

FT - 12043 A

Used to differentiate between instrumentswith the same tag number.

Grid: PID overlay

P&ID number

0123456789

0 1 2 3 4 5 6 7 8 92nd number

ISA function

Symbols, Designation, and Numbering

Instrument and analyzer symbols, designation, and numbering shall be in accordance with the Design Instrument/Analyzer discipline and their work process discipline. See Section H of Chapter 5 for more information on instrument/analyzer specifications.

Instruments on P&ID’s

The table below suggests how instrument/analyzers and piping materials related to instrument/analyzers should be shown on P&ID’s.

Instrument How to Depict

Flow devices, thermowells, orifice plates, and flanges

Flow devices, other than an orifice, shall be specified for the type preferred. Thermowells, orifice plates, and orifice flanges shall be shown as separate items.

Control and interface relays

Control and interface relays shall be shown (if known). An example of a control relay that is 120 volts ac would be one that is used to start a pump or operate a solenoid for instruments controlled by a computer. The digital output from most process control computers is 24 volts dc.

Panel-mounted instruments

Local panel-mounted (field) instruments shall be identified.


Instrument How to Depict

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Control room instruments

Instruments shall be identified using appropriate symbols, such as field-mounted, panel-mounted, mounted behind a panel, mounted on the process control computer, etc.

Safety Instrumented Systems (SIS) Loops

SIS loops shall be identified.

Instrument ranges

Instrument ranges for transmitters, recorders, indicators, controllers, pressure switches, etc., shall not be shown on P&ID’s. Control valve body sizes normally should be added during design engineering.

Block valves on instruments

The first block valve on all instruments connected to process piping and equipment shall be shown.

Purge systems and tracing

Purge systems and heat tracing/insulation of instruments for winterizing or process shall be identified.

Instrument lines to or from other P&ID’s

Instrument lines going to or coming from other P&ID’s shall not be drawn to the edges of the sheets. Instead, the instrument tag symbol should be shown ghosted on the P&ID in which it connects to another instrument. Its originating P&ID number should be indicated.

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Process Control Elements Shown on P&ID’s

Introduction Process control computer addresses shall be defined when known. Process control computer aborts (shutPPAn alarms, interlocks, overrides) will be shown when known.

Control Systems from Outside Suppliers

If a control system other than a PPA process control computer (MOD™ computer) is used, control and display systems shall be defined to the extent possible during detailed engineering.

Inputs and Outputs

Input and output signals (I/O) for process control systems and computers shall be shown.

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Electrical Equipment Shown on P&ID’s

Introduction The information needed to create the electrical equipment list (schedule) and the electrical one-line diagram for a facility is determined by people who have knowledge of the process, the facility, and electrical requirements. Electrical items should be identified by unique tag items. Significant electrical loads should be listed, such as motors, process heating, and heating, ventilation, and air conditioning for buildings. Process representatives supply the required information.

Electrical engineers should discuss these requirements with the process engineers. Electrical engineers create electrical equipment schedules and one-line diagrams. Following is a brief guideline on information the electrical engineer needs to generate a electrical motor list and a one-line diagram.

Identification of Electrical Items

Electrical items (motors, heaters, tracing, etc.) shall be identified by unique tag items. The electrical items can be objects for extraction into the equipment list (based on P&ID software) and into their own list (that is, a list separate from the equipment list).

Failure Position of Motors

The failure position of electric motors shall be shown. Upon loss of control signal, but with electrical power available, motors will fail on (F.ON), off (F.OFF), or last (F.LAST).

Interlocks Hardware and hard-wired interlocks and shutPPAns shall be shown.

Switch Designation

Show hand-off-automatic/hand switch (HOA/HS) designations for all hand switches. Local convention might require other symbols to be used.

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Utility Diagrams

Introduction Utilities are systems that supplement the process system. Utility diagrams are Piping and Instrument Diagram (P&ID's) that present information on utilities. It is important that these diagrams complement information already shown on process P&ID’s.

Purpose Utility information can be included in process P&ID’s in small projects (up to about four P&ID’s). Better practice, however, is to separate all utilities on even small project P&ID’s because small projects occur frequently over the life of a facility and utility information grows. Using utility diagrams to show most of the utility information helps to simplify the process P&ID’s.

Content All known utilities should be included, such as (but not limited to) cooling water, steam, condensate, hot oil, fuel gas, heat transfer fluids, refrigeration, air, nitrogen, etc. They also include systems that might not tie directly into the process, such as fire water, wastewater collection systems, vent systems, and perhaps pressure relief, blow-PPAn systems, safety showers, and eye-wash systems.

Format Utility diagrams are B-size drawings (A1 size in Europe). Numbering is similar to that of P&ID’s. Use the same conventions as used for process piping on P&ID’s. Refer to the example utility diagram at the end of this section.

Although there is currently no standard for utility diagrams, virtually the same piping and instrument details, symbols, and conventions are used on utility diagrams as on process P&ID’s. However, there are exceptions in some locations. Check with the drafting experts at your site.

Utility Diagrams Based on Plot Plan

In some locations, utility diagrams based on a plot plan are provided. It might be desirable to provide an approved plot plan according to the process flowsheet status before creating utility diagrams based on a plot plan. The advantage is that the piping arrangement is similar to the actual layout of the facility. This can simplify pipe sizing, tie-in locations, routing, etc. For clarity, roads and buildings can be shown with lightweight lines.

Whenever practical, layout of utility diagrams should reflect the physical layout of the facility. Location of utility stations should follow the plot plan.

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Gas Service For gas services, site conventions need to determined in advance, such as:

• Are step-PPAn pressure regulators for air and nitrogen to be shown on the utility page?

• Should they be shown on each process page? • Should only the last step-PPAn regulator be shown on

the P&ID?

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P&ID Data Extraction—.ALL-File Intelligent P&ID’s

Introduction Piping and Instrument Diagram (P&ID's) are created using the Common P&ID Program. This includes not only the P&ID graphics or drawings, but also descriptive data associated with the components on the drawings.

Purpose This system creates “intelligent” P&ID’s—intelligent because they contain all the graphic and nongraphic data on the P&ID, including the connectivity relationships among the graphic figures and the documents on which they appear. The function of the system is to provide equipment, piping, and instrument/analyzer lists and schedules for all components on the P&ID. One benefit of the system is that it ensures connectivity of lines and correctness and consistency of information. As a result, the quality of the P&ID’s is enhanced.

The .ALL-file stores the information in a database. Data stored in the .ALL-file are arranged in a defined format, and programs can be written to read this file in a selective manner. Listings of virtually any information contained in the P&ID’s can be obtained this way. Contact the P&ID Resource Center in Houston for assistance or more information.

Once P&ID’s are complete, output listings are available to the user. However, some skill might be required to generate the required reports. The reports are usually generated by designers on behalf of process engineers.

Who Creates Intelligent P&ID’s?

The Common P&ID Program currently runs on an Intergraph workstation-based MicroStation CAD system. This requires an experienced and trained operator; it is unlikely that a casual user would be successful in creating usable intelligent P&ID’s. It is very important that everyone who creates and/or updates P&ID’s follow the proper procedures and protocols to preserve intelligent functionality.

Where Are the P&ID’s Stored?

Once the P&ID’s are created, they are transferred from the workstation to a VAX computer. Other programs then can extract all descriptive and relational data from the P&ID’s and store the data in a database. This file is known as the .ALL-file because of its contents (all P&ID data). The intelligent P&ID file, or .ALL-file, is located in a subdirectory on the VAX. Those with access to the program can access to the files and reports. Read and execution privileges are established by the originator of the documents.

Information available

Following is a list of reports available after completion of the P&ID’s. The word ‘Proj.’ will be replaced with the actual project name.

Report name Description Proj. ALL Proj. RA1 Process report

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Proj. RD1 Drawing data message report Proj. RE1 Equipment/nozzle data message report Proj. RE2 Equipment/nozzle list


55

P&ID Data Extraction—.ALL-File Intelligent P&ID’s, Continued

Report name Description Proj. RE3 Safety equipment report Proj. RE4 Piping non-standard material report Proj. RI1 Instrument data message report Proj. RI2 instrument/analyzer list Proj. RL2 Piping data message report Proj. RN1 Trim item list Proj. RX1 Tie point list Proj. RD2 Deleted drawing data report Proj. RE5 Deleted equipment/nozzle data report Proj. RI3 Deleted instrument data report Proj. RL3 Deleted piping data report Proj. RL4 Piping item list Proj. LOG Mother and error report

Primary and Secondary Users

Following are examples of primary and secondary users of this program, and the information they can obtain. Also available are such programs as LSCHED, TSCHED, and QSCHED, which require separate interfaces.

User Need Use

Draftspersons

Primary Draftspersons use it while debugging for accuracy, for piping line schedules and equipment lists.

Process engineers

Secondary

Process engineers use the detailed reports from the program. They use the program, for example, to work with the instrument engineer to extract data such as instrument schedules and lists.

Instrument engineer

Secondary

PIDINSTINT/ISCHED is a separate set of programs used by the instrument engineer. These programs extract instrument information from the .ALL-file database and manipulates it into a new data file. (Note that the NAME.idb interface program must be run on the NAME.ALL program before the ISCHED program can be run.) This new file is the basis for instrument/analyzer specification development. It also keeps track of instrument tag numbers that have been added or deleted.

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Piping designers

Secondary

Piping designers use piping line schedules, tie-point lists, and the piping item list.


57

P&ID Data Extraction—.ALL-File Intelligent P&ID’s, Continued

Examples of reports

Several report outputs from a typical project are listed below.

Table Number VAXmail Name Title

15.5-2 TEST.RL2 Piping line schedule

15.5-3 TEST.RE2 Equipment and nozzle list, page 1

15.5-4 TEST.RE2 Equipment and nozzle list, page 2

15.5-5 TEST.RE3 Safety equipment list

15.5-6 TEST.RI2 Instrument list and legend

15.5-7 TEST.RI2 Instrument list

15.5-8 TEST.RL4 Piping item list

15.5-9 TEST.RX1 Tie point list

15.5-10 TEST RN1 Trim item list

15.5-11 TEST.LOG Error log

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Adding Notes to P&ID’s

Introduction Various notes can be added to Piping and Instrument Diagram (P&ID's) to call attention to special instructions or unique features or show changes or revisions. Depending on their purpose, they are variously called know-how notes, “do” notes, or revision notes.

Know-How Notes Sometimes detailed information must be provided that cannot be easily handled by normal methods. Know-how notes on the P&ID’s are used for this. These notes, occasionally called job instruction notes, are shown adjacent to the item in question. Normally, numeric symbols are not used in know-how notes.

Guidelines for creating and marking know-how notes should be defined by the project team early in the project. A central registry of notes should be maintained. For example, “note A” should always say the same thing throughout a set of P&ID’s.

A short “tail” can be added to the know-how note symbol for clarity. A sequential letter is placed inside each symbol, beginning with A, and the symbol is repeated in the 75 mm space reserved along the bottom of each P&ID. Information can be provided in any convenient form—illustrations, sketches, or words.

Standard Notes Standard know-how notes appear the same way on all P&ID’s. A two-character field is used because of the number of standard notes. Standard notes are numeric and special notes are alphabetic (I and O excluded). For example, standard note 7, as it appears in the list of standard notes is note 7 on all P&ID’s.

The following standard know-how notes are in common use:

Note Description

1 Access platform required for maintenance.

2 Branch connection to be taken off top of header.

3 Flange required every ________ feet or meters.

4 Locate as close to “_________” as practical.

5 Locate ________ (tag item ) in view of ____________ (tag item).

6 Locate at highest elevation of line.

7 Valve to be locked open.

8 Valve to be locked closed.

9 Nozzle internals to be removable and accessible for maintenance.

10 Piping to be as short as practical.

11 Removable spool required.


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Adding Notes to P&ID’s, Continued

Note Description

12 Startup strainer required with removable spool.

13 Tracing for this “________” to be a separate loop by itself.

14 Allow space at the end of exchanger (shell and tube) so tubes can be accessed for cleaning or removal of bundle.

15 No line required—flange/fitting to flange/fitting makeup.

16 Mount/locate _________ (tag item) accessible from grade, platform, or ladder.

17 Locate __________ (item) close/adjacent to _________ (item).

18 No legs/pockets in this line.

19 Slope line toward _________ (item) as shown.

20 All washout valves shall be oriented PPAn.

“Do” Notes “Do” notes shall be used when a nonstandard application or installation of instruments is required.

Additions or Demolition (Revisions)

A triangle along with a cloud is used on existing P&ID’s to tag additions or demolition (revisions). The project, job number and date should be shown. The cloud circumference should cross at tie points.

Additional Information

Often it is useful to reference elements that are not piping, equipment, or instruments. Examples include gutters, dike drains, building walls, tank cars, tank trucks, elevated pump bases, dikes, etc. Where these are important to ensure process functionality, reference notes on the P&ID are appropriate.

Examples Sample graphics are shown below and on several P&ID examples.


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Adding Notes to P&ID’s, Continued

Symbols and Tags Used on P&ID’s

Symbol Description Use

Single ½-inch circle

Instrument item tag for locally mounted device

Double circle; ½ and 7/16 inch

Equipment item tag

Square or box Equipment nozzle tag

Double box Specialty piping item tag

Single diamond Instrument signal to or from a process control computer

Circle with 5-mm ID and 6-mm OD

Know-how note

Elongated oval Line balloon

Single ¼-inch circle

Status bubble

Hexagon Safety Instrumented Systems (SIS)

TP

18×16 mm box or 3/8 in. square

Tie point

T&C C

Piping and specification break for tracing and insulation

Triangle Revision mark

Irregular shape Cloud used to define area or scope of revision

proc eng p&i d

Documents