steam tracing

SPECIFICATION GUIDESteam Tracing

The Heat Tracing Specialists®

ContentsSPECIFICATION GUIDE

1.0 General Provisions ............................................................................. 2-51.1 Scope1.2 Purpose1.3 References1.4 Steam Tracing Symbols and Legend1.5 Codes and Standards1.6 Specification Addenda1.7 Conflict of Documents1.8 Contractual Relationships1.9 Contract Words1.10 Definition of Plant Piping, Instrumentation and Steam Tracing Terms

2.0 Where to Use Steam Tracing ................................................................ 53.0 Selection of Steam Pressure ................................................................. 64.0 Tracing System Temperature Control Options .................................... 65.0 Tracing Methods and Design Considerations ....................................6-7

5.1 Tracing Methods5.2 Design Considerations5.3 Heat Losses Through Thermal Insulation

6.0 Tracer Selection Considerations .........................................................7-87.0 Size and Number of Tracers ................................................................8-98.0 Tracer Materials ................................................................................ 9-10

8.1 Tracer Tube Cutting and Shaping8.2 Tracer Tube Unions

9.0 Steam Supply and Condensate Trap Stations ............................... 10-119.1 Tracer Circuit Supply System9.2 Trap and Condensate Return Systems9.3 Identification9.4 Steam Trap Selection and Installation

10.0 Tracer Location and Routing ........................................................ 11-1210.1 Tracer Length

11.0 Tracers for Valves and Pumps ........................................................... 1212.0 Tracers on Vessels ............................................................................. 1213.0 Instrument Tracing ............................................................................. 1214.0 Heating Systems for Instrument Enclosures .............................. 12-1315.0 Process Piping and Supports ............................................................. 1316.0 Installation of Tracing System ..................................................... 13-15

16.1 Surface Preparation of Process Pipe and Equipment16.2 Surface Preparation of Tracers16.3 Tracer Securement to Process Lines16.4 Pressure Testing and Cleaning16.5 Selection and Application of Heat Transfer Compounds16.6 Insulation Selection/Application for Steam-Traced Piping/Equipment16.7 Selection and Application of Weather Barriers

17.0 Inspection of System .......................................................................... 15

Specification Supplements: Piping drawings, product specifications, materials estimatingand manufacturer’s installation procedures make up a part of but are not found with thisspecification.

Steam Tracing


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Steam Tracing1.0 General Provisions

1.1 Scope: This specification covers basic requirements forthe design, materials, installation, inspection and testing ofsteam tracing systems for plant piping, equipment andinstruments.

1.2 Purpose: To ensure the continuity of plant operation,certain process, service and utility pipes, equipment andinstruments will require steam tracing to keep contents offluids such as liquids, gases, vapors, suspensions andslurries from freezing, condensing, crystallizing, separatingor becoming too viscous to pump.

1.3 References: One or more of the following drawings andmanufacturers’ information will supplement this specification:

a) Piping and instrument diagrams.b) Piping orthographic drawings.c) Piping isometrics.d) Piping line index.e) Product specifications, materials estimating and

installation procedures for steam tracing materials.f) Thermal insulation specifications.

1.4 Steam Tracing Symbols and Legend: Steam tracing willbe indicated on the piping and instrument diagrams and thepiping isometrics. Lines to be heated will be shown by adashed line parallel to the pipe line and the appropriate legendafter the line number such as:

a) BT or BTS for steam tracing with a bare (convection)tracer or a tracer with a safety yellow identificationjacket (Thermon Industries, Inc., SafeTrace™ BTS).

b) IT for steam tracing which is isolated from the processpipe by a factory-applied heat retarding material fortracing temperature-sensitive materials or for energyconservation (Thermon’s SafeTrace™ SLS-IT or DLS-IT).

c) HTC for steam tracing with heat transfer compounds(Thermon’s range of heat transfer materials).

All special conditions, including heat-sensitive materials, linedor specially coated pipe or other such conditions, will beidentified on the drawings and schedules.

NOTE: Throughout this specification all references tosteam-traced piping is meant to imply all steam-tracedpiping, fittings, valves, pumps, tanks, vessels, instruments,instrument lines and any other materials or equipmentrequiring steam tracers.

All heat transfer compounds are not the same, just as allthermal insulation materials are not the same. It is impor-tant to check the technical specifications and proof ofconductance testing by following guidelines such asThermon’s “Evaluation of Steam Tracer Conductance”procedure.

1.5 Codes and Standards: All work shall comply with appli-cable federal, state and local codes and industry standards.Since issuance of standards is an ongoing process, theEngineer will identify the issuance date to which the steamtracing project is committed.

Safety precautions shall conform to the applicable require-ments of Occupational Safety and Health Standards, 29 CFR1926.

Unless otherwise indicated, the latest editions and revisions ofthe following documents are referred to in this specificationand shall be used to supplement and define the intentions andrequirements of this specification where applicable. For instal-lations outside the U.S.A., all work shall apply to correspond-ing documents or other applicable codes and standards.

• American National Standards Institute (ANSI)B31.1 Chemical Plant and Petroleum Refinery PipingZ535.1 Safety Color Code

• American Society of Mechanical Engineers (ASME)A13.1 Scheme for the Identification of Piping Systems

• American Society for Testing and Materials (ASTM)A213 Specifications for Seamless Ferritic andAustenitic Alloy-Steel Boiler, Superheater, andHeat Exchanger TubesA269 Specification for Seamless and WeldedAustenitic Stainless Steel Tubing for General ServiceB68 Specification for Seamless Copper Tube, BrightAnnealedB75 Specification for Seamless Copper TubeVOLUME 0.4.06 Thermal Insulation; EnvironmentalAcoustics (Annual Book of Standards)

• Manufacturers’ Standardization Society (MSS)MSS-SP-58 Pipe Hangers and Supports; MaterialsDesign and Manufacturers

• American Petroleum Institute (API)550 Part 1 - Process Instrumentation and ControlSection 8 - Seals, Purges and Winterizing

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SPECIFICATION GUIDE

1.6 Specification Addenda: Corrections, additions or deletionswill be accomplished by issuing addenda to this specification.Any addendum will be in the form of a letter or more formaldocuments where deemed necessary by the Engineer to:

a) Answer questions raised by bidding Contractors.b) Effect changes made by the Owner or the Engineer.c) Correct errors and discrepancies between documents.

Contractor shall submit drawings and descriptions for Owneror Engineer approval of all items which deviate from thisspecification.

Where reference is made to a manufacturer’s product,equivalent alternates may be used after receipt of writtenapproval from Owner or Engineer.

1.7 Conflict of Documents: In case of conflict between thisspecification and other contract documents, the Contractorshall, regardless of the order of precedence of documents,contact the Engineer in writing before proceeding with theaffected work. The Contractor shall only proceed after havingreceived a written answer from the Engineer that the workmay proceed.

1.8 Contractual Relationships:a) Manufacturer/Client: Owner for whom the facility is

being constructed.b) Engineer: Engineering firm undertaking the design and/

or construction of the Client’s facility.c) Purchaser: Client or the Engineer.d) Contractor: Company whose tender has been accepted

by the Purchaser.

1.9 Contract Words: These contract words should be particu-larly noted:

a) The word “shall” is used in connection with acts of theContractor or with labor, materials and equipment fur-nished by the Contractor.

b) The word “will” is used in connection with acts of theOwner or Engineer but also applies to the Contractorwhere steam tracing is provided as a “turnkey” (design,supply and install) package.

c) The word “should” is used only in connection withrecommended practices.

1.10 Definition of Plant Piping, Instrumentation and Steam

Tracing Terms:• Air Convection Tracing: Tracers attached to the pipe

without the use of heat transfer compounds. Tubing canbe bare or may have a polymer jacket. Tracer isattached to the pipe with high temperature tape andheat transfer is by means of air convection movementof heat in the annular space between the thermalinsulation and the heated pipe.

• Ambient Temperature: The temperature of the air inthe surrounding atmosphere.

• Condensate: Water that is formed in the steam tracertube when latent heat is given up by the steam to theheated pipe or equipment. Condensate is usually re-turned to the boiler for the conversion back into steam.

• Condensate Header: The principal line for collectingand routing condensate from steam users to a receiver(or to a sewer when allowed) to be pumped to the boil-er plant to reduce the reheat requirement. It may be asingle line or have several branches.

• Conduction Tracing: Tracer tube thermally bonded tothe heated pipe or equipment by heat transfer com-pound where primary heat transfer means is by con-duction directly into the metal wall of the pipe orequipment being heated.

• Dry Steam: Steam containing no moisture. It may beeither saturated or superheated.

• Heat Loss: The rate at which heat flows from a hot sur-face such as a process pipe to a cooler atmosphere,usually stated in Btu/h•ft. (W/m) of pipe. Generally, theheat loss is from the pipe through the pipe insulation tothe cooler atmosphere.

• Heat Sink: A surface or mass such as a flange or valvethat is at a lower temperature than the warm pipe.

• Heat Tracing: The application of hot liquid, vapor orsteam tracing tubes or electric heating cables or tapesto pipes, fittings, valves, pumps, tanks, instruments orinstrument lines to offset the heat loss through thermalinsulation.

• Heat Transfer Compound: A heat conductive materialwith highly efficient thermal characteristics for use onany steam or fluid tracer tube.

• Heated Pipe: Any process, service or utility pipe that isheat traced.

• Heating Media: Steam, hot water, glycol, hot oils orother heat transfer fluids that flow through tracer tubecircuits.

• Heat-Up: A steam tracing application where process


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Steam Tracingpipe or equipment requires the addition of heat to raiseits temperature from a lower to a higher level.

• High Pressure Steam: Steam at a pressure of 250-600psig (17.2-41.4 barg).

• Instruments: Devices used separately or in combina-tion to measure, analyze or monitor the various aspectsof a process.

• Instruments Piping: All piping, tubing or tubing bun-dles, valves and fittings used to connect instruments toprocess piping and to other instruments and apparatusfor measuring, analyzing or monitoring purposes.

• Isolated Tracing: Tracing for energy conservation or forsensitive piping and processes where the tracer tube isseparated from the pipe or equipment by a low conduc-tive material. Heat transfer is primarily by air convectionmovement of heat in the annular spacebetween the thermal insulation and the heated pipe.

• Low Pressure Steam: Steam at a pressure of 10-50psig (.7-3.4 barg).

• Medium Pressure Steam: Steam at a pressure of 50-250 psig (3.4-17.2 barg).

• Pockets: Bends, loops or dips in the tracer tube wherecondensate can collect.

• Process Maintenance Temperature: The temperaturelevel which must be held on plant process pipes andequipment to keep the contents from solidifying, con-densing, crystallizing, separating or becoming too vis-cous to pump. The term is often used to refer to alltraced utility, service or process pipes.

• Process Piping: Piping used to transport fluids betweenstorage tanks and process units.

• Saturated Steam: Steam of a temperature correspond-ing to its pressure.

• Service Piping: Piping used to transport water, brine,steam, air or other substances to process piping orequipment to bring about the successful completion ofthe process.

• Steam and Condensate Manifolds: Modular prefabri-cated steam supply and condensate collection unitsdesigned specifically for steam tracing circuits.

• Steam and Condensate Return Leads: Preinsulatedtubing with a weather-protective jacket used to inter-connect headers to manifolds and manifolds to tracersfor steam supply and condensate return. Referred to asleads, runs, lines and takeoffs.

• Steam Boiler: A closed vessel in which water is vapor-

ized into steam to provide mechanical power and pro-cess heat such as steam for tracing circuits.

• Steam Header: The principal steam line supplyingsteam to all users in an area including tracer circuits.Assumed to be supported on overhead pipe rack andmay have several branches.

• Steam Tracing: A tube or small pipe carrying steam,which is placed parallel and attached to the surface ofthe pipe or equipment to be heated. The tube isreferred to as the “tracer,” “tracer tube,” or simply“tracing.”

• Steam Tracing Condensate Subheader: A line whichcollects and returns condensate from one or moretracer circuits via a condensate collection manifold tothe condensate header.

• Steam Tracing Subheader: A branch from the steamheader to the steam distribution manifold for tracercircuits.

• Steam Trap: Automatic device used to hold steam in asteam tracing circuit until it has given up its latent heatand allows condensate, air and other gases to passwhile preventing the passage of steam.

• Steam-Out: A process of cleaning out the residue in apipe by passing steam through it. It is necessary to se-lect a tracer that can withstand exposure to the steam-out temperature.

• Superheated Steam: Steam having a temperaturehigher than that corresponding to its pressure.

• Temperature Controllers: Automatic devices used tocontrol steam pressure and/or flow to maintain pipetemperature for freeze protection or process tempera-ture control.

• Thermal Insulation: For steam tracing purposes, itrefers to materials used to retard the flow of heat frompipes and equipment to the surrounding atmosphere.

• Utilities Piping: Piping that transports the primary plantcommodities such as fuel gases, fuel oil, water, air,steam and condensate.

• Vessel: The term “vessel” in this specification refers toany large surface such as tanks, towers, drums, reac-tors or exchangers.

• Weather Barrier: A protective material covering theouter surface of thermal insulation to repel rain, snow,sleet, hose washdown or any other substance thatmight negatively affect the thermal insulation.

• Wet Steam: Steam containing moisture.

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• Winterization: Sometimes referred to as “freeze pro-tection” or “warming services,” winterization is thepreparation of piping and equipment for operation inwinter weather, including cold temperatures, highwinds, snow and ice.

2.0 Where to Use Steam Tracing

Steam tracing should be used when it is the practical choicefor the plant or specific units of the plant and when it ispossible for the contents of the pipes, equipment or instru-ments to freeze, condense, crystallize, separate or becometoo viscous to pump under local temperature conditions.Some guidelines are listed below.

Pipes and Equipment That Require Heating:a) In general, process lines that flow continuously during

normal plant operation need not be traced if it is practi-cal to drain the line or displace the material in the linewith a low pour-point liquid, air or gas when the plant isshut down.

b) Intermittent flow lines (and lines where it is not practicalto drain or displace the process fluid on shutdown)should be traced if the pour point of the fluid is higherthan the minimum ambient temperature that is likely tobe experienced for a period of time which will cause thefluid to set up in an insulated line without tracing.

c) Insulation alone cannot prevent freezing of lines whichhandle water or other aqueous solutions in a nonflowcondition if ambient temperature remains below freez-ing for an extended period of time. Insulation can onlyprolong the time required to freeze and can preventfreezing only if the water flow is maintained at a suffi-cient rate.

d) Pumps and their suction lines should be traced if thefluid viscosity can become high enough to greatly over-load or damage the pumps unless it is more practical toprovide for circulation during intermittent operation orfor drainage or displacement of the process fluid duringshutdowns.

e) Typical fluids that have pour points above 32°F (0°C)and require “process maintain” heat regardless of localambient temperatures include: acrylic acid, asphalt,certain concentrations of caustic soda, DMT, naphtha-lene, No. 6 fuel oil, para-xylene, phthalic anhydride,maleic anhydride, viscous oils, styrene, sulfur, tar,phenol, paraffin, urea, polypropylene, neopentyl glycol,

ammonium nitrate and many others.f) Fluids that must be “winterized” include: water, hydro-

carbons containing water and other aqueous solutions.Facilities frequently consider all process fluid streams tobe water-bearing and process gas streams to bewater-saturated.

g) Temperature-sensitive substances that must be kept“warm” but must not be overheated include: acids,amines, caustics, phenolic water, glycerin and others.

h) In addition to main process service and utility lines thatrequire heat tracing, other considerations for “winter-ization” must include: air lines, cooling towers, pumpsand associated piping, knockout pots in suction lines ofgas compressors, water “draw-off” sections of vessels,the bottom of air or gas receivers where water can col-lect, and safety and relief valves that can become re-stricted by viscous, waxy or freezing material.

Instruments and Connecting Lines That Require Heating:i) Instruments used to measure and control process gas

or fluid streams that have pour points 32°F (0°C) andbelow. These streams not only include water, they caninclude gases, light hydrocarbons and distillates that,when wet, form hydrates and solidify when subjected tofreezing temperatures. These applications can bereferred to as “freeze protection,” “winterization,” or“warming services.”

j) Instruments used to measure and control process gasor fluid streams that have pour points above 32°F(0°C). These streams may contain heavy residuals,pitch or process chemicals such as phenol that solidifyat ambient temperatures higher than 32°F (0°C). Theseinstallations must be heated above their pour point toensure free-flow.

k) Instruments and piping systems that need “custom-tailored” protection for proper operation. Processstream analyzer and emissions analyzer sample systemsfall into this category.

l) Instruments that have specific temperature limitationsimposed by the manufacturer to ensure accurate andreliable operation. Analyzers and recorders fall into thiscategory. These are delicate instruments that do nothold up well in the extreme winter/summer ambientconditions.


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Steam Tracing

3.0 Selection of Steam Pressure

The heating media should be dry saturated steam. The pres-sure of the steam is generally contingent upon the heat inputrequirements of the process piping and equipment and thepressure availability at the tracer location. The lower cost oflow pressure steam should be balanced against additionaldesign considerations. The following points should beconsidered:

a) Low pressure steam offers the maximum amount oflatent heat per pound, and the problems of flash steamfrom the condensate are reduced. However, the pres-sure at the trap must be high enough to get the con-densate into the collection system, including sufficientlift to get into elevated pipeways where necessary.Circuit lengths for trapping increase as steam pressureincreases.

b) Low pressure steam systems are more susceptible tofreezing where ambient temperatures fall below -20°F(-28.9°C). Where low pressure steam is used, steamtraps should be freeze resistant and condensate linesshould be properly protected.

c) For ambient temperatures below -20°F (-28.9°C), lowpressure steam (below 50 psig, 3.4 barg) should beused only where one tracer with heat transfer com-pound will suffice to keep process temperatures rela-tively constant during ambient temperature swings andwhere total circuit pressure losses can be kept at 10%or lower.

d) Low pressure steam may be required in some cases toprovide for lines carrying temperature-sensitive materi-als. Isolated tracers should be considered for this ser-vice.

4.0 Tracing System Temperature Control Options

Steam tracing economics can be greatly improved if tempera-ture control options are considered. The use of large safetydesign margins and the tendency to keep the tracing system“live” when there is no heat requirement should be avoidedwhere possible. Proper temperature control based on anassessment of the actual system needs should be providedwhere economically practical. Control options are:

a) Isolated tracers which provide a low conductive heatpath to reduce temperatures and conserve energy.

b) Where process temperatures above winter protectionmust be held, use self-acting control valves with sen-sors directly measuring the temperatures of the prod-uct or pipe wall.

c) For winterization, use self-acting control valves withsensors responding to the ambient air temperature.

d) Fixed-temperature discharge steam traps or balancedpressure traps which respond to condensate tempera-ture can be used to allow condensate to subcool withinthe tracer before being discharged. This enables use ofsome of the sensible heat in the condensate and reduc-es, or in some cases eliminates, the release of flashsteam.

e) To keep the process fluid temperature constant duringsummer or winter environments, to provide processheat-up after a planned or emergency shutdown with-out overshooting the maintain temperature, or for am-bient temperature-sensing control, a thermostaticallycontrolled solenoid valve can provide off-on operation.The thermostat serves only pilot duty, and off-on con-trol provides the tracer circuit with the full benefit of theheating media during start-up.

f) In many cases, control can be achieved by pressurereducing valves which vary the steam pressure.

g) Self-acting temperature controllers, fixed discharge orbalanced pressure traps and pressure reducing valvesare manufactured by Armstrong, Spirax Sarco and oth-ers. Thermostatically operated solenoid valve control-lers are provided by Thermon.

NOTE: Where controllers are used for tracing circuits,the steam traps must be of a design that continuouslydrains condensate from the circuit in order to preventwater hammer.

5.0 Tracing Methods and Design Considerations

5.1 Tracing Methods:a) Convection tracing, either “bare” or polymer jacketed

(Thermon’s SafeTrace™ BTS or Engineer-approvedequal).

b) Tracing with heat transfer compound (Thermon heattransfer compounds or Engineer-approved equal).

c) Isolated tracing (Thermon’s SafeTrace™ SLS-IT, DLS-ITor Engineer-approved equal).

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SPECIFICATION GUIDE

d) Traced preinsulated instrument tubing bundles andinstrument enclosures as provided by CellexManufacturing, Inc., or Engineer-approved equal.

e) Tracing with temperature controllers.

5.2 Design Considerations: Steam tracing is used primarily tomaintain a specified temperature range in plant piping andequipment by determining the heat loss through the specifiedthickness of insulation and replacing that heat loss with asteam tracer. A complete steam tracing system incorporatesall steam supply lines, steam tracers, heated pipes and equip-ment, insulation, steam control valves, fittings and steamtraps. The system design involves six factors: three factorsare given and three are variable. The variable factors must bebalanced to establish an appropriate design.

Given Variable(1) Nominal pipe size (4) Tracer type, size and number(2) Desired pipe temp. (5) Steam inlet temperature(3) Low ambient temp. (6) Insulation type and thickness

The following process design scenarios will be consideredbefore selecting the tracing method to be employed for eachplant line:

a) What will be the consequences of an unplannedprocess shutdown during the worst-case ambientconditions?

b) What are process control normal, upper and lower tem-perature restrictions?

c) Will the tracing system be required to heat up the pipeor equipment when the contents have become too vis-cous to pump or are in a solidified state? If so, what isthe acceptable heat-up time?

5.3 Heat Losses Through Thermal Insulation:a) To determine actual heat losses for a given set of condi-

tions, a complete insulation specification, including thethermal conductivity at several mean temperatures, willbe provided.

b) All physical and thermal properties of the specifiedinsulant will be available along with informationregarding the weather barrier mastic or jacket.

c) For composite insulation systems, conductivity will bethe average for the two insulants.

d) Soft insulants (mineral fiber, fiberglass, etc.) of the nextlargest pipe-size insulation that will accommodate thepipe and the tracer should be selected.

e) Rigid insulation (calcium silicate, expanded Perlite, cel-lular glass, etc.) may be actual process pipe size, thusrequiring board sections cut to fit the longitude joint tocompensate for the steam tracer. Preferably, the nextlargest pipe-size insulation that will accommodate thepipe and tracer should be selected. Rigid abrasive insu-lants may have an inner liner of mineral or fibrous-typeinsulation, which may also be considered in heat losscalculations.

f) Heat losses will be calculated using the actual insulationsize selected. It will be specified if the insulation is actu-al size compressed to fit the pipe and tracer or if it is“oversized” leaving an air annulus. The inner insulationsurface coefficients will vary depending upon whetheror not there is an air annulus and the size of the annularspace. The actual insulation size will also have aneffect on the outer insulation surface coefficients.

g) Actual thickness of insulation will be used since theactual thickness does not always correspond to thenominal thickness. Refer to ASTM designation C585“Standard Recommended Practice for Inner and OuterDiameters of Rigid Thermal Insulation for Nominal Sizesof Pipe and Tubing.”

h) A minimum heat loss safety factor of 10% will be used.i) Increased heat losses from miscellaneous items such as

flanges, valves, pipe shoes and supports, plus othercomponents, will be considered on critical processlines where the maintain temperature band is narrow.

j) Insulated pipe supports will be considered on criticaltemperature maintenance lines.

6.0 Tracer Selection Considerations

Most plants will require a combination of the steam tracingmethods discussed in Section 5.0 of this specification. Theselection for each heated pipe and piece of equipment willdepend upon the process sensitivity and the temperature tobe maintained along with the heat load demand, tracercapability and the results of the design scenarios.

a) Isolated tracing is selected in the following situations:(1) Where reduced thermal risk is important to aid in

compliance with applicable safety standards.(2) Where bare tracers will consume more energy

than necessary or raise the pipe temperature toohigh.


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Steam Tracing(3) Where a controlled, predictable heat transfer rate

must be maintained for energy conservation or toprevent corrosion or other unacceptable tempera-ture-related conditions.

(4) Where sensitive products such as caustics, acids,amines, resins, water and other aqueous fluids re-quire low uniform heat for freeze protection.

NOTE: The isolated tracer is a preinsulated tube with apolymer protective jacket that is superior to the traditional“spacer block” method, which suspends a tracer tube justabove the pipe on insulating blocks to maintain an air gapbetween the two. The spacer blocks are difficult to keep inposition during installation and frequently slip out from un-der the tube tracer in service because of expansion andcontraction of the tracer. Preinsulated tubing maintains thespecified distance between the pipe and is taped in placewithout involving several trades.

b) Convection tracing, either bare or Thermon’sSafeTrace™ BTS, is generally selected for thefollowing conditions:

(1) Where only one convection tracer is needed to holdthe required temperature*.

(2) Where winterization is needed for lines carryingsuch material as air, water, gases or other noncorro-sive aqueous solutions.

(3) Where low heat density and flexibility is necessaryfor high maintenance valves, pumps and other suchequipment.

(4) For process lines where ambient temperaturefluctuations or emergency shutdown and heat-up re-quirements will not necessitate more heat than theconvection tracer will supply.

* Multiple convection tracers cannot be economically justi-fied when one tracer with heat transfer compound willsuffice because of the additional steam supply connectionsand trap assemblies required. However, a convection trac-er may be doubled back where allowable pressure dropsare not exceeded.

Spiraled convection tracers on horizontal runs are notacceptable because circumferential expansion reduces theheat transfer coefficient by increasing the air gapbetween the tracer and the pipe and the increased numberof pockets requires more frequent trapping.

Spiraled convection tracers on vertical runs are not rec-ommended because circumferential expansion reducesthe heat transfer coefficient by increasing the air gapbetween the tracer and the pipe.

c) Tracers with heat transfer compound are chosen in thefollowing situations:

(1) Where more than one convection tracer is required.(2) In most cases where jacketed pipe or equipment is

ordinarily used.(3) Where fast heat-up is essential after an emergency

or a planned shutdown.(4) Where a more even temperature distribution is re-

quired.(5) Where high heat density and flexibility is required at

valves, pumps and other such equipment.d) Preinsulated instrument tubing bundles and high densi-

ty polyurethane instrument enclosures are selected forthe following situations:

(1) Where closely predicted thermal characteristics arerequired for pressure and differential pressure trans-mitters, process analyzers, emissions analyzers andother such applications.

(2) Where space is limited, pretraced and insulatedbundles can be shaped to allow layout via theshortest distance with simple supports in locationswhere field fabricated lines are not practical.

(3) Where factory-applied polymer weather protectionis preferred on critical lines.

e) Temperature controllers are selected when:(1) It is essential to prevent overheating of the product.(2) Constant viscosity is required for instrumentation.(3) Energy efficiency is a key requirement.

7.0 Size and Number of Tracers

A comprehensive review of all flow diagrams will be made todetermine the steam tracing requirements for each line.Isometric drawings identifying steam supply headers, tracersupply manifolds, tracer routing, tracer trap stations andcondensate return lines will be provided to facilitate properinstallation of the tracing system.

a) Where tracing is indicated for lines on the engineeringflow diagrams, all pumps, valves, fittings, vents, drains,instruments, instrument lines and specialty itemsassociated therewith shall also be heat traced.

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SPECIFICATION GUIDE

b) Instruments and instrument lines shall be heated inhigh density polyurethane enclosures and preinsulatedtubing bundles (Cellex Manufacturing, Inc., orEngineer-approved equal).

c) The size and number of convection tracers or tracerswith heat transfer compound required to deliver thenecessary heat energy to the traced pipe or equipmentwill be determined from published design tables(Thermon’s Steam Tracing Design Guide) or from com-puter programs developed for steam tracing design(Thermon’s CompuTrace® or other Engineer-approvedsources).

d) When heat-sensitive or corrosive fluids are to betraced, care shall be taken to prevent hot spots withinthe tracing system. Under these conditions, an isolatedtracing system utilizing a tracer with a predictable heattransfer rate (Thermon’s SafeTraceTM SLS-IT, DLS-IT orEngineer-approved equal) shall be used. A pressure re-ducing valve shall be provided for this service wherelower steam pressures are required.

8.0 Tracer Materials

The tracer in a steam tracing system must be as flexible aspossible for the ease of installation and conformance to theshape and layout of the pipes and equipment being heatedand must act as a leakproof carrier of the heating media.Whenever possible it is recommended that tubing be usedrather than pipe for tracing because the thermal expansion ofthe tubing is easier to constrain and the tracer can be heldcloser to the surface of the heated pipe or equipment toprovide a higher heat transfer rate. Pipe tracers are inflexibleand present difficulties at elbows, flanges, valves, strainers,pumps and other irregular surfaces. Since coils of tubing canbe unrolled and easily bent, tracers from tubing will require aminimum number of fittings.

The tracer shall be selected to fulfill the thermal and installa-tion requirements. These requirements are determined by theprocess pipe material, temperature of the process pipe andtracer, pressure of the heating media and the environment.The tracer shall be of metal close to the potential of theprocess pipe so as to minimize galvanic corrosion. Recom-mendations are as follows:

a) Copper tubing tracers shall be soft annealed grade 122and meet or exceed ASTM Standards B68 and B75.

Minimum wall thickness shall be as follows:3/8" O.D. x .032" wall (10 mm O.D. x 1 mm wall)1/2" O.D. x .035" wall (12 mm O.D. x 1 mm wall)3/4" O.D. x .049" wall (20 mm O.D. x 1.2 mm wall)

NOTE: 1/4" O.D. (6 mm O.D.) tracers plug up easilyand should be used only where absolutely necessaryfor heating other relatively small tubes or similar appli-cations.

b) Copper tubing shall be used if the saturated steampressure or the item being traced does not exceed400°F (204°C) and there is no corrosion or otherdeterrent for using copper.

c) Stainless steel tubing tracers shall be type 316 seam-less cold drawn and fully annealed with a maximumRockwell hardness of RB80 and meet or exceed ASTMStandard A269. Minimum wall thickness shall be as fol-lows:3/8" O.D. x .032" wall (10 mm O.D. x 1 mm wall)1/2" O.D. x .035" wall (12 mm O.D. x 1 mm wall)3/4" O.D. x .049" wall (20 mm O.D. x 1.2 mm wall)

d) Stainless steel tubing shall be used if the saturatedsteam pressure or the item being traced has a maxi-mum temperature above 400°F (204°C) and there is nocorrosion or other deterrent for using stainless steel.

e) Carbon steel tracers shall not be used for steam tracingcircuits. During shutdown periods, the combination ofair and moisture on or in the tracers causes rapid rust-ing.

f) Since the tracer tube is a primary component of thesteam tracing system, the tubing shall be thoroughlyinspected prior to use to see that it conforms to thespecifications, is of the correct diameter and thicknessand is not out of round.

8.1 Tracer Tube Cutting and Shaping: Tracer tube bends shallbe free of kinks, wrinkles or flattening. Bends shall be madewith a mechanical tubing bender. Bend radii should generallybe from four to ten times the outside diameter of the tube.The largest functional radius should be used. A tube cutter orhacksaw shall be used to cut the tracer tubes. Guide blocksshall be used with hacksaw cutting to assure a square cut.Outside diameter (O.D.) and inside diameter (I.D.) deburringshall be performed using a file for the O.D. and a deburringtool for the I.D.


10

Steam Tracing8.2 Tracer Tube Unions: Tubing unions shall be installed intracers where necessary to permit removal of equipment suchas pumps, relief valves, instruments, control valves and strain-ers. The tubing fittings shall be suitable for the pressure of thesteam which they contain. Fittings shall be compression typeas manufactured by “Swagelok” or Engineer-approved equiv-alent. The fittings shall be made of material compatible withthe tracer construction material. Tubes shall be formed to joinwith true alignment to the centerline of the fittings withoutdistortion or tension.

9.0 Steam Supply and Condensate Trap Stations

The steam supply should be taken from a source which iscontinuously available even during normal shutdown periodswhere possible. Steam should be distributed at the highestpressure and reduced to the design requirements of the tracersystem using a pressure-reducing valve.

9.1 Tracer Circuit Supply System:a) The tracing supply header shall be adequately sized to

provide the maximum tracer design load and trapped atits low point where practical and located as close aspossible to the point of use. Refer to manufacturer’sSteam Tracing Design Guide for recommended steamsupply header sizes. If three or more tracers are to besupplied from a common header, prefabricated mani-folds shall be provided.

b) Each tracer supply line from the header shall beequipped with an isolation valve. Preinsulated tubingwith factory-applied insulation and a polymer weatherprotective jacket (Thermon’s ThermoTube® or Engineer-approved equal) shall be used for steam supply andcondensate return leads and routed as follows:

(1) From off the top of the tracer supply header at thehighest point possible flowing downward to thetracer distribution manifold subheader.

(2) From the distribution manifold to the beginning ofthe tracer circuit.

(3) From the end of the tracer circuit to the steam trapcondensate manifold assembly.

(4) From the condensate manifold to the condensatereturn header.

(5) All preinsulated lines shall be routed symmetricallyand run together where possible to maintain a neatappearance. Pockets shall be avoided if possible.

c) Supply manifolds shall be strategically located along thetracing route and shall be accessible from grade, plat-forms or permanent ladders with a maximum length of16' (5 m).

d) Each manifold shall be fitted with an isolation valve andsuitable strainer, and 15% of the total number of tracerconnections shall be spares. A fraction represents onespare connection.

e) The supply manifolds shall be drained via a trap andprovided with a diffuser for safe, quiet discharge to theatmosphere when condensate is not returned to theboiler house.

9.2 Trap and Condensate Return Systems:a) Steam trap condensate manifold assemblies shall be

provided with an internal siphon tube for freeze pro-tection of traps that are shut off and a freeze protectionvalve which senses condensate temperature to drainthe manifold if the condensate cools to a given setpoint.

b) Steam trap manifold assemblies shall be placed in anaccessible location where possible to simplify mainte-nance.

c) Steam trap manufacturers (such as Armstrong andSpirax Sarco) provide steam distribution and conden-sate collection manifolds designed specifically forsteam tracing applications and are the best source ofinformation for the selection of manifolds.

9.3 Identification:a) Each tracer circuit for process lines shall be identified

by corrosion-resistant identification tags. One tag shallbe located at the steam supply valve at the manifoldand the other at the isolation valve of the steam trapassembly.

b) Steam tracer supply stations and condensate trap sta-tions will be given line numbers. An isometric pipingerection drawing will be made for each station. Thesestations will be assigned numbers which are to belocated on the plot plan and the model to indicate unitnumber, station number and whether they are supplyor trap stations.

c) The identification tags shall be fabricated from 16gauge corrosion-resistant material suitable for the envi-ronment and attached to the supply valve and steamtrap assembly valve with 16 gauge corrosion-resistantwire.

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SPECIFICATION GUIDE

d) Identification tags shall be stamped with 1/2" (12 mm)numbers and letters using the identification systemestablished for the project.

9.4 Steam Trap Selection and Installation: Effective removal ofcondensate and air is essential to achieving uniform tempera-tures and maximum heat transfer rates from steam tracingcircuits. Trap manufacturers are the best source of informationfor the selection and sizing of the steam traps and should beconsulted for sizing and proper installation techniques toprovide troublefree winter performance. Preassembled steamtrapping stations are preferred and can be supplied by thetrap manufacturers (such as Spirax Sarco and Armstrong).Several types of traps are available for tracer circuits. The typeof traps selected shall meet the design and efficiency require-ments of the tracing system.

a) The steam trap shall be installed below the tracer circuitwhere possible and at a condensate manifold locatedso as not to interfere with the operation and mainte-nance of equipment or obstruct access ways.

b) Each tracer circuit shall be trapped individually at thetracer termination point determined from the circuitdesign information. A new tracer shall be installed forcontinuing the tracing if the pipe run exceeds the maxi-mum trapping length determined in Section 10.1.

c) Isolation valves shall be installed just before and justafter the trap to make servicing easier.

d) If condensate will be discharged to an overhead returnline or against a lift, a swing check valve shall be in-stalled in the discharge line just beyond the trap at thebottom of the lift if the trap does not have an integralcheck valve or is not otherwise designed to preventbackflow. The discharge line from the trap shall feedinto the top of the return main.

e) When a trap must discharge to an overhead return line,the pressure due to the lift shall be added to the pres-sure in the overhead return line to determine the totalback pressure against which the trap must discharge.To calculate the pressure due to lift, use 0.5 psi pervertical foot of lift (11.31 kp/m). The back pressureshall not exceed the allowable limit of the selected trap.

f) If the trap does not incorporate a strainer, a strainerwith a blow-down valve shall be installed just ahead ofthe trap to keep rust, dirt and scale out of the trap. Atest tee shall be installed just downstream of the trap toallow checking of the trap performance.

10.0 Tracer Location and Routing

a) To facilitate maintenance, tracers serving the same oradjacent items shall be grouped and supplied from acommon manifold. Similarly, the condensate shall bereturned to a common return manifold.

b) The steam supply shall start (where practical) at thehighest point of the lines to be traced, and the tracersshall be arranged so that flow is generally downwardavoiding pockets as much as possible. The accumulatedvertical tracer rise (pocket height) in feet (.66 x barg forAVTR in meters) shall not exceed 15% of the steamsupply pressure.

c) Each tracer shall be continuous from the supply mani-fold to the trap with no vents, drains or dead-end ex-tensions at intermediate points. In general, branchconnections shall be avoided. If branches are required,each branch used shall have its own trap.

d) For ease of installation and serviceability, all tracersshall be installed parallel to and against the heated pipeor equipment and shall be placed on the most accessi-ble surface location in regard to supports, ease of in-stallation, connection and thermal insulation. Multipletracers shall be equally spaced around the circumfer-ence of the pipe.

e) Expansion of bare (convection) tracer tubes shall beabsorbed at elbows and flanges where possible. Forlong straight runs, a 12" (.305 m) diameter horizontalloop shall be provided at 60' to 100' (18-30 m) inter-vals, preferably midway between fittings. Tracer loopsprovided specifically for expansion should not containunions. Tracers with heat transfer compound do notrequire expansion loops.

f) Tracer loops around flanges shall be horizontal so as todrain on shutdown, and unions shall be provided sothat tracers can be disconnected at valves, pumps,tanks or other flange-connected equipment.

g) Tracing shall be included on dead legs and similar heatsinks along the traced line.

h) Each tracer shall be served by a single trap at the endof the tracer circuit.

i) Slots shall be provided in the thermal insulation toaccommodate expansion of the tracer where it joinsand leaves the traced line. Details will be provided inthe insulation specifications.

j) Extra tracer lengths are not generally required at pipehangers, piping tees and ells.


12

Steam Tracingk) Design shall include extra tracer length for valves or

large pieces of equipment. The Engineer will indicate oncritical service if pipe supports or flanges require addi-tional tracer length. Insulated pipe supports will be con-sidered on critical temperature maintenance situations.

l) All tracers shall be arranged such that maintenance andremoval of valves, instruments and other such equip-ment is not adversely affected.

10.1 Tracer Length:a) Refer to manufacturer’s Steam Tracing Design Guide to

obtain recommended circuit lengths for trapping. Long-er tracer runs may be possible based on the actual cal-culated heat loss for a given pipe under equilibriumconditions and the allowable circuit pressure drop. Acomputer-generated design from Thermon’sCompuTrace® program or other Engineer-approvedprograms may be used for circuit length optimization.

b) Tracer circuit lengths will be calculated on a maximumallowable pressure drop of 30% of the steam supplypressure but will generally be designed for a 10% pres-sure drop. Maximum tracer length is measured fromthe point where the tracer first contacts the line to beheated to the point where it connects to the trap or thepreinsulated tubing routed to the trap.

c) Pressure losses for preinsulated tubing runs from thesteam manifold to the tracer circuit, from the tracer tothe condensate manifold, and from the manifold to thecondensate return header will be calculated separatelyif the length of these runs exceeds 100' (30 m) total.

11.0 Tracers for Valves and Pumps

a) Tracing for valves and pumps shall be tubing in theform of hairpin loops so that the tracer makes the leastamount of complete circles. The number of feet of trac-er to surface area of valve or pump shall be sufficient tobalance the feet of tracer on the straight pipe surfacearea.

b) Unless otherwise specified, hairpin tubing loops shallbe attached to the valve or pump surface with 1/2" x.020" (12 mm x .5 mm) stainless steel bands, high tem-perature fiberglass tape or No. 16 gauge stainless steelwire (see supplemental tracer installation drawings).

12.0 Tracers on Vessels

a) Unless otherwise specified, external tracing for vessels

shall be stainless steel panels prefabricated to the re-quired radius (Thermon’s HeetSheet® or Engineer-approved equal).

b) Heating panels shall have a layer of factory-appliednonhardening heat transfer compound between thevessel surface and the back of the heating panel.

c) Small equipment with an outside radius of curvatureless than 7" (178 mm) and vessel bottoms with com-pound curved surfaces may be traced with tubing in theform of hairpin loops in lieu of heating panels.

d) Unless otherwise specified, hairpin circuits shall be em-bedded in heat transfer compound (see supplementaldrawings for installation details).

e) Vessels shall be insulated with double-locking, continu-ous-standing seam insulation panels (Thermon’sThermaSeamTM or Engineer-approved equal).

13.0 Instrument Tracing

a) Tracing for instruments and instrument impulse linesshall conform with information provided in the supple-mental drawings. Preinsulated tubing shall be Cellex’sTubeTrace® or Engineer-approved equal.

b) Tracing shall be designed such that instruments can beremoved for maintenance without interruption or re-moving the tracing.

c) Tracing shall be applied only to the process wettedparts of instruments, not to electronic or pneumaticparts.

d) Tracer sizes shall be as follows:(1) 1/2" (12 mm) O.D. tubing for gauge glass and

external displacer level instruments.(2) 1/4" (6 mm), 3/8" (10 mm) and 1/2" (12 mm)

O.D. tubing for meter leads.

14.0 Heating Systems for Instrument Enclosures

a) Pressure gauge enclosures shall be heated with theheat from the process line by installing heat conserva-tion insulation up to the enclosure or by continuing thetracer at the gauge connection.

b) Differential pressure transmitters with partial enclosuresshall be heated by a steam heater block installed underthe instrument. Heater shall have its own flexible ther-mal insulation cover and be installed where it will notinterfere with removal of the transmitter.

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SPECIFICATION GUIDE

c) Transmitters, controllers, recorders, etc., with completepolyurethane enclosures shall be heated with a sepa-rate finned steam heater connected by tube fittings tothe steam tracer. Heaters and controllers shall be byCellex Manufacturing Company or Engineer-approvedequal.

NOTE: Where possible, preinsulated tubing bundlesshall be used in lieu of field traced and insulated instru-ment lead lines.

15.0 Process Piping and Supports

a) The Pipe Support Group will see that all process pipingis properly secured by supports, guides, anchors orhangers in keeping with the piping specifications. Tothe greatest extent possible, any appendages shall bearranged such that tracers and thermal insulation canbe installed in accordance with specified practices.

b) The installation and support of preinsulated instrumenttubing bundles and preinsulated steam supply and con-densate return lines is given in the supplemental draw-ings. Generally, however, routing and support is to bedetermined in the field. Lines shall be run together asmuch as possible for common support. Preinsulatedtubing shall be spaced and located with these consider-ations:

(1) Ability to place a durable support at some desiredlocation.

(2) Keep sag in the line within limits that will permitdrainage.

(3) Avoid bends that exceed the minimum bend radiusas recommended by the manufacturer.

(4) Allow for heat dissipation by keeping a 1/2"(12 mm) space (minimum) between the preinsulatedlines.

16.0 Installation of Tracing System

After the process pipe has been installed with proper supportsand hangers to allow for correct application of tracers andinsulation, the following are major steps for installation of thetracer system:

a) Surface preparation of process piping.b) Surface preparation of tracer.c) Installation of tracer and its securement.

d) Pressure testing of tracer.e) Application of heat transfer compound

(where required).f) Curing of heat transfer compound (if required).g) Inspection of tracer system (see 17.0).h) Application of thermal insulation.i) Application of weather barrier.j) Inspection of insulation (see 17.0).

16.1 Surface Preparation of Process Pipe and Equipment: Incases where the pipe is located in a corrosive atmosphere orwhere corrosive leaks or spillage may possibly attack thepiping, the coatings and painting engineer will specify corro-sion protection coatings that are compatible with the steamtracing system requirements. The following general guidelinesshould be considered:

a) Before installation of steam tracers, all tracer tubes andpipes or equipment to be traced shall be reasonablyclean. Dirt, rust and scale can be removed with a wirebrush. Oil and grease films may be removed with a ragand suitable solvent. Where required, mill varnish orother coatings may be removed with a suitable stripper.Preparation for the application of heat transfer com-pound is covered in the supplemental drawings and in-stallation details.

b) Carbon steel pipe and equipment operating above175°F (80°C) need not be coated or painted to preventrusting.

c) Carbon steel pipe and equipment operating below175°F (80°C) may require a surface preparation andcoating specified by the coatings and painting engineer.

d) Stainless steel pipe and equipment in ordinary atmos-pheres need only to be cleaned as specified in a)above. However, where it may be subjected to chlorideor fluoride ions, the corrosion engineer should deter-mine the necessity to paint (coat) the surface.

e) Copper or brass pipe or equipment in ordinary atmos-pheres need only to be cleaned as specified in a)above.

f) Aluminum pipe or equipment may need to be painted ifit is in a highly caustic or salt atmosphere. Surfacepreparation for the application of heat transfer com-pound is specified in the supplemental drawings and in-stallation details.

16.2 Surface Preparation of Tracers: All tracers shall be free ofdirt, grease, oil, loose scale or any other nonspecified material


14

Steam Tracingbefore installation on piping and equipment and prior toapplication of heat transfer compound when applicable.

16.3 Tracer Securement to Process Lines: It is important toprevent stress in the tracer tubing by providing for expansionwhere required and by properly securing the tracer to theprocess pipe. Tracers are fastened to plant piping and equip-ment with wire, bands and high temperature tapes. Sometracers are covered with galvanized or stainless steel channelsbefore final attachment. Each method of tracing in this specifi-cation (bare convection tracing, tracing with heat transfercompound and isolated tracers) shall be installed in accor-dance with the installation instructions provided in thesupplemental drawings. Care shall be taken to use fasteningmaterials that are galvanically compatible with the pipe andtracer materials. High temperature tapes shall be virtually freeof chlorides or halides if used to secure stainless steel pipe ortubing.

16.4 Pressure Testing and Cleaning:a) Steam supply headers and pipe or tubing runs to

tracers shall be blown clean with steam or air beforeconnection to trap assemblies.

b) After all tracer connections to the supply header andtrap have been completed, the circuit shall be tested forleaks by subjecting it to a steam pressure equal to orgreater than that which is to be used in the system orby suitable hydrostatic tests. All leaks shall be repairedand the system retested prior to the installation of heatconducting compound (when used) and insulation.

c) Performance of traps, gauges, pressure relief valves,and pressure and/or temperature controlling devicesshall be periodically checked at prescribed intervalsduring start-up and the first 48 hours of normal opera-tion.

16.5 Selection and Application of Heat Transfer Compounds:Various formulations of heat transfer compounds are availableto cover a wide range of tracing applications. The selection ofthe proper formulation will involve consideration of all thefollowing:

a) Minimum and maximum temperatures to which heattransfer compounds will be exposed under both normaland abnormal operating conditions.

b) Ambient conditions under which installation of heattransfer compounds must occur.

c) Piping and equipment size and configuration.d) Total installed cost for the heat transfer compounds.e) Feasibility of carrying out start-up curing procedures

(where required).f) Solubility resistance of the heat transfer compounds.

To make the proper selection, basic characteristics of thevarious formulations are detailed in the supplemental drawingsand installation details.

Heat transfer compounds shall be supplied by an ISO 9001certified manufacturer such as Thermon Industries, Inc., orEngineer-approved equal.

16.6 Insulation Selection and Application for Steam-TracedPiping and Equipment:

a) The insulation material to be used on steam-traced pip-ing and equipment shall be selected with care. Impor-tant aspects to be considered are:

(1) Thermal insulating characteristics.(2) Mechanical strength characteristics.(3) Chemical stability characteristics under both normal

and abnormal conditions.(4) Moisture absorption characteristics.(5) Personnel health and safety aspects.(6) Installed cost.

b) The following thermal insulation materials and the cor-responding ASTM Standard are commonly used forsteam-traced piping:

Type ASTM StandardCalcium Silicate ............................ C533Cellular Glass ................................ C552Fiberglass and Mineral Wool ........ C547, C553, C592Expanded Perlite ........................... C610

c) The insulation materials listed in b) above all haveupper temperature limits beyond the level required forsteam tracing systems. For process temperatures below212°F (100°C), insulation materials with a low moisturepermeability should be considered for use. The manu-facturer’s maximum and minimum temperature limitsshall be adhered to when specifying the insulation ma-terial.

d) Pipe insulation is dimensionally described by the stan-dard pipe size that it is designed to fit and by its nomi-nal insulation thickness. For example, a 4" x 1-1/2"

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SPECIFICATION GUIDE

(100 mm x 38 mm) pipe insulation is designed to fitsnugly around the actual 4.5" (114.3 mm) outsidediameter of the pipe and will be nominally 1-1/2"(38 mm) in thickness. In some cases, the actual thick-ness may be as much as 25% greater than the nominalvalues.

e) Manufacturer specifications shall be consulted foractual dimensional data. ASTM C585, “Standard Rec-ommended Practice for Inner and Outer Diameters ofRigid Thermal Insulation for Nominal Sizes of Pipe andTubing,” is an additional data source.

f) Dimensions for prefabricated fittings can be found un-der ASTM C450, “Prefabrication and Field Fabricationof Thermal Insulation Fitting Covers for NPS Piping.”

g) Insulation covers for valves, flanges, pipe supports andother line equipment shall be fabricated from block orcurved segments of the same material and thicknessused for the adjacent straight piping. Cracks and jointsshall be appropriately filled and sealed to assure uni-form heat loss throughout the length of the line.

h) Thermal insulation sizes to fit over steam tracers areprovided in the supplemental drawings and installationinformation.

16.7 Selection and Application of Weather Barriers: Theproper operation of any tracing system depends upon theinsulation being dry. Properly designed and installed weatherbarriers minimize the migration of water into the insulation andare therefore a very necessary part of an effective insulationsystem. The two types of weather barriers most commonlyused are jacketing and mastic.

Manufacturers are the best source of information for weatherbarriers, mastics and other insulation accessories. ASTMStandards provide another source of data. Jacketing materialssuch as aluminum, ASJ, FPR and stainless steel are covered inASTM C921 along with banding and other accessories. Thevarious mastic materials used for weatherproofing may belocated in ASTM C647.

Double-locking, continuous-standing seam insulation panels(Thermon’s ThermaSeam™ or Engineer-approved equal) shallbe used for tank insulation and weather protection require-ments.

17.0 Inspection of System

The Inspectors shall ensure that all phases of the installationare in accordance with the materials and application specifica-tions. The Inspector shall make certain that:

a) All materials used are as specified and in goodcondition.

b) All materials are stored in accordance withrecommendations.

c) Surface preparations are as specified.d) Tracer systems are installed in accordance with the

design.e) All tracing supply headers, preinsulated supply and

condensate tubing runs, tracer tubes and manifolds aresteam cleaned prior to connection to trap assemblies.

f) All tracer circuits and process pipe runs are pressuretested after all connections are completed.

g) Heat transfer compounds are installed in accordancewith these specifications.

h) Heat transfer compounds are properly cured.i) Water soluble heat transfer compounds are protected

from rain and other moisture prior to installing thethermal insulation and weather barrier.

j) High temperature insulation is of proper thickness andinstalled in accordance with specifications.

k) Insulation was dry when installed and protected fromrain and moisture until weather barrier was installed.

l) All insulation on vessels is properly supported.m) Suitable insulation expansion joints are installed.n) Weather protection is of type specified, installed in ac-

cordance with specifications and recommendations anddry thickness of mastic is of specified dimension.

o) All weather barriers are watertight and projections andterminations are properly sealed.


16

Steam TracingNOTES:

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THERMON . . . The Heat Tracing Specialists®

100 Thermon Dr. • PO Box 609 • San Marcos, TX 78667-0609Phone: (512) 396-5801 • Facsimile: (512) 754-2420 • 1-800-820-HEATwww.thermon.com