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Gas Transmission Pipelines
ENGINEERING SERVICES LP
HOUSTON, TEXAS
Engineering Specification
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Gas Transmission Pipelines
1.0 SCOPE– Operation/Maintenance of Gas Transmission
Piping Systems» Design
» Fabrication
» Installation
» Inspection
» Testing
» Safety
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Intent
Provide engineering specifications for safe construction, opera-tion,
maintenance, and inspection of gas transmission piping systems.Shall meet or exceed ASME/ANSI
B31.8 and DOT 49CFR192.
Gas Transmission Pipelines
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Gas Transmission Pipelines
Exclusions– Design and fabrication of pressure vessels
covered by ASME BPV Code– Piping with metal temperatures above 450oF or
below -20oF– Design and manufacture of proprietary items of
equipment, apparatus, or instruments– Hazardous liquid pipelines (B31.4)
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Gas Transmission Pipelines
3.0 PIPING SYSTEMS DEFINITIONS– General Terms– Piping Systems– Pressure Relief– Valves
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Gas Transmission Pipelines
Piping Systems Component Definitions– Pipe and Piping Terms– Dimensional Terms– Mechanical Properties– Carbon Steel Pipe– Pipe Manufacturing Processes
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Gas Transmission Pipelines
4.0 Design, Fabrication, Operation, and Testing Terms
– LOCATION CLASS– Uprating– Pressure Terms– Temperature Terms– Stress Terms
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Gas Transmission Pipelines
5.0 MATERIALS AND EQUIPMENT– Qualifications of Materials and Equipment– Marking – Material Specifications - Steel Pipe– Equipment Specifications– Transportation of Line Pipe– Conditions for the Reuse of Line Pipe
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Gas Transmission Pipelines
6.0 WELDING– Welding Terms– Preparation for Welding
» Butt Welds
» Fillet Welds
» Seal Welds
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Gas Transmission Pipelines
Qualification of Procedures and Welders– Requirements for Piping Systems Operating at
Hoop Stresses Less Than 20% SMYS– Requirements for Piping Systems Operating at
Hoop Stresses More Than 20% SMYS– Variables Requiring Separate Qualification of
Welding Procedures and Welders– Welder Requalification Requirements– Qualification Records
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Gas Transmission Pipelines
Preheating and Stress Relieving– Preheating– Stress Relieving
» Maximum carbon or carbon equivalent» Thickness» Dissimilar materials» Fillet and groove weld limitations» Stress Relieving Temperatures» Methods of Stress Relieving» Equipment for Local Stress Relieving
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Gas Transmission Pipelines
Welding and Inspection Tests– Inspection of Welds on Piping Systems
Intended to Operate at Less Than 20% SMYS– Inspection and Tests for Quality Control of
Welds on Piping Systems Intended to Operate at 20% or more of SMYS
– Repair or removal of defective welds in piping intended to operate at 20% or more of SMYS
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Gas Transmission Pipelines
7.0 PIPING SYSTEM COMPONENTS AND FABRICATION DETAILS
– Valves and pressure reducing devices– Flanges– Standard fittings– Branch connections– Special connections fabricated by welding– Closures
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Gas Transmission Pipelines
Reinforcement of Welded Branch Connections– General requirements– Special requirements– Reinforcement of Multiple Openings– Extruded Outlets
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Gas Transmission Pipelines
Expansion and Flexibility– Amount of expansion– Flexibility requirements
Combined Stress Calculations Supports and Anchors for Above Ground
Piping Supports and Anchors for Buried Piping
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Gas Transmission Pipelines
8.0 DESIGN, INSTALLATION, AND TESTING
– Steel Pipe Design Formula» Limitations on Design Pressure, P
» Limitations on Specified Minimum Yield Strength
» Additional Requirements for Wall Thickness, t
» Design Factors, F, and Location Classes
» Fabricated Assemblies & Pipelines on Bridges
» Cover, Clearance, and Casing Requirements
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Gas Transmission Pipelines
Installation of Steel Pipelines– Construction Specifications– Inspection Provisions– Bends, Elbows, and Miters in Steel Pipelines– Pipe Surface Requirements for Pipe to Operate
at 20% or more of SMYS» Detection and repair of gouges, grooves, dents, and
arc burns
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Gas Transmission Pipelines
Miscellaneous Construction Operations– Handling, hauling,and stringing pipe joints– Installation of pipe in the ditch– Backfilling– Preventing combusible gas-air mixture in the
pipeline– Welding with gas in the pipeline– Purging of pipelines
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Gas Transmission Pipelines
Testing After Pipeline Construction– Two (2) hour strength test at 1.5 times design
pressure» Test pressures versus Location Classes
– Leak testing after construction– Safety During Tests
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Gas Transmission Pipelines
Compressor Station Equipment– Design– Electrical Facilities– Compressor Station Equipment– Safety Devices– Pressure Limiting Devices– Explosion Prevention
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Gas Transmission Pipelines
Compressor Station Piping– Gas Piping
» Specifications for gas piping
» Installation
» Testing
» Identification of valves and piping
» Piping design codes - Fuel gas, air, lubricating oil, water, steam, and hydraulic.
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Gas Transmission Pipelines
Control and Limiting of Gas Pressure– Requirements for Design of Pressure Relief and
Pressure Limiting Stations– Capacity of Pressure Relieving and Pressure
Limiting Stations and Devices» Required capacity
» Proof of adequate capacity and satisfactory performance of pressure limiting and pressure relief devices
– Uprating
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Gas Transmission Pipelines
8.5 Valves– Required spacing of gas transmission pipeline valves– Location of gas transmission pipeline valves
Vaults (Valve Boxes)– Structural design requirements– Accessibility– Vault Sealing, Venting, and Ventilation– Drainage and Waterproofing
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Gas Transmission Pipelines
9.0 OPERATING AND MAINTENANCE PROCEDURES
– Basic Requirements– Essential Features of the Operating and
Maintenance Plan– Essential Features of the Emergency Plan– Pipeline Failure Investigation– Prevention of Accidental Ignition– Blasting Effects
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Gas Transmission Pipelines
9.2 PIPELINE MAINTENANCE– Continuing Surveillance of Pipelines– Pipeline Patrolling– Leak Surveys– Permanent Repair Procedures for Injurious
Gouges, Grooves, Dents, Welding Defects, Leaks, and Nonleaking Corroded Areas
– Testing Repairs and Replacement Pipe Sections
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Gas Transmission Pipelines
PIPELINE MAINTENANCE (Continued)– Nondestructive Testing of Repairs, Gouges,
Grooves, Dents, and Welds– Pipeline Leak Records– Pipeline Markers– Abandoning of Transmission Facilities– Repositioning a Pipeline in Service
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Gas Transmission Pipelines
Miscellaneous Facilities Maintenance– Compressor Station Maintenance
» Inspection and testing of relief valves
» Repairs to compressor station piping
– Maintenance of Pressure Limiting and Pressure Regulating Stations
» Emergency valve inspection procedures
» Valve records
» Prevention of accidental operation
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Gas Transmission Pipelines
Pipeline Service Conversions– Historical Records Study– Requirements for Conversion to Gas Service– Conversion Procedure– Records of the Conversion
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Gas Transmission Pipelines
10.0 CORROSION CONTROL– External– Internal– Pipelines in High Temperature Service– Stress Corrosion and Other Phenomena– Records– Expanded corrosion control presentation is a
part of three (3) other training programs.