Long series of Pipes usually of large diameter often underground with few fittings & equipment’s mostly Pumps & Valves mainly to control the flow, that are laid with an intention to transport any fluid whether liquid or gas over long distances.

  • The design of pipeline is governed by ASME B31.4 that is code for Liquid Transportation Systems for Hydrocarbons, Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohol and ASME B31.8 that is a code for Gas Transmission and Distribution Piping Systems.
  • The constructions drawing here are termed as alignment sheet.
  • Pipeline design generally involves river crossing, highway crossing, rail line crossing etc.
  • The pipeline is Series of straight pipe welded together over a long distance.
  • The pipeline can run underground, aboveground and underwater such as a subsea pipeline.
  • Pipelines are mostly large diameter that transport bulk liquid or gas from one place to other sometimes 1000s of miles in distance.
  • In pipeline few equipment are used within the Pipeline system such as pumps, valves & instruments that support the function of the system to transport fluid safely over a long distance.




Large series & networks of Pipes within the well-defined boundaries of the plant/plot with all fittings & equipment’s like Pump, Valves, Unions & other Miscellaneous items with an intention to transfer fluid from one facility to another within those boundaries as required.

  • Piping is designed in accordance with ASME B31.3 that is Process Piping code and for power plant piping ASME B31.1 that is code for Power Piping.
  • The construction drawings here are termed as isometric drawings.
  • Piping is a Complex network of pipe & fittings within the defined boundaries of the plant.
  • Piping is mostly above ground with very few underground services.
  • Piping can be from ½” to 80” as per the plant design requirements that transfer fluid from on equipment to another within the plant boundary.
  • Variety of equipment such as a pump, valves, filter vessel, column, heat exchanger, instruments are used within the piping system that supports the function of the plant to produce finish product.

Onshore System

1 Design Codes
·         ASME B31.4 : Pipeline Transportation Systems for Liquids and Slurries

·         ASME B31.8 : Gas Transmission and Distribution Piping Systems

·         ASME B31.3 : Process Piping
2 Scope
Outside plant boundary
Cross-country (i.e. villages, fields, river, canal, railway, highway, cities, deserts, forests, hills, Ghats etc.)
Within plant boundary
(up to all nozzles/ equipment terminal points)
3 Type of pipe
Line pipes as per following code:

·         API Spec 5L: Specification for Line pipes

Assorted pipes as per following code:

·         ASTMs

·         BS

·         API 5L

4 Valves
Valves are procured as per following code:

·         API 6D: Specification for Pipeline and Piping Valves

Full Bore (FB) Ball Valves are used for smooth passage of pigs.

Valves are procured as per following code:

·         BS

·         API Standard

Full bore (FB) and Reduced bore (RB) both types of valves are used as per respective valve standards. There is no requirement for pigging.

5 Welding
Welding code:

·         API Std. 1104: Welding of Pipelines and Related Facilities

Type of welding:
Automatic / Semi-Automatic/ Manual

Welding code:

·         ASME Sec. IX: Standard for Welding and Brazing Procedures, Welders, Brazers and Welding and Brazing Operators

Type of welding:
Manual (mostly)

6 Weld joint inspection (NDT requirements)
100% by Automatic UT or RT (by using X-Ray) 5% to 100% (mostly by using gamma ray source)
7 Analyses
– Wall Thickness Analysis
– Elastic Bend Radius Analysis
– Stability Analysis for Water Bodies/ Marshy Areas
– Horizontal directional drilling design analysis
– Railroad/ Highway Crossing Analysis
– Casing Pipe Analysis for Crossings
– Seismic Analysis
– Piping wall thickness calculation [as input to Piping Material Specification (PMS)] – Piping Stress Analysis (by Caesar II). Following analyses are performed on CAESAR II·         Static Analysis·         Dynamic Analysis

·         Wind Analysis

·         Flange Leakage Analysis

·         Seismic Analysis

8 Installation
Buried (mostly) Above ground/ On rack/ slippers/ T-postal etc.
9 Special Installations
Across rivers

·         Horizontal Directional Drilling (HDD) method

·         Micro-tunneling method

Across road/ rail/ highway

·         Auger boring/ jacking boring method

·         Shallow HDD

Ghats/ Hills – Special equipment used

Special fabrication methods:

·         Modular installations

·         Finning

·         Studding

·         Jacketing

·         Spooling inside warehouse

·         U/G piping for cooling water

10 Special Equipments
·         Sectionalizing Valves (Remote operated)

·         Insulating Joints

·         Scraper Launcher/ Receiver

·         Stem Extended Valves (for buried valves)

·         Flow Tee

·         Long Radius bends (R=6D)

·         Cold field bends (R = 30D or 40D)

·         Expansion Joints

·         Motor Operator Valves (MOV)

·         Cryogenic Valves

·         Springs

11 Survey
·         Topographical Survey (all along the pipeline route)

·         Geotechnical investigation (all along the pipeline route)

·         Soil resistivity survey (all along the pipeline route)

·         Hydrological Survey for water bodies (for scour depth calculation)

·         Cadastral Survey (for RoU acquisition)

·         Wind profile from meteorology

·         Seismic study of plot

12 Corrosion Protection Coating
·         Three Layer Polyethylene (3LPE) coating

·         Three Layer Polypropylene (3LPP) coating

·         Fusion bonded epoxy (FBE) coating

·         Coal tar enamel (CTE) Coating

·         Painting
13 Cathodic Protection System
·         Impressed Current Cathodic Protection (ICCP) system

·         Sacrificial Anode (limited locations)

·         Not applicable
14 Hydrostatic testing
Gauge Plate run of 95% of ID of highest thickness of pipes

Test Pressure

·         1.25 times of Design Pressure (for liquid pipelines)

·         1.25 to 1.5 times of Design Pressure (for gas pipelines)


·         Pressure equivalent to Hoop stress of 95% of SMYS of pipe material

Hold period: 24 hours (generally)

Selection of hydrostatic test section based on elevation difference of ground profile

No gauge plate run is done. Generally card-board blasting is done to clean the piping.

Test Pressure

·         1.5 × Design Pressure × Temperature Factor


·         based on line schedule

Hold period: 2 – 6 hours

15 Preservation
Preservation of pipeline with corrosion inhibited water or by filling of inert gas (N2) Not applicable
16 Communication System
Telecom/ SCADA Not applicable
17 Pigging
Intelligent Pigging Not applicable
18 Machines/ Equipments required for installation
·         Trencher

·         Backhoe/ Excavator

·         Side Boom

·         Cold field bending machine

·         Holiday Detection Machines

·         Pneumatic/ Hydraulic Internal Clamps

Offshore System

SL. NO. Offshore PIPELINE Offshore PIPING
1 Design Codes
·         DNVGL-ST-F101 : Submarine pipeline systems

·         API RP 1111 : Design, Construction, Operation and Maintenance of Offshore Hydrocarbon Pipelines (Limit state design)

·         ASME B31.3 : Process Piping
2 Installation
Subsea (in water on seabed or buried in seabed) Deck Platform Piping (similar to plant)
3 Survey (Subsea)
·         Geophysical survey/ Bathymetric Survey by using side scan sonar, sub-bottom profiler and echo-sounder

·         Met-Ocean data collection

·         Geo-technical data of the pipeline route

Not Applicable
4 Pipes
Line pipes are utilized as per following specs:

·         API Spec 5L : Specification for Line pipes

·         DNVGL-ST-F101 : Submarine Pipeline Systems

Assorted Pipes are utilized as per following specs:

·         ASTM Standards

5 Valves
Full bore Valves for smooth passage of intelligent pigs are utilized as per spec:

·         API 6D SS : Specification on Subsea Pipeline Valves

Reduced bore valves are utilized (as there is no requirement for pigging) as per spec:

·         BS/API standards

6 Analyses
·         Wall thickness Analysis

·         On-bottom Stability

·         Span Analysis

·         Global Buckling – Lateral and Upheaval

·         Pipeline Expansion Analysis

·         Riser Design (Span , Stress & Flexibility Analysis)

·         Riser Clamp Design

·         Pipeline Crossing Design and Analysis

·         Installation Analyses such as :- Pipelay Analyses in OFFPIPE, Shore approach installation design & Analyses, Riser/ Expansion Spool installation analyses, Hoses lifting & installation analyses

·         Deck piping stress analysis using CAESAR II
7 Environmental Loads (Met-ocean Parameters)
Wave, current and external pressure and buoyancy Wind load
8 Corrosion Protection Coating
Coatings such as:–

·         Coal Tar Enamel Coating (CTE)

·         Three layer polyethylene coating (3LPE)

·         Three layer poly-propylene coating (3LPP)

·         Double layer fusion bonded epoxy coating (DLFBE)

9 Cathodic Protection System
Sacrificial Anodic Cathodic Protection (SACP) system Not Applicable
10 Welding
Welding is performed as per specification:

·         API Std. 1104 : Welding of Pipelines and Related Facilities

Mostly automatic welding on pipelay barge.

Welding is performed as per specification:

·         ASME Sec. IX : Standard for Welding and Brazing Procedures, Welders, Brazers and Welding and Brazing Operators

Manual welding at fabrication yard.

11 Weld joint inspection (NDT requirements)
100% by Automatic UT Mostly by using gamma ray source.
12 Special Equipments
·         Subsea Isolation Valve (SSIV)

·         LR Bends

·         Flow tee

·         Pipeline End Manifold (PLEM)

·         Single Point Mooring (SPM) system

·         Submarine hoses

·         Floating hoses

·         Cables and umbilical installation

·         Piggy-back pipelines

Not Applicable
13 Installation Equipment
·         Pipelay Barge

·         Derrick Barge

·         Diving support vessel

·         Dynamic Positioning (DP) barge (for deep-water)

·         Pre-fabricated deck piping
14 Installation Methods
·         S-lay Method (for shallow water installation)

·         J-Lay Method (for deep water installation)

·         Shore pull/ barge pull near Land Fall Point (LFP)

·         Along with deck structure
15 Hydrostatic testing
Gauge Plate run of 95% of ID of highest thickness of pipeline.
Test Pressure·         Minimum : 1.25 times x Design PressureHold period

·         24 hours

No gauging is done.
Test Pressure·         Maximum : As per line scheduleHold period

·         2 hours

16 NDT requirements
100% weld joints by RT or AUT Varies from 10% to 100% depending upon service.
17 Intelligent Pigging
Compliant Not applicable

[Table source: – From Web]

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