Desert
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Service 03 / 14
Flow Line Laying
Laying of flow lines, oil pipelines and gas pipelines in accordance with the technical specifications of each project and standards such as API 1104 or ASME B31.3, B31.4 and B31.8, in compliance with safety standards.
- 3types of lines: flow lines, oil pipelines and gas pipelines
The service
Laying of flow lines, the pipes that carry the production of each well to the manifold or the flow station, and of the oil and gas pipelines that transport it from there.
Service features
- Execution in accordance with the technical specifications of the project and standards such as API 1104 or ASME B31.3, B31.4 and B31.8
- Compliance with safety standards
Typical stages
Planning and surveying
Terrain and route studies, environmental impact assessment and consultation with landowners and communities.
Material selection
Steel, plastic or composite pipe, with coatings such as fusion-bonded epoxy (FBE) and fittings such as valves and flanges.
Construction
Trenching and excavation (or directional drilling in difficult terrain), welding and joining of sections, backfill and compaction, and hydrostatic testing to verify tightness.
Final inspection and commissioning
Final inspection of the line and putting it into service.
Adaptable to the environment
The method changes according to the environment:
Mountain
Slopes and erosion.
Swamp
Platforms or mats.
Urban area
Coordination with authorities and traffic, and trenchless technologies such as horizontal directional drilling.
Types of lines
The type of line and the fluid it carries define the code that governs its design and construction: ASME B31.4 for liquids, ASME B31.8 for gas and ASME B31.3 for the piping inside stations and plants. Field welding follows API 1104.
Flow lines
Connect the wellhead with the production facility (manifold or flow station) and carry the fluid that the well produces.
Oil pipelines
Move crude oil or products between facilities, storage and terminals, usually over longer distances.
Gas pipelines
Carry natural gas from production or treatment to plants and consumers, with stricter requirements on pressure, location and safety.
From the right-of-way to commissioning
In more detail, the construction of a line follows this sequence:
Right-of-way preparation
Clearing, grading and marking of the strip where the line will go, with access roads for equipment.
Stringing and bending
Pipe is unloaded and distributed along the route; bends are made to follow the terrain.
Welding and weld inspection
Sections are aligned and welded under a qualified procedure; the joints are inspected, usually with non-destructive testing.
Field-joint coating
The bare area around each weld is cleaned and coated to continue the protection of the pipe.
Trenching, lowering-in and backfill
The trench is excavated, the pipe is lowered in with cranes or side-booms and then covered and compacted.
Crossings
Roads, rivers and other lines are crossed by boring or directional drilling, according to the terrain.
Hydrostatic test
The line is filled with water and pressurized above its operating pressure, holding it for a set time while pressure is recorded.
Cleaning, drying and commissioning
Pigs are run through the line to remove debris and check the internal diameter; the line is dried when required and then put into service.
Protection against corrosion
Corrosion is the main long-term threat to buried steel lines, so protection is part of the design from the start:
- External coatings (such as fusion-bonded epoxy, polyethylene or tape wraps), applied in plant, with the field joints coated on site
- Cathodic protection, with sacrificial anodes or impressed current, which complements the coating
- Inspection of the coating with a holiday detector before burial, to find defects while they are easy to repair
- Markers and warning tape to avoid damage by third parties
Testing and integrity
The hydrostatic test verifies the strength of the line and the tightness of its joints before it receives product. Once the line is in service, integrity is maintained with periodic inspection, in-line inspection with instrumented pigs and monitoring of the cathodic protection system.
Safety and environment
- Hot-work permits and gas testing before welding or cutting near facilities
- Safe excavation: trench shoring, access and exit routes, and control of nearby traffic
- Lifting plans for handling pipe with cranes and side-booms
- Environmental care: soil handling, erosion control, waste management and restoration of the right-of-way
- Coordination with landowners, communities and authorities
Reference standards
Reference standards commonly applied in the sector. They are listed for orientation and do not replace the specification of each project.
- API 1104
- Welding of pipelines and related facilities.
- ASME B31.3
- Process piping: lines inside stations and plants.
- ASME B31.4
- Pipeline transportation systems for liquid hydrocarbons and other liquids.
- ASME B31.8
- Gas transmission and distribution piping systems.
- API RP 1160
- Integrity management of pipelines; covers hydrostatic testing, direct assessment and in-line inspection with “smart pig” devices.
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