Materials Selection
Selection of line pipe material and specification of welding procedures is extremely important for successful arctic pipeline projects. For arctic service based on limit state design, the behavior of the line pipe under bending must be fully understood. An Engineering Critical Assessment (ECA) is usually required to establish an allowable strain level, and to specify allowable flaw size that can be accepted during welding of the line pipe. Allowable flaw sizes are increased by specifying a combination of pipe with a low SMYS (X-52, for example), which typically provides good ductility, a special pipe chemistry, and a slight grade over-match of the weld electrode material.
The services INTECSEA can offer regarding materials selection are as follows:
- Materials selection for flowlines, steel catenary risers (SCRs) and subsea equipment (wellheads jumpers, and manifolds) specifying material chemistry, mechanical property requirements, dimensional tolerances and inspection requirements.
- Specifying requirements for forgings (including J-lay collars and flexjoints), induction bends, anodes (tapered, use of doubler plates, PU tapers), bolts, nuts and gaskets.
- Specification preparation for all material components including line pipe and subsea equipment.
- INTECSEA has gained extensive metallurgical experience using carbon steel, high strength low alloy steels, austenitic, martensitic (13 Cr) and duplex stainless steels, titanium alloys, clad and lined pipe and other corrosion resistant alloys. This experience is valuable when assessing material requirements for sour service.
- Strong knowledge of line pipe mill capabilities worldwide and the various manufacturing processes (i.e. DSAW, seamless, HFIW, Clad, and pipe-in-pipe systems) is key to help projects meet aggressive schedules.
- Failure analysis, metallography (including optical, scanning and transmission electronmicroscopy).
- Addressing low or high temperature material requirements and relevant testing.
- Experience with identifying and managing the following types of failure mechanisms: fatigue, corrosion fatigue, corrosion failures, stress corrosion cracking, ductile and brittle fractures, hydrogen embrittlement, creep and stress rupture.
- Specialist materials testing and specifying acceptance criteria for strain aging, fatigue, weldability, collapse and sour service (HISC, SOHIC, HE, SSCC and the full ring test).
- Setting up and managing testing programs for fatigue, sour service, large and small scale mechanical testing in the laboratory and field.
- Procurement support services to ensure that the selected manufacturers/suppliers have adequate technical integrity, that the various procedures meet all project requirements and that all the fabrication activities are carried out in a satisfactory manner, meeting the requirements stated in the applicable project documents.
- Providing surveillance for the following activities: Attending pre-production meetings, witnessing manufacturing procedure qualification tests (MPQTs), monitoring steel production, monitoring pipe manufacturing processes and mechanical testing, monitoring during line pipe and field joint coating and anode manufacture, etc.
- Review manufacturing procedure specifications (MPS), quality plans, inspection and test plans (ITP), welding procedures (WPS/WPQ’s), forging and heat treatment procedures, NDE procedures, coating procedures, material traceability systems, production plans and schedules, QA/QC procedures and other various documentation used as the basis for manufacturing of various components.
- Procurement and fabrication support for all subsea components, including line pipe, forgings, anodes, valves, wellheads, jumpers, manifolds etc.
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