what is oil and gas facilities pipeline material? PSL 1 and PSL 2
oil and gas facilities pipeline material most used is carbon steel. The API – American Petroleum Institute makes a standard named Specification for Line Pipe – API 5L. Carbon steels are widely used in the oil and gas industry despite their corrosion resistance is limited. These materials are preferred to others because of economic considerations.
The API 5L pipe steel is a low carbon steel, which is used for the fabrication of transmission pipelines. in general, there are 2 PSL ( product specification level ) ie PSL 1 and PSL 2. The development of technology for high strength pipeline steel such as X-80, X-100, and X-120 through thermo-mechanical process allowed a reduction in wall thickness and sometimes an improvement in corrosion resistance. However, the API 5L pipe is still susceptible to aqueous corrosion so inhibitor addition is a frequent corrosion control measurement
“In the preparation of this document, the technical committee maintained the concept of two basic levels of
standard technical requirements for line pipe expressed as two product specification levels (PSL 1 and
PSL 2). Level PSL 1 provides a standard quality level for line pipe. Level PSL 2 has additional mandatory
requirements for chemical composition, notch toughness and strength properties and additional NDT.
Requirements that apply to only PSL 1 or to only PSL 2 are so designated. Requirements that are not
designated to a specific PSL designation apply to both PSL 1 and PSL 2 pipe.”
in many oil and gas company, they mostly use PSL 1 e.g API 5L grade B or X42 that have higher Yield strength.
“The technical committee also recognized that the petroleum and natural gas industry often specifies
additional requirements for particular applications. In order to accommodate such needs, optional
additional requirements for special applications are available, as follows:
- PSL 2 pipe ordered with a qualified manufacturing procedure (Annex B), the requirements of which
have been enhanced to include verification detail of critical processes in the production of feedstock material, line pipe manufacture and product testing and inspection; - PSL 2 pipe ordered with resistance to ductile fracture propagation in gas pipelines (Annex G);
- PSL 2 pipe ordered for sour service (Annex H);
- Pipe ordered as “Through the Flowline” (TFL) pipe (Annex I);
- PSL 2 pipe ordered for offshore service (Annex J);
- Equations for threaded and coupled pipe and background equations for guided bend and CVN test
(Annex P).”
API 5L is the most popular standard for Oil and Gas facilities pipeline material.
after we understand oil and gas facilities pipeline material, now we can continue the next step to make a pipeline design based on ASME B31.4 for liquid hydrocarbon or ASME B31.8 for gas transportation line.
How to choose the best pipeline for oil and gas facilities? each pipe specification has specific application or specific purposes. the best pipeline specification for lower temperature is not the best pipeline for standard and high temperature. Normally for the standard operating condition, we will choose standard pipeline in PSL 1. then we will choose the best pipeline strength in specific operating pressure. A25 is the lowest strength and X70 is the highest strength and normally also has higher prices. Usually, the design engineer will use “fit for purposes” criteria.
In term of joint efficiency, it is always the best to choose seamless pipeline to get 100% efficiency. However, ASME B31.4 also give 100% joint efficiency for some welded pipeline. The discussion about joint efficiency is elaborate in design code like ASME B31.4 or ASME B31.8.