What is sour service steel pipe?

Sour services steel pipe is applied for pipelines in the corrosive environment.

As we know, line pipe corrosion is an important factor affecting its safety service and service life. It will cause the leakage of oil and gas pipeline, some cases even explosion.

Pipe corrosion has a big threaten to personal safety and environment pollution, so the production of sour service pipe is important. At present, the manufacture inspection standard for acid pipe mainly according to API Spec 5L.

API 5L PSL2 X70 seamless steel pipes

1.Sour Service Pipe Definition

Sour service pipe mainly used in H2S environment. While H2S is a harmful chemicals that mostly easy to generate the corrosion.

According International regulation: When partial pressure of H2S reaches 300 pa, the line pipes used shall have the anti-acid corrosion performance.Sour service pipe includes NACE pipe.

2.How Sour Service Pipe Made

In API Spec 5L, the pipeline steel used for sour service pipe is purity fully-killed steel. (For normal line pipe steel material is grain-killed steel)

It shall be noted that, the high purity of steel can guarantee low S, P and other impurities.

In addition, the standard for the control and inspection of the inclusion shape of pipeline steel for sour service pipe is required. Because the hydrogen induced cracking caused by the inclusion is first determined in its form.

Moreover, As the pipeline steel production generally adopts controlled rolling process. Inclusion occur deformation during the rolling process. It is called linear or long strips in the rolling direction, leading to anisotropy of line pipe steel. Consequently, In order to improve the corrosion resistance of steel line pipe, the slag form should be controlled.

3.Chemical properties of sour service pipe

The content of C, P, S and carbon equivalent in the chemical composition of sour service pipe is relatively low than the normal line pipes, with a strictly control requirements. Especially for the content S, it is extremely harmful element in the corrosion environments, so for sour service pipe should control S maximum 0.002.

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