Sour Service Pipes

Interpipe has mastered the manufacturing of a new product — line pipes according to API 5L standard (Appendix H). The so-called Sour Service grades pipes are applied for transportation of oil and gas containing H2S.
Interpipe produces line pipes for operations in sour environments with outside diameter from 1,315 to 12, 75 inches (33,4 - 323,9 мм).
All transported oil and gas contains hydrogen sulfide and moisture, which often leads to metal corrosion. A part of this hydrogen sulfide is accumulated in metal, which reduces adhesion of interatomic forces in particular areas and thereby promotes formations of microcracks, leading to the subsequent rapid development of larger cracks. Interpipe SS grades are designed to prevent such Sulfide Stress Corrosion Cracking failures.

Sour Service Steel grades (SS grades)
Interpipe produces tubular goods for operation in sour environments according to the requirements of API 5L standard (Appendix Н) and NACE MR0175/ISO 15156 recommendations.
The designed chemical composition of the continuously cast billets, produced by the innovative Interpipe Steel mill for sour service pipes, demonstrates enhanced resistance to sulfide corrosion cracking with additional pressure.
Interpipe SS grades are available in minimum yield strengths ranging from 35,5 ksi to 70,3 ksi

STEEL GRADE Tensile strength, MPa (psi) Yield strength, MPa (psi)
Min. Max. Min. Max.
L245NS BNS 415 (60200) 655 (95000) 245 (35500) 450 (65300)
L245QS BQS 415 (60200) 655 (95000) 290 (42100) 495 (71800)
L290NS X42NS 435 (63100) 655 (95000) 320 (46400) 525 (76100)
L290QS X42QS 460 (66700) 760 (110200) 360 (52200) 530 (76900)
L320NS X46NS 490 (71100) 760 (110200) 390 (56600) 545 (79000)
L320QS X46QS 520 (75400) 760 (110200) 415 (60200) 565 (81900)
L360NS X52NS 535 (77600) 760 (110200) 450 (65300) 600 (87000)
L360QS X52QS 570 (82700) 760 (110200) 485 (70300) 635 (92100)
L390QS X56QS 415 (60200) 655 (95000) 245 (35500) 450 (65300)
L415QS X60QS 415 (60200) 655 (95000) 290 (42100) 495 (71800)
L450QS X65QS 435 (63100) 655 (95000) 320 (46400) 525 (76100)
L485QS X70QS 460 (66700) 760 (110200) 360 (52200) 530 (76900)
Interpipe pipes, complying with API Spec. 5L requirements for PSL 2, as well as with additional requirements of Appendix H, are marked as complying with this standard and are labeled with “S” in the class name to designate pipes for service in aggressive sour environments.

Focus on the quality
A distinctive feature of the pipes includes the requirements of corrosion resistance tests, which are conditioned by the specifics of the operation. Interpipe SS grades pipes according to API Spec. 5L (Appendix Н) are tested for resistance to hydrogen-stress cracking for 3 days, which are then tested for resistance to sulfide corrosion cracking for 30 days. Corrosion resistance tests on SS grades pipes samples have been conducted at the independent “Quality” Research and Test Center (Ukraine).
The testing laboratory has accreditation under ISO 17025:2006 and is equipped with CORTEST units, allowing the assessment of stepwise cracking resistance (NACE TM 0284-2003) and resistance to sulfide stress cracking (NACE TM 0177-2005). The Scientific and Research Center’s testing laboratory is also fully equipped with state-of-the-art units for protective coating testing.





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