API released the APl5L standard in 1926, initially only including A25, A, and B steel grades, with minimum yield values of 172, 207, and 241MPa, respectively.
API released the APl5LX standard in 1947, which added three steel grades: X42, X46, and X52, with minimum yield values of 289, 317, and 358 MPa, respectively.
Since 1966, four steel grades have been released, namely X56, X60, X65, and X70, with minimum yield values of 386, 413, 448, and 482MPa, respectively.
In 1972, API released the U80 and U100 standards, with minimum yield values of 551 and 691Mpa, respectively. Later, API changed U80 and U100 to X80 and X100.
Roughly speaking, before 2000, the consumption of X70 in the world was around 40%, while X65 and X60 hovered around 30%. A considerable number of small diameter finished oil pipeline lines also used X52 steel grade, mostly ERW steel pipes.
There is a lot of discussion both domestically and internationally about the X80 steel grade. The steel giants who have invested heavily in the development of X80 have actively promoted X80, and even X100. Today, X80 has passed the "experimental stage", and the world-renowned West East Gas Pipeline 2 has adopted X80 steel grade for over 4843 kilometers, while the West Third Pipeline also uses X80 for about 2445 kilometers.
Update instructions for the latest version (45th edition) of 2012
The revision work started in April 2010, collecting and processing over 400 opinions. The new version of the standard was officially approved at the end of 2012 and officially launched on the ISO network on February 18, 2013.
In 2007, ISO and API jointly released the pipeline steel pipe standard ISO 3183:2007/API Spec 5L (44th edition), achieving worldwide consistency in standards. Although API terminated its cooperation with ISO in 2012 due to intellectual property and trade issues raised by the United States, it no longer participated in the drafting of ISO standards, and will not release standards that adopt ISO in the future. However, the new version of the pipeline steel pipe standard is still the result of the joint cooperation between ISO and API standards working group, and the content is consistent except for differences in API monogram and European onshore pipeline steel pipe ordering.
