Type and Application of High Strength API Steel Pipe

The time of issue:2014-2-21 9:14:47       Author:

In order to satisfy the ever demanding requirement of the pipelines that are used in the API steel pipe in modern industries, more and more pipeline production companies are researching and developing various kinds of high-performance steel pipes. Here lists some of them for your reference.

(1)Steel pipes with high strength and high anti-deformability
The installation environment of the high strength pipeline steel varies continuously and dramatically from plain to earthquake area or frozen soil area. Thus, in addition to the high strength, the anti-deformability is another requirement and sometimes a must under certain circumstances. But generally, the higher level of strength means the lower level of anti-deformability capacity. As a result, the application of high strength steel is limited such as X100. In light of this, many companies such as JFE developed X120 with both relatively higher strength and anti-deformability performance. KIP, Super—OLAC+HOP, SSC+DAC are some of the technologies they invented.

(2) high strength pipeline steel and acid fastness
In acid environment, the API steel pipe that used should be with high flexibility and acid fastness. X65 is this kind of pipe developed by a Japanese company. They add Nb and Mo into the steel to ensure the strength and at the same time, they refine the crystal particle to enhance the flexibility in low temperature. After the diffusion of the oxide by the TMCP technology, the flexibility is improved. The JFE Company adopted the steelmaking technology of ultra-low S and P, controlling technology of sulphide morphology by adding Ca and reducing surface flaw technology. In combination with the Super-OLAC technology and the rolling controlling technology, it successfully developed X70—the anti-acid steel used to make pipeline which is used in API steel pipe.

(3) Steel pipes with high strength and excellent HAZ tenacity
In order to satisfy the requirement of the field welding, high strength steel pipelines that are used in API steel pipe need excellent weldability and HAZ tenacity. And the best way to enhance HAZ tenacity is to refine its crystal particle. The HTUFF technology invented by a Japanese company is to diffuse the fine oxide and sulphide particles consisting of Mg and Ca into the steel in high density. By adopting this technology, the HAZ crystal particle can be refined to about 1/5 of the traditional steel with the tenacity improved more than 2 times. The JFE-EWFL technology invented by JFE Company is based on Super-OLAC with the suppression of the growth of HAZ crystal particle and thus enhancing the tenacity of HAZ.

(4) Steel pipes with thick wall
Poor conditions of the marine environments put forward even stricter request for the quality of the submerged pipeline and accordingly the steel to make the pipe. The submerged pipeline which can be used in API steel pipe demands not only the transverse strength but also the longitudinal strength. As marine petroleum exploitation extends from the coastal waters to abysmal sea, the importance of pressure resistance become even higher. Many companies did a lot of research in this area and developed successfully the high pressure-resistance steel pipes such as X65, X75 with thick wall, which are widely used in submerged pipeline installation. To reduce engineering cost and improve pipeline safety, many companies join together to take advantage of their technology strengths to invent and produce various types of high strength steel. For the sake of standardized production, they even established the production regime of high strength pipeline steel—X100 and X120.

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