OCTG standards for austenitic stainless steel tubes used for pressure carrying usage
Austenitic stainless steel tubes are commonly used in applications requiring high pressure or corrosion resistance; the most common application being in the manufacture of pressure-carrying equipment. When looking to use such materials, standards need to be checked to ensure safety and performance in the specific application. The internationally recognized standard for austenitic stainless steel tube used for pressure carrying applications is BS3605/1-1991.
BS3605/1-1991 provides a specification for austenitic stainless steel tubes suitable for carrying fluids with pressure. The specification provides for tests for composition, tensile strength, proof stress, Impact energy, hardness, micro-structure and stress corrosion cracking. The specification also covers requirements for inner diameter, wall thickness, length and tolerances for straight tubing and bending radius for bent tubing.
The specification provides guidelines for austenitic stainless steel composition in terms of the steel’s chemical composition. It also outlines the grain size of the steel and the types of welds permitted for pressure containing specification grade materials, namely full penetration welds and oxyacetylene coated welds.
Mn content in OCTG austenitic stainless steel is strictly limited by the specification and ranges between 12-17% dependent on the specific steel grade. Chromium is also strictly limited and ranges between 18% and 25% subsequently; this ensures good resistance to atmospheric corrosion and helps to maintain the steel’s strength and ductility.
OCTG austenitic stainless steel tubes in accordance with BS3605/1-1991 are suitable for use in applications up to and including 15 MPa. Specialized grades, such as duplex stainless steels, may provide increased pressure and fatigue resistance. Such grades should be specified when higher pressures, or exposure to vibration or shock are involved.
In addition to BS3605/1-1991, other standards such as EN10204, are often specified for specific materials. This specification provides for a Certificate of Conformity for various types of test documentation, including material and batch testing. The certification provides assurance of quality for products and can provide for traceability throughout the manufacturing and supply chain.
In conclusion, BS3605/1-1991 provides the specification of austenitic stainless steel tube for pressure carrying applications. Other standards such as EN10204, should also be consulted, as they provide additional assurance of quality through testing and certification.
