ASTM A790 Stainless Round Tube

ASTM A790 (UNS31803, UNS32205, UNS32750, UNS32760) Duplex and Supper Duplex Seamless Stainless Steel Pipe

Product Information:

ASTM A790 Duplex and Supper Duplex Stainless Steel

Duplex and super duplex stainless steels are weldable and have moderate formability. These types of stainless steels are magnetic but to a lower extent than ferritic, martensitic and precipitation hardening grades due to the 50% austenitic content.

The ASTM A790 specification covers seamless duplex and super duplex pipes for demanding applications, with high corrosion, temperature, and pressure. Electro-fusion welded duplex and super duplex welded pipes are covered, instead, by the ASTM A928 specification.

Duplex and super duplex can be considered as ‘higher grade’ stainless steel pipes, and are available on the market in the same dimensional range of conventional A312 stainless steel pipes (size range covered by the ASME B36.19 specification).

Duplex stainless steel shows a superior corrosion resistance to grade 316 for most applications (excellent resistance to localized corrosion including intergranular, pitting and crevice corrosion; the CPT of 2205 is generally at least 35ºC). Duplex is also resistant to chloride corrosion cracking (SCC) at temperatures up to about 150ºC.

Super duplex stainless steel is a variation of the duplex steel alloy which is used in the oil & gas, chemical, power generation, mechanical and desalination industries. The higher chromium and molybdenum content of Super Duplex vs. Duplex makes it extremely resistant to uniform corrosion by organic acids like formic and acetic acid. Super Duplex also provides excellent resistance to inorganic acids, especially those containing chlorides.

Chemical Composition of ASTM A790 Duplex and Supper Duplex Stainless Steel (%)

Mechanical Properties of ASTM A790 Duplex and Supper Duplex Stainless Steel