What ASME standard number does urea-grade stainless steel fall under? Does it belong to super stainless steel?

I once read that urea-grade stainless steel (those with \"mod\" added to the grade designation) does not exist in ASME standards; it is actually an engineering grade material developed by certain engineering companies or material manufacturers specifically for the requirements of urea production. Later, China’s national standards also adopted this grade designation

Urea-grade stainless steels generally refer to two types: 316LMOD and 310MoLN. 316LMOD is similar to American standard S31603 and corresponds to European standard 1.4435; 310MoLN corresponds to American standard S31050 and to European standard 1.4466

This post was last edited by tjsyhx@163.com on 2016-2-25 08:48. Specific grades are not yet listed in ASME’s specifications; the term “urea-grade stainless steel” is merely a name coined in China based on its application. Such a grade does not seem to exist in ASME standards. Moreover, regulations regarding urea-grade stainless steel may vary depending on the manufacturing process: it usually refers to two grades – 316LMOD and 310MoLN. 316LMOD is similar to the American grade S31603, corresponds to the European grade 1.4435 (China’s standard grade is 022Cr17Ni14Mo2, while the European EN standard grade is X2CrNiMoN18-14-3; the American Material and Testing Association grade is UNS S31603). 310MoLN is equivalent to American standard S31050, as well as European standard 1.4466 (Chinese standard grade 00Cr25Ni22Mo2, European EN standard grade X2CrNiMoN25-22-2; commercial grade 310MoLN; American Materials and Testing Association grade UNS S31050, American Society of Mechanical Engineers grade ASME CODE CASE 2038). At present, there are no national or industry-standard grades for urea-grade stainless steels; only some enterprise-level standards established by various urea processing companies exist. Examples include China’s Wuhuan Engineering Co., Ltd.’s 14-A32S-95 “Material Requirements for X2CrNiMo25-22-2 Stainless Steel in Urea Plants” and 30-A10S-95 “Material Requirements for 316L Mod Stainless Steel in Urea Plants”, as well as Snamprogetti’s “SPC.CR.UR.510 Rev.03 – General Specifications for Austenitic Stainless Steels Used in High-Pressure Parts of Urea Plants”. The aforementioned specifications set specific requirements for the chemical composition, microstructure, and corrosion resistance of urea-grade stainless steel; however, they are not an independent material standard and should be used in conjunction with the stainless steel standards of various countries. Since urea-grade stainless steel pipes are used as fluid pipes or conduits in urea production equipment, operating in a highly corrosive medium of ammonium carbamate under high temperature and pressure, the requirements for such pipes are extremely stringent. Urea-grade stainless steel materials mainly include steel pipes, heat exchange tubes, round bars, steel plates, and welding materials. The main manufacturers of urea-grade stainless steel pipes abroad include Swedish Sandvik, Swedish Outokumpu, German SMST, and Japanese Kobe Steel, among others ； The main manufacturers of urea-grade stainless steel round bars (with a diameter of Ф325mm or less) are Swedish Sandvik and German SMST. For urea-grade stainless steel products, the aforementioned manufacturers hold a monopoly position; the prices are high and the delivery times are long. Currently, there are also many manufacturers in China capable of producing these products, gradually replacing imported ones.