Three links

Carbon steel, cast steel, alloy steel, stainless steel, copper, aluminum alloy, plastic, argon, pvc, etc.

Divided by production method

Topping, pressing, forging, casting, etc.

Divided by manufacturing standards

National standard, electric standard, chemical standard, water standard, American standard, German standard, Japanese standard, Russian standard, etc., as follows: GB/T12459-2017, ASME B16.9, SH3408, SH3409-96, SH3410-96, HG/ T21635, DL/T 695, SY/T 0510, DIN 2615.