This hex nut is designed for use in pressure vessels, steam equipment, machinery, and flanged connections at temperatures ranging from -10°C to +300°C. It's manufactured to ISO 4032 standards in steel with a 5-2 strength class and metric threading. Plain steel is steel without any coating or surface treatment—it's a strong material, but on its own it offers little protection against corrosion. The product meets the requirements of AD2000-W7, TRD106, and DIN 267-13. Manufacturers listed in VdTÜV-Merkblatt 1253/4 are permitted to replace an EN 10204 3.1 certificate with manufacturer and strength class markings, a practice that's also accepted by Lloyd's Register Energy.