S355NL steel is a structural steel grade. S means structural steel, 355 means min yield strength for thickness less 16mm eed in Mpa, NL mean the delivery condition. S355NL steel Specification Thickness:8-200mm Width:1500-4200mm Length:4000-18000mm. S355NL steel Techniques :Cold drawn or hot Rolled, S355NL steel Application:Whats the difference between P355NL1 and P355GH steel P355NL1 material is a pressure vessel steel grade under EN 10028-3 standard. P355NL1 plates dimensions and tolerance on dimensions should be according to EN 10028-1. P355GH steel under EN10028-2 is a kind of material for boiler and pressure vessel steel. With the yiled strength at 355 Mpa, P355GH steel plates shall be done heat treatment under Normalised.