What are the Chemical Differences Between P235 and P355? P235 and P355 materials are pressure vessel steels, also known as boiler sheet. Considering the general properties, it is seen that the weldability of both materials is good. In addition, they can withstand high pressure. P235 Quality Strength Values P235 quality material is in the non-alloy steel group. As an auxiliary part when producing boilers in industrial areas, […]