Under the ASMEB311 power piping code, what material should boiler blow off fittings be made of?

According to the ASME B31.1 Power Piping Code, boiler blow off fittings must be made of steel due to the high-pressure conditions and temperatures that these components are subjected to in power piping systems. Steel possesses the necessary strength and durability to withstand the mechanical stress and thermal expansion that occur during operation. Furthermore, steel has excellent resistance to the corrosive effects of water and steam, which is crucial in maintaining the integrity of the boiler and preventing leaks or failures. Other materials like plastic, copper, and aluminum do not provide the same level of performance, strength, or durability in the contexts required for boiler blow off fittings, making steel the suitable choice for this application.