steel pipe used for construction and so on ... facilities and electricity plant facilities, stainless steel seamless pipes GBl3296-9l for boiler and heat exchanger, ... and homemade high-pressure alloy pipes of A335P11, P91, P92, etc; Primoric carbon pipes for high-pressure boiler ... GB5310-95 of 20G, 20MG, 25MG, 15MoG, 20MoG; Special pipes for fertilizer ...