Profile: SP Metal is a supplier of pipe, fittings and flanges. We are an ISO 9001 and ISO 14001 certified company. 904L pipe is made from high alloy austenitic stainless steel that is known for its corrosion properties. 904L Stainless Steel Pipe is a non-stabilized low carbon high alloy austenitic stainless steel. The addition of copper to this grade gives it greatly improved resistance to strong reducing acids, particularly sulfuric acid. AISI 904L Pipe is also highly resistant to chloride attack ? both pitting / crevice corrosion and stress corrosion cracking.