... the industries of oil, natural gas, ship building, chemical, environmental protection, boiler, water conservancy, electrical industry, ... oil.piling, etc.ProcessSprial Submerged-Arc Welded TypeSAWStandardAPI 5L,API 5CT,ASTM A53,ASTM A252,EN10217,EN10219,DIN,JIS ... Black Oil coating as per customers requirementTestChemical Component Analysis,Mechanical Properties(Utimate Tensile Strength,Yield Strength, ...