... .WT: 3~30mm 3.ISO Standard,API certificate astm oil pipe 4 inch SpecificationOD 33mm - 406mm(1”~16”) with thickness of ... ,water transport, building, machinery, traffic, aviation, oil development etc. seamless pipe for low and medium pressure boiler,high prssure boiler,ship-building ... deformed5. High-precision high-quality finish high cleanliness astm oil pipe 4 inch