... competitive price, high and stable quality. Product Name Seamless Steel Tubes for Boiler, Pressure Vessel & Heat ExchangerAmerican Standard ASTM A53,ASTM ... ,GB 6479,GB 9948,GB 18248,GB/T 18984Grade 10,20,20G,16Mn,37Mn,12CrMo,12Cr1MoV,15CrMo,35CrMo,10MoWVNb, etc.German ...