... apparatus, naval vessel etc .. medium -small size Tube & pipeVarietyAlloyTemperSize(mm)Adopted StandardDiameterWall thicknessThin-wall pipe1x,3x,5x seriesO,H14,H34,H326~1300 ... .5~5GB/T68932x6x7x seriesO,T4,T66~1300.5~5GB/T6893Thick-wall tube1x,3x,5x,8x seriesH112,O,F20~1805~40GB/T4437 ...