mild steel hollow pipe 1) Standard:API 5L,ASTM 36.10M,A106,A53,DIN 1629,1626,BS,JIS.etc mild steel hollow pipe1) Standard ... :API 5L,ASTM 36.10M,A106,A53,DIN 1629, ... 1626,BS,JIS.etc2) Material: ASTM A106/A53,ST37,35, API 5L GR. B /X42 ... ,gas,chemical,power,shipbuilding,boiler,construction,,metallurgy,etc mild steel hollow pipe