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 ... ) Application:petroleum,gas,chemical,power,shipbuilding,boiler,construction,,metallurgy,etc mild steel hollow pipe