... quality and reasonable priceAPI Casing pipesSteel Standard: ASTM, JIS, DIN, GB, EN, BS The common materials:20#,35#,45#,20G,20MnG ... ,low-and-medium-pressurre boiler pipe GB3087-1999,Fluid pipe GB/t8163-1999,structural pipe GBT8162-1999 and hydraulic support pipe ...