... 9001. BOILER CERTIFICATION, API 5L )3) Many kinds of purpose (pipes for machinery, pipeline, boiler pipes)4) Very ... reasonable price5) Many kinds of shapes:round, horse hoof, oval, hexagonal, rectangular, and ... square6) Many kinds of standards: ASTM A106 GRA/B/C, ASTM A53 GRB, ... order to prevent rust. Q235 MS Seamless Square Pipe