Thick wall straight seam steel quality inspection according to GB/T3091-2008 "welded steel pipe for low pressure liquid delivery" provisions of the standard, steel inner and outer surfaces should be smooth, not allowed to have collapsed, cracks, delamination, lap welding, arc breaking, burn and other deeper than the wall thickness lower deviation does not exceed the allowable depth under the wall thickness deviation of the other local defects exist. Pipe should do mechanical performance test, tensile test, bending test, flattening test, guided bend test and hydraulic testing, and to meet the standard requirements. Steel should be able to withstand a certain pressure, the maximum test pressure is 5.05Mpa, hold time is not less than 5S, experiment, pipe leakage does not occur. ERW steel pipes allow ultrasonic testing, eddy current testing inspection instead of hydraulic tests. SAW pipe allows ultrasonic testing or radiography inspection instead of hydraulic tests. Q345A Q345B steel grade, is not to shock; Q345B grade is 20 degrees room temperature impact; Q345C level, is 0 degree impact; Q345D level is -20 degree impact; Q345E level is -40 degree impact. The impact of different temperatures, the impact of values ??are different. Q345A, Q345B, Q345C, Q345D, Q345E. This is a class distinction, represent mainly the impact of temperature is different and carry on! Q345B steel pipe is a steel pipe material. Q represents the yield of this material, the latter 345 refers to the yield value of this material in the 345 or so, and will increase as the thickness of the material and its yield value decreases. Straight seam steel pipe is parallel to the longitudinal weld steel pipe and steel pipe. Usually divided into metric welded steel pipe, welded thin-walled tube, transformer cooling pipes and so on. Longitudinal production process is simple, high efficiency, low cost, rapid development. Spiral Welded Longitudinal generally higher than, can narrow the billet production of large diameter pipe, you can also use the same width of the billet production of different pipe diameters. But with the same length of straight pipe joints than weld length of 30 to 100%, and lower production rate.