Effect of Bending Condition of Specimens on the Tensile Strength of X70 Grade Spiral Submerged Arc Welded Steel Pipes

X70 grade spiral submerged arc welded steel pipes of two specifications were sampled, and the tensile tests were carried out on the specimens under different bending condition. The variation tendency of stipulated total extension strength and tensile strength with bending condition of specimens was analyzed. The results show that:the bending condition of the specimens had little influence on the tensile strength and great influence on the stipulated total extension strength; the less the bending degree of the specimens was, the larger the stipulated total extension strength was; the plate specimens should be flattened before testing, and could be given a certain preload if necessary. Finally, the control requirements of bending condition in the specimen processing were put forward for manufactories.