Current non-destructive testing method for a weld seam of spiral steel pipe

　　Pipeline transportation, as an efficient means of special transportation, has played an increasingly important role in oil and gas transportation and other fields. At present, domestic large-diameter transportation pipelines are mainly constructed of spiral welded steel pipes. To ensure the reliable operation of the transportation pipeline, the quality of the spiral steel pipe used must be strictly guaranteed. Therefore, researching and adopting an effective online ultrasonic automatic flaw detection system has become an inevitable choice for steel pipe production enterprises. Compared with foreign countries, the level of testing equipment in my country is relatively backward. The testing of weld seams of steel pipes is carried out by manual or semi-automatic equipment. possible defects.

　　In international bidding activities, the steel pipe production enterprises that participate in the bidding are usually required to have relatively complete testing measures. Although some companies have spent huge sums of money to import some automatic testing equipment from abroad, due to the limitations of domestic production and testing supporting conditions, other The use effect is often not ideal, resulting in many imported equipment being idle, wasting a lot of money. The current situation greatly limits the international competitiveness of domestic steel pipe manufacturers.

　　Because of its mature manufacturing process and low cost, spiral steel pipe is a kind of steel pipe mainly used in fluid-conveying pipelines. At present, continuous forming and submerged arc welding are generally used to manufacture spiral steel pipes. There are two types of forming methods: inner bearing type and outer embrace type. Since these two forming methods are generally not enough to form, the steel pipe will have a large residual stress after manufacture, which reduces the pressure-bearing capacity of the steel pipe.

　　After theoretical analysis, the formula for calculating the residual stress of the steel pipe in the case of insufficient forming is given, and the residual stress of the inner-supported spiral steel pipe is measured to verify the correctness of the formula for calculating the residual stress given in this paper. The manufacture and application have a guiding role.