Large diameter straight seam steel pipe welding, including pre-welding, welding and welding outside the three processes. The so-called pre-welding is in the steel forming, the use of continuous high-speed gas shielded welding method of forming steel pipe welding. After the pre-welding, respectively, within the steel pipe, multi-wire submerged arc welding. In the case of high-speed gas-shielded pre-welding, there are currently two methods. One is the use of single-wire dual-power high-current high-speed gas protection pre-welding, such as the United States, Germany that is used in this way; the other is double-wire high-speed gas protection pre-welding, Japan is the use of this method. At present, more applications are monofilament high-speed gas protection pre-welding method, in a reasonable welding process conditions, can achieve not less than 7m / min high speed, and straight bead forming beautiful. Large diameter straight seam steel pipe is a product of the construction industry, steel structure is also one of the building industry, so the steel structure and straight seam steel pipe produced between the inseparable association. Now in the straight seam steel pipe plant in the steel structure accounted for most of the production, so straight seam steel pipe manufacturers for the production of steel pipe with the process and process requirements are very strict, good steel pipe to grasp the straight seam steel pipe Market dynamics, and now a large profit margins of straight seam steel pipe is gone forever, so only a large amount is king, in the increasingly serious competition in how to receive more orders bigger only grasp the quality of products at the same time And constantly grasp the market dynamics and laws to grasp the lifeline of the market.
Large diameter straight seam welded steel pipe as the first process of pre-welding, that is to ensure quality. Pre-welding quality, not only its own quality problems, but also affect the follow-up, the quality of welding. Its quality requirements, targeted mainly as follows:
1, The weld should be continuous, and the appearance of forming to avoid uneven, in order to facilitate the final quality assurance of welding;
2, To ensure the appropriate penetration depth and the amount of welding, it is necessary to ensure that welding does not crack after welding, but also within the welding does not produce burning through the phenomenon;
3, To have a higher welding speed, in order to improve production efficiency.
