Pre-finishing welding process
The process of pre-finishing welding production: raw material inspection → feeding inspection → unwinding, butt welding → plate ultrasonic automatic flaw detection → milling edge → welded pipe forming → forming inspection → pre-welding → pipe cutting → internal cleaning → pre-weld inspection and repair → welding arc extinguishing plate → precision welding.
Statistics of pipe end defects
In the process of pre-finishing welding production of welded pipes, by sorting out X-ray inspection data, the number of pipe end defects in welded pipes within a period is counted, and its proportion of the total number of unqualified welded pipes is calculated. Pipe end defects seriously affect the quality of welded pipes and their qualified rate. Pipe end defects mainly include burn-through, pores, incomplete penetration, slag inclusion, welding deviation, etc.; among the three specifications of welded pipes with pipe end defects, the proportion of pipe end pores is 56.7%, 59.0%, and 62.5% respectively. Compared with other pipe end defects, pipe end pores are the most serious pipe end defects. Therefore, solving the problem of pores at the pipe end is the key to improving the quality of the pipe end of the pre-finished spiral seam welded pipe.
Solutions to pores at the pipe end
Based on the analysis of the causes of CO pores at the pipe end and combined with the production process of pre-finished welding, the following solutions are proposed:
① Ensure the appearance quality of the pre-welded weld at the steel pipe end, and grind or repair defects such as broken arc, burn-through, surface pores, and weld nodules;
② Remove iron oxide and other debris and dirt on the end face of the arc-initiating and extinguishing plate;
③ Remove impurities such as spatter, iron oxide, iron filings, and dust from the groove of the pipe end pre-weld, the surface of the parent material, and the end face of the steel pipe;
④After the arc-initiating and extinguishing plate is welded, grind the inner and outer welds at the joint of the arc-initiating and extinguishing plate to make the transition with the steel pipe weld uniform and smooth, and remove impurities such as spatter, iron oxide, iron filings, and dust generated during the joint;
⑤After the inner surface of the steel pipe is dusted by the fan, remove impurities such as iron filings and dust accumulated in the groove formed by the joint between the pipe end and the arc-initiating and extinguishing plate.
Conclusion
The defects of the welded pipe end directly affect the first-time qualified rate of welded pipes and the overall quality of welded pipes. By taking the above process measures, the pores at the ends of welded pipes are effectively solved, thereby improving the overall quality of spiral seam welded pipes and providing a guarantee for smooth production.
Post time: Oct-10-2024