Structural steel pipe in its wall thickness, good materials, processing technology and stability, becoming the first choice for large domestic and foreign oil and gas pipe project. In the large-straight seam welded steel pipe joint structure, weld and heat affected zone is the easiest place to produce a variety of defects, and weld undercut, pores, slag, lack of fusion, lack of penetration, weld, burn, weld cracking is the main form of welding defects, and are often the cause structural steel quality accidents origin.
Structural steel quality control measures include:
Prior to welding quality control
1. Make a good quality of raw materials, after passing inspection before being officially entered the construction site, and resolutely put an end to the use of substandard steel.
2, Followed by the management of welding materials. Check whether the welding materials for qualified products, storage and baking system if implemented, whether to issue a welding material surface clean and free of rust, electrode coating is intact, with or without mildew.
3, Welding area clean management. Clean quality inspection weld zone, without water, oil, rust and dirt oxide film, which is to prevent external weld defects produce important role.
4, Select the appropriate welding method should be implemented first test welding, after welding principles.
Quality control in the welding process
1, According to welding procedure specifications wire and flux review is correct, prevent misuse wire and flux caused by welding quality accident.
2, The welding environment supervision, take appropriate measures after welding when welding environment is not good (temperature below 0 ℃, relative humidity greater than 90%) should be.
3, Before the expected first test weld groove dimensions, including space, blunt edge, the angle and the wrong mouth, etc. meets the process requirements.
4, Inside and outside the submerged arc welding process chosen welding current, welding voltage, welding speed and other parameters are correct.
5. Supervise staff in the submerged arc welding inside and outside the welding arc full advantage of steel tube end plate length, straight seam steel strengthen the efficiency of the welding arc when the inner and outer plates, which helps to improve the quality of welding the pipe ends.
6, Supervise welding personnel in the welding slag clean whether first, whether the joint has been completely processed, whether the groove of the oil, rust, slag, water, paint and other contaminants.
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