Pressure pipe welding quality control
The welding process is the key process of the construction of the pressure pipe and the main process. The pressure pipeline group, the welding quality is good or bad directly affect the pipeline flow direction of medium flow rate, pipe wear and safe operation. It has very strict requirements for pressure pipe welding quality, in addition to the requirements of the welded joints for full penetration welds the pressure pipeline corrosion resistance as well as the quality of weld that also has a specific welding standards, weld surface ( tank, outside) should be smooth, uniform, no obvious punch weld. The quality of the welding process control plays an important role to ensure the installation of pressure pipelines. To this end, the control of welding quality is good pressure in the pipeline project pipeline installation quality control.
Preparation before welding
Pressure pipe welding required for manual arc welding machine, welding machine, the electrode drying equipment and weld heat treatment device should be complete and intact, stable and reliable performance, should be fitted in the (school) during the period of the weekly inspection qualified current, voltage table, the pressure gauge. The beveling and clean up the site conditions allow, should maximize the use of plasma arc, oxyacetylene thermal processing methods. Groove processing is completed, you must remove the surface layer of oxide, oil, slag and affect the quality of the joint groove that clear range not less than 20mm area groove on both sides of the base metal, and should asperities polished smooth.
Control of the welding process
Materials and welding consumables. Construction units should have a comprehensive materials management system, to ensure that the specifications of the material models meet the design requirements:
Site material: on-site materials member According to the information of checked material arrival certificate name, specifications, model, quantity and quality of proof is consistent with the physical. Passed the test materials, on-site materials is responsible for warehousing and on account of its registration. Sometimes the scene of some of the material specifications can not be stored in the coffers, it should select a suitable open space storage and protection work. The material must be deposited into the Treasury warehousing safekeeping, to prevent loss and damage. Material release, be sure to check the material of the project, specifications, models, materials and quantities to prevent wrong. The site of the electrodes used must be dried, the operator with a cooler of recipients, to prevent damp. Each barrel only partake of the same grade of welding rod to prevent misuse, and a maximum of not more than 5kg bucket storage time should not exceed 4h, otherwise it must be re-drying. Wire once requisitioned shall not exceed the minimum packaging, should be checked prior to use to clean surface rust, oil and other impurities. TIG welding with argon gas should be not less than 99.9% purity and water content of not more than 50ml/m3.
Process materials: pipe installation process, some of the materials required by the number of procedures of processing before installation, such as pipes and weldments different according to the medium, subject opening, open groove, rust removal, pickling, blunt processing, degreasing processes; valves, fittings, instrumentation, subject to cleaning, degreasing, inspection, testing and other processes processing; protective treatment must be done between the various processes, and the handover inspection work to do between the various processes, in order to prevent recontamination.