The technical requirements for welded pipes mainly include the following aspects:
Welding process assessment: Before welding the pipeline, the welding process should be assessed to determine the pressure range and bearing capacity of the welded joint to ensure the safety of the pipeline. The welding process of steel pipelines should comply with the relevant welding regulations and standards of JB4708, and pipelines made of non-ferrous metals should comply with the corresponding welding standards.
Qualification of welding personnel: Workers who perform pipeline welding must have relevant professional qualifications and be skilled. Welding workers who are not from the unit cannot be hired at will.
Welding methods: Commonly used welding methods include manual arc welding and carbon dioxide gas shielded welding. Manual arc welding is often used for welding of outdoor pipelines because of its flexibility and low equipment requirements.
Welding materials and equipment: Choosing appropriate welding materials and equipment is the key to ensuring welding quality. For example, using mixed gas (such as Ar+CO2 mixed ratio 80%∶20%) can make the welding arc more stable and reduce spatter.
Technical requirements during welding: During welding, attention should be paid to details such as the position of the arc point, the length of the welding arc, and the formation of the weld. For example, each arc point welding should be performed continuously at a distance of 1 to 2 mm from the bottom to ensure the normal formation of the weld on the back.
Post-welding treatment and inspection: After welding, the weld should be polished and smoothed, and tested to ensure that there are no defects or cracks on the welding surface. The welded pipe should be inspected by professionals and can only be used if it meets national standards.
