What qualifications are required for welding copper pipes with a design pressure of 1.6 Mpa and an actual operating pressure of 1.0 Mpa? What kind of flaw detection?

This post was last edited by Shutong on 2020-10-17 at 19:07. 1. A certificate for welding personnel issued by the Market Supervision Bureau is required, as it involves pressure pipelines. Tungsten inert gas welding of red copper is very difficult. In the past, welding wires containing Si and Mn were used for deoxidation; although this improved the porosity in the welds, it was hard to eliminate porosity completely. During TIG welding, N is also one of the causes of porosity; as the nitrogen content in the argon gas increases, the number of pores in the weld increases accordingly. Although N is insoluble in copper below 1400°C, the molten pool beneath the arc is at a high temperature, allowing some N to dissolve into it, thereby increasing the partial pressure of N in the arc atmosphere and leading to an increase in the number of N pores. The use of welding wires containing appropriate amounts of denitrogenation elements (Ti, Al), such as copper welding wires with 0.20% Al and 0.10% Ti, can prevent the formation of nitrogen pores. Ti and Al are strong deoxidizers, and they are also effective in preventing vapor pores in welds. 2. Perform radiographic testing. 3. Since it is a pressure pipeline, a hydrostatic test should be carried out.