Influence of the thickness of spiral steel pipe on welding quality
Burn-thru and hydrogen-prompted cracking in spiral metal pipe welding are warm subjects at domestic and abroad. There are many influencing elements of those problems, such as spiral metal pipe body, pre-weld treatment, welding procedure and post-weld treatment.(1) Spiral metal pipe body
1 wall thicknessIt is normally believed that the wall thickness of the spiral metal pipe exceeds 6.four mm to decrease the thickness of the fire-thru. ASME has finished studies at the minimal wall thickness of fueloline pipelines. Considering the elements of burn-thru, it's miles concluded that the minimal wall thickness of spiral metal pipe is associated with fueloline glide price and inner stress. Under a sure tube stress, the minimal wall thickness of the spiral metal pipe decreases with the growth of the fueloline glide price; whilst the fueloline glide price is constant, the minimal wall thickness of the pipe decreases with the growth of the inner stress of the pipe. The unique wall thickness records is proven in Table
1.1:WA Bruce et al. have proven that after restricting warmness input, pipes with wall thicknesses extra than 3.2 mm are much less liable to burn thru
. William Jarvis et al. studied that the minimal wall thickness perfect for warm-slot on line welding is four.eight mm. When the wall thickness of the spiral metal tube is much less than four mm, an inexpensive welding procedure can make sure a hit welding
.Influence of the thickness of spiral metal pipe on welding qualityThe SY/T 6554-2003 popular specifies that the minimal thickness of the bottom steel endorsed for maximum welds is four.eight mm. Considering the burn-thru factor, the real base fabric minimal wall thickness is the electricity layout wall thickness plus the protection margin (normally 2.4mm).2 medium glide priceIf the medium glide price is simply too fast, it's going to take extra warmness generated in the course of welding, beautify the warmth dissipation of the spiral metal pipe wall, growth the tendency of the welded joint to harden, and without difficulty result in hydrogen-prompted cracking; if the medium glide price is simply too slow, warmness can be concentrated, inflicting burn-thru. . Therefore, the media glide price need to be affordable to keep away from the prevalence of on line welding problems.In overseas nations, overseas nations do now no longer specify the medium glide price at the same old level.
The literature states:
1) Higher medium glide price will do away with warmness extra quick and decrease the opportunity of burn-thru;
2) Reasonable medium glide price can lessen burn-thru and hydrogen-prompted The opportunity of cracking. In the home aspect, there's an corporation popular that the glide price of the liquid medium withinside the pipe does now no longer exceed 2 m/s or the glide price of the fueloline medium does now no longer exceed 7 m/s. The welding may be finished after Sun Hua
 research that the glide price of the liquid medium isn't always extra than five m/ s; the fueloline medium glide price isn't always extra than 10m / s. Yang Jingshun
 notion that after welding welded pipe fittings on spiral metal pipes, there need to be a few regulations at the glide pace of the medium withinside the pipes. The medium glide price need to make sure that the welding procedure can meet the necessities of applicable technical regulations. It may be visible that the home facet has studied the medium glide price however there's no unified statement.