Appearance inspection requirements and standards for steel pipe welds

Steel pipe welds are the joints formed by welding of welded parts.

First, the classification of steel pipe welds
1. Steel pipe welds can generally be divided into: flat welds, fillet welds, single-sided welds, single-sided welded double-sided formed welds.
2. According to the different cross-sectional forms of the steel pipe welds themselves, steel pipe welds can also be divided into butt welds and fillet welds.
3. Steel pipe butt welds: The butt welds of steel pipes that are not fully welded are subjected to very little force and have serious stress concentration. The butt welds of steel pipes that are fully welded are referred to as steel pipe butt welds.
4. Fillet welds of steel pipes: The edges of the connecting plates do not need to be finely processed, the plates have no gaps, and the weld metal of the steel pipe is directly filled in the right angle or bevel area formed by the two welds. Carrying out appearance inspection of steel pipe welds can guide the work of welders and welding inspectors to ensure the welding quality of the entire work and project.

Second, the appearance inspection items of steel pipe welding
1. Various welding defects
- Undercut: Due to improper selection of welding parameters or incorrect operation process, grooves or depressions are generated in the parent material of the weld toe.
- Surface pores of steel pipe welds: During welding, bubbles in the molten pool are not removed during solidification, resulting in residual holes, which are pores.
- Unfused steel pipes: During fusion welding, the parts between the weld and the wood (between welds) that have not been completely melted and bonded, and the parts between the parent materials and the parent materials that have not been completely melted and bonded during spot welding.
- Incompletely welded steel pipes: The phenomenon is that the root of the joint is not completely melted during welding.
- Cracks in steel pipes: Under the combined action of welding stress and other brittle factors, the metal atomic bonds in the local area of the welded joint are destroyed, forming new steel pipe welds. Generally speaking, they have the characteristics of sharp notches and large aspect ratios.
- Incompletely welded steel pipe: This is the case when the filling metal is insufficient, and continuous or intermittent grooves are formed on the surface of the steel pipe weld.
- Weld nodule steel pipe: During the welding process, the molten metal flows to the unmelted parent material outside the steel pipe weld, resulting in the formation of metal nodules.
- Steel pipe burn-through: During the welding process, the molten metal flows out from the back of the groove, forming a perforation defect.

2. Various steel pipe weld shape defect phenomena
- Poor steel pipe weld forming: During fusion welding, the weld shape formed after the liquid weld metal condenses is called steel pipe weld forming. In a simple sense, poor steel pipe weld forming refers to the appearance of the steel pipe weld, the height of the steel pipe weld is different, the width of the steel pipe weld is uneven, or even no steel pipe weld corrugation, etc.
- Steel pipe weld leg size: In the cross section of the steel pipe fillet weld, the length of the right angle side is drawn in the largest isosceles triangle. The defect is manifested in the weld leg size being smaller than the design requirement and the weld leg size being unequal.
- Excessive residual height of steel pipe: the residual height is higher than the requirement or lower than the parent material.
- Welding leakage of steel pipe: the weld of the steel pipe required to be welded is not welded, which is specifically manifested in that the weld of the entire steel pipe is not welded, the weld part of the entire steel pipe is not welded, the arc pit is not filled, and the weld of the steel pipe is not filled and welded. In addition, there are defects in the shape of the weld of the steel pipe such as spatter and arc scratches.

3. Grinding of weld seams of steel pipes
There is a common understanding that the weld seams of steel pipes must meet the inspection standards after grinding. The weld seams of steel pipes must not damage the parent material when the weld seams of steel pipes are smoothly transitioned or smoothly transitioned with the parent material.

Third, summary
Welding is an important link in the production process of components, so in addition to inspecting and controlling the appearance of the weld seams of steel pipes, the welding quality must also be supervised and controlled. For specific products, auxiliary inspection measures should be taken when necessary.