Harm of oversize of weld seam The stress concentration of the butt joint is easily caused by the stress corrosion crack at the toe of the weld, which is mainly caused by the weld height. The stress at the weld toe of the butt joint is the largest. The larger the weld height is, the more serious the stress concentration is, and the strength of the welded joint will decrease. After welding, the cutting height is higher than that of the base metal, so that the stress concentration can be reduced. The outer weld is very large and is not good for anticorrosion If the epoxy resin glass cloth is used for corrosion prevention and the outer weld seam is large, the welding toe will not be firmly pressed. At the same time, the higher the weld is, the more the anticorrosion layer should be thickened, because the thickness of the anticorrosion layer is measured by the vertex of the outside weld, which increases the anticorrosion cost. Large internal weld seam increases energy loss of conveying medium. If the inner surface of the pipe welding pipe is not treated with coating anticorrosion, the remaining size of the inner weld is large, and the friction resistance of the conveying medium is great, thus the energy consumption of the pipeline will be increased. Control measures of weld seam height Adjust the energy of welding line Check the welding line energy is suitable, generally use the welding joint acid etching sample to check. One is to check the degree of reclosing of the inside and outside welds. The two is to check the width of the welds’ waist. The requirement for coincidence is generally greater than 1.5mm, but the author thinks that the coincidence between internal and external welds is more suitable for 1.3 ~ 3.0mm. If 3.0mm exceeds that, it means that the line energy is large. The line energy is large, not only the depth of fusion is large, but also the weld height is high. If the groove or U groove is not opened, the weld height will be larger. This is because the greater the energy of the welding line, the longer the welding wire will be in the unit time.