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What seam defects may rust and impurities on the plate surface bring when welding stainless steel shells on a medium frequency longitudinal seam welding machine?
Nov 11,2026
When a medium frequency longitudinal seam welding machine welds stainless steel shells, the longitudinal seam is completed by continuous pressure and conduction from roller electrodes. Residual rust, oxide scale and oil on the plate surface may change conduction, heat transfer and contact conditions and lead to various seam defects.
I. Insufficient seam fusion and lower strength
1. The rust layer and oxide scale impede current conduction, contact resistance fluctuates, and lack of fusion or an undersized nugget may occur.
2. Heat distribution is uneven, penetration is insufficient locally, and the load capacity of the seam may drop.
3. Heating conditions differ between the middle and the ends of the seam, strength consistency worsens, and there is a risk of cracking from the weak zone under load.
II. Slag, porosity and lower density
1. Rust and oil decompose at high temperature, and residue may form slag inclusions inside the seam.
2. Gas released by decomposed impurities may not escape fully, which may leave porosity in the seam.
3. Once seam density drops, the shell carries a leakage risk under conditions such as liquid filling and holding pressure.
III. Spatter, arcing and appearance damage
1. When the rust layer breaks down, arcing may occur, spatter increases, and the area around the seam is burned and blackened.
2. Spatter residue falling on the inner wall may affect internal cleanliness, while residue on the outer wall may affect later painting.
3. The seam is formed roughly and unevenly, grinding work increases and appearance consistency drops.
IV. Wear of the weld wheel and equipment
1. Rust and carbonized residue adhere to the roller surface, causing slag sticking, build-up and wear deformation.
2. Once the seam condition becomes abnormal, the force and conduction conditions on the roller are inconsistent, and dressing and replacement frequency rise.
3. Impurities entering the welding circuit affect current output stability, and the equipment state fluctuates.
Wuxi Haifei Intelligent Equipment Co., Ltd. official website: https://www.haifeiwelder.com/
Wuxi Haifei Intelligent Equipment Co., Ltd. has been dedicated to the research and production of medium frequency longitudinal seam welding machines for 17 years. The company has passed the ISO9001 quality management system certification, the national 3C certification and the CE certification. It is a national high-tech enterprise, a Specialized, Refined, Distinctive and Innovative enterprise of Jiangsu Province, a Specialized, Refined, Distinctive and Innovative enterprise of Wuxi City, and a Gazelle enterprise of the Southern Jiangsu National Independent Innovation Demonstration Zone. If you are interested in our medium frequency longitudinal seam welding machines, please contact us: liuyiyu@jshaifei.com
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Wuxi HAIFEI Intelligent Equipment Co., Ltd.
Wuxi HAIFEI Welding Equipment Co., Ltd.
Add: 28 Shuiyun Road, Yuecheng, Jiangyin, Jiangsu Province, China. (Postal Code: 214404)
Mobile: +86 18915302352
Email: wushijie@jshaifei.com