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How to Prevent Weld Seepage & Rust When Welding Fuel Tanks with Medium Frequency Seam Welders
Jul 13,2026
Micro-hole oil seepage and weld rust on finished fuel tanks during medium frequency seam welding are not caused by base plate damage, but hidden welding defects plus inadequate post-weld anti-corrosion treatment.
I. Main Causes of Seepage & Rust
1. Causes of Oil Seepage
Most tank leakage stems from internal flaws from poor welding control. Unstable welding pressure, excessively fast travel speed and mismatched current create uneven, porous weld metal with tiny pores and interlayer gaps. These latent defects gradually form oil leakage channels under long-term pressure, vibration and temperature fluctuations. Meanwhile, oil stains, rust and dirt on plate surfaces vaporize at high temperature and generate pores, triggering seepage.
2. Causes of Weld Rust
High welding heat destroys the original anti-rust coating of steel plates, reducing corrosion resistance of welds and heat-affected zones. Oxide layers, fine ripples and micro-pores on weld surfaces easily trap moisture, oil and dust, corroding the metal over time, leading to yellowing, peeling and even perforation with oil leakage.
II Optimize Welding Process to Avoid Seepage
1.Stabilize welding pressure
Insufficient pressure fails to compact plate laps and creates loose gaps; excessive pressure thins plates and induces welding stress. Use moderate, stable pressure to fully squeeze lap gaps and achieve dense weld fusion.
2.Control reasonable travel speed
Over-fast speed causes incomplete fusion and discontinuous beads. Maintain constant, steady welding speed, avoid machine stalling and high-speed runs to form full, continuous welds and slow delayed seepage.
3.Match proper welding current
Low current results in weak fusion and oil seepage; high current overheats and creates porous welds with poor corrosion resistance. Adjust parameters until weld ripples are full, uniform without overburning blackening, ensuring sound internal metallurgical bonding.
4.Keep stable water cooling
Continuous welding accumulates heat on rollers, causing unstable machine output and inconsistent fusion. Maintain unobstructed constant-temperature water cooling to stabilize welding conditions.
5.Clean plates before welding
Oil, rust and scale on welding areas vaporize under heat and form pores. Thoroughly clean and dry surfaces pre-weld to reduce welding flaws and improve sealing performance.
III Process tweaks to lower rust risk
Avoid high-current overheating welding to reduce heat accumulation and shrink high-temperature oxidation zones, retaining base plate anti-rust performance. Calibrate rollers and optimize parameters to form flat, smooth welds with minimal concave/convex crevices that trap less moisture and grease, slowing corrosion.
IV Standard Post-Work to Eliminate Hidden Long-Term Risks
1.Grind and finish welds
Oxides, burrs and welding ash on fresh welds absorb moisture and rust easily. Light grinding to flatten surfaces, remove surface contaminants and expose dense solid metal substrate to cut corrosion risks.
2.Implement targeted weld anti-corrosion
Welds are the weakest anti-rust position. Apply independent sealing anti-rust coating to isolate air, moisture and oil and slow metal corrosion.
3.Keep tank interior dry
Water residue remains inside tanks after hydrostatic testing and corrodes inner welds over time. Fully blow dry internal water after testing to prevent internal rusting.
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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