Oil Leakage at Welding Joints
This issue is primarily caused by poor welding quality, including factors like incomplete welds, detachment, and the presence of defects such as pinholes and blowholes in the weld seams. Oil-immersed transformers are initially covered with welding compounds and paint during production, but these issues may surface during operation. Electromagnetic vibrations can also lead to weld cracking, resulting in oil leakage.
To address existing leaks, it's crucial to locate the leakage points. For severe leaks, metal tools like chisels or punches can be used to rivet the leakage points, controlling the oil leakage.Afterward, the affected surface should be thoroughly cleaned, and high-polymer composite materials are often used for sealing, achieving a long-term solution for oil leakage.
Seal Leakage
Poor sealing typically results from inadequate handling of the joints between the transformer's casing and the cover. Rubber rods or rubber gaskets are commonly used for sealing the casing edges and cover. If these junctions are not properly managed, it can lead to oil leakage problems. Some may use plastic straps, while others might press the two ends together directly. Inadequate sealing during installation, due to rolling or improper pressure, can lead to a lack of airtightness, resulting in oil leakage. The use of Foshilin materials for bonding these junctions to create a solid, leak-resistant structure can be effective. If feasible, it's also possible to bond the metal casing for added leak control.
Oil Leakage at Flange Connections
Surface irregularities in flanges, loose fastening bolts, or incorrect installation practices can lead to insufficient bolt tightening, causing oil leakage. First, secure the loose bolts and proceed to seal the flange properly. Consider any bolts that might be prone to leaks, and ensure they are also properly addressed, achieving complete leak control. The tightening of loose bolts must strictly follow the operational process.
Bolt or Pipe Thread Oil Leakage
Rough processing during manufacturing or poor sealing can lead to oil leakage after some time in oil-immersed transformers.
Using high-polymer materials to seal the bolts can effectively control leaks. Another method involves removing the bolt (or nut), applying Foshilin mold release agent on the surface, applying sealing material, and tightening it, followed by curing to achieve the control goal.
Cast Iron Component Oil Leakage
Oil leakage in cast iron components is mainly caused by sandholes and cracks.
To address leakages resulting from cracks, drilling stop holes is the best method to eliminate stress and prevent further extension of the cracks. In the repair process, lead wire can be inserted at the leakage point or hammered with a hand tool. Afterward, clean the leakage point with acetone and apply sealing material. For cast iron with sandholes, direct sealing with material is a suitable approach.
Radiator Oil Leakage
Radiator oil leakage commonly occurs in the bent and welded sections of the heat pipes. This is due to residual stresses resulting from the bending and stamping of the radiator tubes, where the outer wall is under tension and the inner wall is under compression.
To address this, close the radiator's upper and lower flat valves (butterfly valves), isolating the oil inside the radiator from the oil in the tank. This reduces pressure and leakage. Once the leakage points are determined, apply the appropriate surface treatment and use Foshilin materials for sealing and repair.
Porcelain Bushings and Glass Oil Gauges Leakage
These issues usually arise from improper installation or seal failure.
High-polymer composite materials can effectively bond materials such as metal, ceramics, and glass, providing a comprehensive solution for oil leakage in oil-immersed transformers.
