Triple eccentric valves play a key role in high-temperature, high-pressure, and highly corrosive working conditions in petrochemical, electric power, and metallurgical industries. Their sealing surfaces often fail after long-term operation due to wear, corrosion, and erosion.Traditional repair methods often have a limited service life, while plasma transfer arc welding (PTAW) technology has become the preferred solution for repairing triple eccentric valve sealing surfaces due to its high bonding strength and wear and corrosion resistance.
What is plasma transfer arc welding (PTAW)?
Plasma transfer arc welding is a high energy density powder metallurgy welding technology. The principle is to use a plasma arc to melt alloy powder (such as cobalt-based alloy, nickel-based alloy, stainless steel powder, etc.) and spray it at high speed onto the surface of the workpiece under the action of protective gas to form a metallurgical bond layer with low dilution rate with the base metal. This bonding method ensures that the overlay layer possesses high strength, density, and excellent wear and corrosion resistance, making it highly suitable for wear-resistant treatment of high-temperature, high-pressure valves.
Typical applications of PTAW on triple eccentric valves
In the repair of triple eccentric valve sealing pairs, PTAW is mainly used for:
- Valve seat sealing surface build-up welding: to form a high-hardness wear-resistant layer.
- Valve plate sealing ring cladding: to reduce friction and improve sealing reliability.
- Sleeve and support surface reinforcement: to prevent leakage caused by gap expansion.
Advantages of plasma transfer arc welding
Compared with traditional welding methods, PTAW has the following significant advantages in the repair of triple eccentric valves:
• High bonding strength: Metallurgical bonding method prevents coating peeling.
• Low dilution rate: Generally 3%–5%, coating performance is close to the original performance of the powder.
• Dense coating: Low porosity and strong corrosion resistance.
• Excellent wear resistance: Especially the cobalt-based alloy valve welding layer, which is suitable for erosion and friction environments.
• High processing precision: Coating thickness and position are controllable, with a small heat-affected zone, minimizing deformation.
• Adaptable to complex structures: Can precisely cover complex sealing surfaces such as the conical and annular surfaces of three-offset valves.
PTA welding process for triple eccentric valve sealing surfaces
1. Surface pretreatment: Clean the sealing surface and remove oil stains, rust, and oxidation layers.
2. Positioning and clamping: Ensure that the workpiece is accurately fixed on the CNC equipment or special welding machine.
3. PTA welding: Set parameters such as welding current, powder feed rate, and welding speed according to the valve material and powder characteristics.
4. Cooling and cleaning: Control the cooling speed and remove surface spatter.
5. Machining and grinding: Restore the dimensional accuracy and roughness of the sealing surface.
6. Quality inspection: Includes hardness testing, penetrant testing, and sealing performance verification.
Why choose PTA welding to repair triple eccentric valves?
Plasma transfer arc welding provides a high-performance, long-life solution for manufacturing and repairing the sealing surfaces of triple eccentric valves. Not only does it restore the dimensions and performance of the sealing surface, it also significantly improves its wear, corrosion, and erosion resistance.
For more information on how plasma transfer arc welding can repair triple eccentric valves, or to discuss your specific repair needs, email us! Our team of experts is ready to provide customized solutions for your specific application.
Post time: Aug-15-2025