Valve Coating
A paradigm shift in severe service valve trim for HPAL & POX applications
In High-Pressure Acid Leaching
( HPAL) and Pressure
Oxidation( POX) applications, valve trim performance is critical to ensure reliable operation under extreme conditions. Traditional coatings often fail prematurely, leading to costly downtime and maintenance. This article introduces an advanced ball valve trim technology that significantly outperforms conventional coatings, offering superior wear and corrosion resistance for enhanced reliability and reduced operational costs.
Figure 1 FM-1500 TM installation visualised within operational configuration.
The critical need for high-performance valve trim in HPAL & POX
In the demanding world of High-Pressure Acid Leaching( HPAL) and Pressure Oxidation( POX), ball valves are crucial for slurry isolation and process control. Ball valves used in these conditions must endure repeated cycling, differential pressures and continuous exposure to aggressive media. Standard valve trim solutions, such as thermal spray coatings, often fail prematurely due to coating delamination, corrosion and erosion, leading to inferior valve sealing performance, frequent unplanned maintenance, costly replacements and process downtime. These systems operate under extreme conditions, including:
• Temperatures reaching 270 ° C
• Pressures exceeding 4,500 kPa
• Exposure to high velocity abrasive and corrosive acidic slurries
Challenges of traditional coatings applied on valve trim in HPAL & POX applications
1. Rapid degradation of thermal spray coatings Traditionally, atmospheric plasma spray oxide coatings are applied on the ball and seats to enhance wear resistance in severe service ball valves. However, these thermal spray ceramic coatings suffer from several inherent limitations:
• Mechanical bonding issues: thermal spray coatings are mechanically adhered to the substrate, making them prone to delamination and stripped off under high-stress conditions, resulting in loss of sealing efficiency.
By Evelyn Ng, Callidus Group
To address these challenges and overcome the failure mechanisms observed with the use of thermal spray coatings, Callidus Group developed( Fig 2), an advanced, surface-modified ball valve trim that revolutionises valve performance in HPAL and POX environments. This cuttingedge technology utilises multi-patented metallurgically bonded titanium nitride, offering excellent wear and corrosion resistance, extending service life up to five times longer than conventional coatings.
Figure 2 FM-1500 TM valve trim.
36 Valve World May 2025 www. valve-world. net