Valves and valve components are subject to wear, erosion and corrosion from the harsh environment they operate in. A valve breakdown could lead to thousands of tonnes of material being lost, causing environmental damage, material contamination, health and safety risks, and system failures. The primary causes of such failures include wear of the valves, the valve seats, and associated components through cavitation and erosive wear.

Erosion is material weight loss caused by the process flow, especially if the fluid contains particles.

Corrosion can accelerate the erosion, and even a material that is completely resistant to erosion and corrosion may fail due to galling.

Galling is a form of wear caused by adhesion between two sliding surfaces and usually occurs when components that have similar hardness slide over one another in a dry or non-lubricating fluid condition.

Cavitation happens when the pressure in a liquid suddenly drops and bubbles of vapor form in the liquid. When the bubbles collapse, this creates pressure waves that can damage the valve internals. Cavitation can produce irregular pits and erosion inside the valve, as well as noise and vibration.

Replacement parts in exotic materials or even in standard materials can be costly, often requiring long lead times and months to be delivered, as well as the very real risk of excessive plant downtime.

Weld overlay cladding and hard facing are two commonly used methods for protecting valve internal surfaces from these types of damage

AOS Engineering has pertnered up with Welding Alloys to provide both cladding and hardfacing services for Industrial valves. The material most often used for hardfacing valve internals is Stellite 6, a cobalt alloy that contains chromium, tungsten, carbon and other elements

Hard facing offers several advantages, including:

1. Excellent wear resistance: The hard facing layer provides superior wear resistance, which can extend the life of the component in high-wear environments.

2. High hardness: The hard facing layer is typically much harder than the base material, which can help prevent surface damage and extend the life of the component.

3. Low cost: Hard facing can be less expensive than to replace components of valves