Metal Seated Ball Valves and Knife Gate Valves for Severe Service Applications
Several recent pipeline shutdowns highlighted the serious consequences of unexpected downtime. No matter the size of your operation, keeping it running is extremely important.
You rely on valves to keep your system working. You count on efficiency and safety. When you need valves for a challenging environment, you can’t leave performance to chance.
Severe service valves are designed to give you maximum performance in the toughest conditions. Metal seated ball valves and knife gate valves are two types of valves ideally suited for severe service conditions.
Find out more about using metal seated ball valves and knife gate valves. You’ll have the information you need to choose the best valve for your system.
When Do You Need Severe Service Valves?
Somewhat surprisingly, a standard for defining severe service valves doesn’t currently exist. People typically identify severe service valves by the applications they’re using the valves in.
Severe service conditions challenge the valve’s ability to provide optimum performance. Conditions that call for severe service valves include:
- Very high pressure
- Large pressure drops
- Extreme temperatures
- High vibration
- Corrosive environments
- Contaminated media
Outgassing is the release of trapped gas or vapor. It can cause a sudden increase in the flow volume.
Some industries frequently use severe service valves. These industries include:
- Pulp and paper
- Power generation
- Oil and gas
Using a valve that will maintain its performance in severe service conditions is very important. If the valve isn’t durable enough, your repair and maintenance costs will be higher. You could be putting your facilities, equipment, and personnel in danger.
Severe service valves are durable. They should need as little maintenance as possible with few repairs. They need to perform consistently to high standards even in difficult conditions.
Metal seated ball valves and knife gate valves meet these criteria.
What Are Metal Seated Ball Valves?
Ball valves are a type of shutoff valve. They control the flow of a liquid or gas.
How Does a Ball Valve Work?
Ball valves open and close with a quarter turn. A rotary ball with a hole (bore) in the middle lets the liquid or gas flow through or stops it from flowing.
Seats support the ball and make a seal between the ball and the valve body.
A stem connects the ball to an external control mechanism. Ball valves can use mechanisms including a handle or lever. Turning the stem turns the rotary ball to open and close the valve.
Metal Seated Ball Valves
Ball valves can have either soft seats or metal seats. Metal seats make the valves able to handle severe service conditions. Metal seats are made from materials like copper alloy, chrome stainless steel, or nickel-based alloys.
Metal seated ball valves can withstand high temperatures. Depending on the materials, they can support up to 1500ºF. They’re resistant to abrasive and corrosive media.
Metal seated ball valves can handle high-pressure applications. They will also withstand flashing and hydraulic shock.
Coatings for Severe Service
For even greater durability, you can apply a coating to metal seated ball valves. Some common coatings are:
- Chromium carbide
- Tungsten carbide
- Chrome oxide
- Titanium dioxide
Chromium carbide and tungsten carbide are high-velocity oxygen fuel (HVOF) overlays. Chrome oxide and titanium dioxide are ceramic overlays. Each type of coating will give you specific benefits, like increased resistance to corrosion, abrasion, or heat.
What Is a Knife Gate Valve?
Knife gate valves are best suited for on-off applications and isolation services.
Knife gate valves developed in the pulp and paper industry. Processors needed a valve that could handle the fibers in the fluid. Knife gate valves get their name from their ability to cut through those solids.
Knife gate valves work by lifting a gate out of the path of the media. The media and solids flow easily over soft seals.
The gate is sharp. When the valve closes, it chops up the solids. This allows the valve to fully close instead of becoming blocked by the solids.
Preventing Leakage and Emissions
Early versions of knife gate valves had problems with leaks, emissions, and discharge. Modern knife gate valves are zero-leakage. They have an axial seated design and gate guides.
Gate guides prevent the gate from deflecting when it encounters solids.
Severe service knife gate valves have a secondary seal to back up the primary seal. Additional transverse seals help prevent emissions.
Severe service knife gate valves are made from materials that will withstand demanding conditions. The valve bodies are often stainless steel or carbon steel.
Severe service knife gate valves usually have metal seats. Ni-hard wear rings offer further protection in extreme conditions.
Benefits of Knife Gate Valves
Knife gate valves are especially well-suited for systems with a high level of suspended solids. They are ideal for slurry. They can withstand corrosive and abrasive media.
Knife gate valves are easy to actuate. They’re relatively light compared to other severe service valves. They’re also cost-effective.
Metal Seated Ball Valves vs Knife Gate Valves
Metal seated ball valves and knife gate valves can handle severe service conditions. The type of valve you choose depends on your application.
Both types of valves can handle corrosion and abrasion. They perform well in high-pressure applications.
Metal seated ball valves and knife gate valves can withstand high temperatures. The level of temperature resistance depends on the material.
If you need a valve for a system with thick media, though, you need a knife gate valve.
Finding Your Severe Service Valve Supplier
When you need valves for your severe service applications, you only want the best. Anything Flows has years of experience developing tailor-made flow control solutions.
We supply the highest quality products available. More importantly, we’re dedicated to giving you the best service and support. Whether you need metal seated ball valves or knife gate valves, we’ll help you find the right solution.
Contact us today for all of your severe service needs.