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High Temperature Ball Valve 

April 24, 2022

What is a high-temperature ball valve? 

High-temperature ball valves are valves that can work at very high temperatures above 400 oC. High-temperature ball valves should be made of very strong metallic materials that have high melting point. Some metallic materials such as aluminum alloys start weakening as the temperature increases. Materials like bronze is not recommended for use as a high-temperature ball valve since as the temperature rises it changes its properties which can alter the fluid being controlled. When selecting a high-temperature ball valve the first thing to consider is the materials used to make that valve. This is the expected working temperature of that high-temperature ball valve that must be compatible with the internal components and body of the valve. The internal components of the valve must also be made of very strong metallic materials with high melting point. High-temperature ball valves are used in applications such as petrochemical, fertilizer, chemical, metallurgy, and electric power industries. The most common metallic material that guarantees reliable working when used to make high-temperature ball valve is carbon steel and stainless steel which have high melting points of 1425 oC to 1540°C to 1400 oC to 1530°C respectively. High-temperature ball valves are either manual or operated using an actuator. The valves are connected to the pipeline by using bolts and nuts or through the welding method. 

 

How does a high-temperature ball valve work? 

High-temperature ball valve consists of a ball with a bore at its middle section. The high-temperature ball valve is operated by using a handwheel, hand lever, or actuator. The handwheel and hand lever are used for manual valves while the actuator is used for actuated ball valves. The handwheel or actuator is connected to the ball through a component known as the stem. To open a high-temperature ball valve, the handwheel or hand lever, or actuator rotates. The rotational force is transmitted to the ball through the valve stem which makes the ball bore be rotated and be in line with the pipeline. Once the ball bore in the high-temperature ball valve becomes collinear with the pipeline fluid flows as it is not blocked by the ball. To close the high-temperature ball valve, the hand lever or handwheel, or actuator rotates in the opposite direction to the direction it rotated when it was opening. This makes the ball bore of the high-temperature ball valve to rotate and become perpendicular to the pipeline. In this case, the ball blocks the fluid from the pipeline and thus the high-temperature ball valve is said to be in a closed state. 

Working of a high temperature ball valve

Figure: Working of a high temperature ball valve.

 

Types of high-temperature ball valve

Two-piece high-temperature ball valve 

This is a high-temperature ball valve which has its body made of two pieces. The two pieces are fitted together using threads, weld or bolts and nuts connection. One of the two pieces of a high-temperature ball valve constitutes one end joint and the ball while the second piece constitutes the internal parts and the other end joint. The two-piece high-temperature ball valve is very common in the market and industrial applications because it can be disassembled for inspection, cleaning, repair, and maintenance. Also, this valve is small in size and light in weight relative to other ball valves.

Two-piece high temperature ball valve

Figure: Two-piece high temperature ball valve.

Three-piece high-temperature ball valve 

This is a high-temperature ball valve with three pieces. The three pieces consists of the valve body and two end joints. The three pieces are held together using bolts and nuts as shown in the figure below. The ends of the three-piece high-temperature ball valve are fitted to the pipeline either through welding, bolts, or threading. Three-piece high-temperature ball valves can be easily cleaned, inspected, and repaired while connected to the pipeline without having to remove them. The three-piece high-temperature ball valve is suitable for use in applications that need frequent repair and maintenance or that need high levels of hygiene such as pharmaceuticals, foods, and beverages as they can be effectively and easily cleaned. 

Three-piece high temperature ball valve

Figure: Three-piece high temperature ball valve.

Side entry high-temperature ball valve 

These are high-temperature ball valves that are assembled from the sides as shown in the figure below. Side entry high-temperature ball valves are large-sized ball valves made of strong metallic materials to help them work in high-temperature and high-pressure applications. Such applications where side entry high-temperature ball valves are used include petrochemical industries, oil, gas, and steam power plants. Side entry high-temperature ball valves consist of two or three pieces. The pieces are made through the forging method. After the pieces are produced, they are assembled using bolts and nuts to form the final product of the side entry high-temperature ball valve. One of the advantages of a side entry ball valve is that it can be inspected, cleaned, and repaired while it is in the field. Also, the internal components of the valve can be aligned with ease.

Side entry high temperature ball valve

Figure: Side entry high temperature ball valve.

Top entry high-temperature ball valve 

This is a high-temperature ball valve that is assembled from the top side. Top entry ball valves are manufactured through casting method. This helps to reduce chances of fluid leakage. The valve body and bonnet are connected at the top side. Top entry high temperature ball valves make it easier to do inspection, cleaning, and repair from the top side without removing the valve from the pipeline. Top entry high-temperature ball valves undergo non-destructive tests to ensure that they are free from defects that can result in fluid leakage while in use. Top entry ball valves are connected to the pipeline using bolts or through welding. Top entry ball valves are suitable for use in applications that need strong valves that are fire-proof or valves where high levels of hygiene can be maintained through regular cleaning. 

Top entry high temperature ball valve

Figure: Top entry high temperature ball valve.

Welded body high-temperature ball valves 

Welded body high-temperature ball valves are ball valves that are assembled through welding method. The body of this high-temperature ball valve is constructed by connecting all the pieces through welding. After the body is welded, a non-destructive test is conducted along the perimeter of the valve body on the welded joints to ensure there are no defects that can cause fluid leakage. 

One of the main challenges associated with welded body high-temperature ball valve is that it cannot be cleaned, repaired, or inspected while in the field. These valves are used in applications where no maintenance is expected for example in subsea and gas transmission systems among others. 

Side enWelded body high temperature ball valvetry high temperature ball valve

Figure: Welded body high temperature ball valve.

Full port high-temperature ball valve 

This is a high-temperature ball valve that has a ball bore diameter of the same size as the pipe diameter. With a full port high-temperature ball valve, there are no friction losses which makes it energy efficient. The design of a full port high-temperature ball valve makes it easier to clean. The challenge associated with this valve is that the ball and valve body are bigger relative to the standard port valves. As such, full port high-temperature ball valves are more expensive relative to the standard or reduced bore valves. Full port high-temperature ball valves are used where low fluid resistance is required for example in pump suction pipelines where the drop in pressure affects pump performance. Also, the full port high-temperature ball valve is suitable for use in applications where the fluid is likely to contain solids that can build up and clog the valve. 

Full port high temperature ball valve

Figure: Full port high temperature ball valve.

Reduced port high-temperature ball valves 

These are high-temperature ball valves that have a ball bore diameter less than the pipe diameter. Reduce bore high-temperature ball valves have high frictional losses and turbulence due to the unstreamlined flow created by difference in diameter of the pipe and ball bore. Reduced port high-temperature ball valves are suitable for use in cases where pressure loss and flow turbulence are not major concerns in the flow. The main advantage of using a reduced port high-temperature ball valve is that they are of smaller size which makes their cost lower relative to the full port counterparts. 

 

Applications of high-temperature ball valves 

  • High-temperature ball valves are used in crude oil industries for on and off applications that need high temperatures for separating different products of crude oil. 
  • They are used in steam power plants to generate electricity. 
  • High-temperature ball valves are used in the oil and gas industries.
  • These valves are used in the production of fertilizer. 
  • High-temperature ball valves are used in metallurgical steel production processes. 
  • High-temperature ball valves are used in food and beverages processing. 
  • They are used in pharmaceutical industries for their ease of cleaning.

 

Advantages of high-temperature ball valves 

  • High-temperature ball valves can withstand high temperatures without being distorted by thermal heat. 
  • High-temperature ball valves are durable. 
  • These valves are versatile as they can be used to serve in different applications. 
  • High-temperature ball valves can be cleaned, repaired, and inspected. 
  • High-temperature ball valves are quick to operate. 
  • These valves are strong enough to withstand high pressure. 
  • They have a perfect seal free from fluid leakage. 
  • High-temperature ball valves can be operated manually or by using an actuator. 

 

Disadvantages of high-temperature ball valves 

  • High-temperature ball valves are not suitable for throttling applications. 
  • These valves close and open quickly which makes them generate water hammers and overpressure problems. 
  • High-temperature ball valves must be installed vertically. 
  • Cavities around seats and balls tend to cause blockage due to solids which can increase opening/closing torque and or cause valve failure. 

 

Troubleshooting high-temperature ball valve 

Fluid leakage when the valve is closed 

  • Damaged sealing surface. Repair or replace the sealing surface. 
  • Seat damaged. Repair or replace the seat. 
  • Actuator or gearbox (for manual valves) not correctly adjusted. Adjust the actuator or gearbox timing. 

Unsmooth ball operation 

  • Foreign materials between the seat and the ball or between the body cavity and the ball. Disassemble the valve and clean the cavity, seat, and ball. 

The high-temperature ball valve is difficult to open/close

  • The seat is damaged. Replace the seat. 
  • Valve experiences high internal temperature. Check the valve working temperature as recommended by the ball valve manufacturer
  • Foreign materials clogged the body cavity. Disassemble the valve and clean the materials. 

Stem leakage 

  • Loose flange bolts. Tighten the flange bolts. 
  • Sealing surface damaged. Replace the sealing surface. 

Leakage from the pipe or valve and pipe joint 

  • Loose pipe-valve joint. Tighten the joint connection either threads or bolts and nuts. 
  • Foreign objects in the pipe. Check the pipe for any blockage and clean them. 

 

Summary 

High-temperature ball valves are valves that can work at high temperatures from 400 oC without undergoing chemical or thermal changes. High-temperature ball valves are made of metallic materials with high strength and high melting points. Such materials include stainless steel and carbon steel. High-temperature ball valves can be manual or actuated valves. High-temperature ball valves are fireproof to ensure they can withstand high temperatures even when used to control flow of flammable products. High-temperature ball valves are connected to the pipeline using threads, bolts and nuts or by being welded to the pipeline. High-temperature ball valves are used in different applications such as in oil and gas, petrochemical applications, fertilizer, steam power plants, metallurgy, and chemical industries among others. The various types of high-temperature ball valves include a two-piece high-temperature ball valve, three-piece high-temperature ball valve, side entry high-temperature ball valve, top entry high-temperature ball valve, and welded body high-temperature ball valve, full port high-temperature ball valve and reduced port high-temperature ball valve. High-temperature ball valves have various advantages such as being quick to operate, durable, versatile, fire-proof, repairable, high strength, and leakage proof. 

 

 

 

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