High Temperature Valves

What Defines a High-Temperature Valve?

When choosing a valve design and material selection, the working temperature of the valve should be compatible with the valve body and trim materials. High-Temperature Valves are found in the petrochemical, chemical, fertilizer, electric power, and metallurgy industries. The material properties of non-ferrous, carbon steel, and alloy grades, are specified according to the limits of the material. Bronze, for example, cannot exceed 550F degrees, therefore not considered high temperature. High-temperature grades are:

Sub-high temperature 

Sub-high temperature valves refer to the working temperature of the valve between 625f and 800f degrees. 

WCB, WCC, A105, WC6, and WC9 are mainly used for corrosive services in this range: C5, CF8, CF3, CF8M, and CF3M is used 

High-Temperature Level I

High-Temperature Level I is the working temperature of the valve within the range of 800f and 1025f degrees.

Materials within this range are based on CF8 Stainless steel in the ASTM A351 family. 

High-Temperature Level II and Level III

High-Temperature Level II and Level III are within the working temperatures of the valve within the range of 1025f and 1350 degrees.

Materials within this range are based on CF8 Stainless steel in the ASTM A351 family.

For Temperatures above 1350f, the working temperature of the valve is classified as high-temperature Class IV and Class V. This requires application-specific recommendations and cannot be quoted routinely as the pressure-temperature level may cause plastic deformation. 

Pressure /Temperature Matrix

Cast Steel or forged steel valves can be made of carbon steel or stainless steel alloys and trims are capable of handling 1000f degree temperatures at up to 10,000 psi. These valves are made with metal to metal full hard-faced seats, or various chrome-moly alloys and exotic materials like Monel 400, Hastelloy C276, Inconel 600, and Inconel 625.

How are valves specified for pressure-temperature?

ASME B16.34 Pressure Temperature Table groups materials by pressure and temperature for recommended application.

PECIFICATION GROUPS MATERIALS

For example, Gate valves, globe valves, stop-check valves, and Check valves have recommended material combinations based upon the ASME B16.34 Pressure Temperature Table. SA 182 F11, SA 182 F22, SA 182 F316, ASTM A351 CF8M, A 351 CN7M, C-276, A217 WC6, A217 WC9, A216 WCB, A352 LCB, A352 LCC, A352  LC2, A352 LC3, A217 WC1, A217 WC4, A217 WC6, A217 WC9, A 217 C5 all carry different capabilities for pressure, temperature and corrosion resistance. 

An additional factor determining valve limitations are packing and gasket materials, which can be made of Grafoil or Graphite for higher temperatures, Teflon for temperatures under 500F degrees, and high temperature two-ply and three-ply Monel bellows. 

Bellows Seal Valves

Bellows Seal Valve applications include power industry helium lines, high-pressure steam, vacuum, heavy water, hydrocarbons, argon, ammonia, benzene, caustic solutions, dowtherm, nitrogen, phosgene, sulfuric acid, toluene, cryogenic service, heat transfer oils, or other applications involving containment of fugitive emissions or protection from valve gland leakage. Body to bonnet connections can be ordered as bolted bonnet, sealed bonnet, welded bonnet, hermetically sealed bonnet, pressure seal bonnet, bellows seal bonnet, or union bonnet. Bodies can include by-passes or sampling valves with end connections in threaded NPT, butt-weld, socket weld, flanged ends, ring type joint, and raised or flat face. 

Pressure Seal Bonnet 

Pressure seal bonnets for high pressure / high-temperature applications, also known as Breech lock valves, have a seal weld in the bonnet. This is a feature designed for safety, seen in applications like steam and boiler feed water services, in compliance with ASME boiler and pressure vessel code applications, and the ANSI power piping code. Sizes and pressure classes of Pressure seal valves include all sizes from 3” to 24” pipe size in pressure class 300, 600, 800, 900, 1500, 2500, 4500, 6000, and 10,000.  To learn more about the manufacturers of high-temperature valves including Edward, Velan, Powell, Kitz, Lunkenheimer, Smith, Pacific, and many others, view Authorized Parts Technical Library.

Ball Valves for High-Temperature Applications

Ball valves are a cost-effective solution for stop valve applications with high temperatures. The high temperature for ball valves can be considered an operating temperature above 400°F, the threshold for Teflon seats. Ball Valve seats are the most vulnerable component of the valve. Metal-seated ball valves are specified at temperatures greater than 750°F. That presents the gap of options between Teflon seats at 400°F and the metal seats at 750F to the upper end of the range at 1,500°F. Seat material options between 400F and 750F include R-PTFE (RTFE), 15% glass-reinforced PTFE, is suitable for temperatures to 450F, PEEK material is good to 550F, High-Temperature Carbon Fiber / Graphite-filled TFM (PTFE) extends the maximum Operating Temperature to 580F, Carbon Graphite can be specified to 700F.

Pressure-temperature ratings are given for common materials in ASME B16.34, with the temperature of the shell assumed to be the temperature of the fluid. Trim components within the valve assembly must be capable of withstanding high stresses. The valve ball itself, and valve stem are subject to the high torque required to actuate the valve, so they should be made from a corrosion-resistant material that maintains high yield strength and torsional stiffness at elevated temperatures, such as Inconel 718, 17-4 stainless steel, or Nitronic 50.

High-Temperature Service

High-Temperature Steam Service has special qualities that need consideration. Saturated Steam (Dry), Unsaturated Steam (Wet), Superheated Steam, and Supercritical Water. As the temperature increases and the water approaches its boiling condition, some molecules attain enough kinetic energy to reach velocities that allow them to momentarily escape from the liquid into space above the surface, before falling back into the liquid. As the water is heated to its boiling point, bubbles of steam form within it and rise to break through the surface. When specifying a high temp valve, please identify which type of steam is in service.

Extreme Temperature Service 

Since 1995 Authorized Parts, Inc. has been a leader in the field of special valves for critical industrial applications. For extreme temperature valves for severe services, contact us with the type of product needed, specific functions required, your processes and applications, special material requirements including exotic alloys, service conditions, or particular technical issues and we will make a recommendation.

Bi-directional Flow

For definition when selecting a valve, in a unidirectional valve the medium can flow in only one direction. In a bidirectional valve, the medium can flow in both directions. A Gate valve is a bidirectional valve for example, but Globe and Check valves are unidirectional.

Maximum Pressure

In designing equipment, MAWP is the maximum pressure at which the vessel or equipment is allowed to function at a specific temperature. Design pressure is the condition of coincident temperature and pressure that is expected in a normal condition. The MAWP will be changing with time because of corrosion and vessel fatigue. Both the design pressure and MAWP should be estimated before selecting a product.

Pressure Ratings

Temperature is a factor in determining the pressure rating of valve flanges. Because metals are weaker at higher temperatures, for a given material, pressure ratings decrease as temperature increases. There is a great disparity in ratings for high-temp applications and low-temperature situations. Consult Authorized Parts, Inc. for your questions regarding pressure-temperature ratings. 

End Connections

Several factors influence the selection of valve end connections: Pressure Rating, Leakage Prevention,  ease of Installation, Repair and Replacement, Valve Integrity and Durability, Weight and Size, and cost.

Visit our Technical Library to explore which connection is best for your application: Threaded NPT, Socket Weld, Butt Weld, or Flanged.

Thermal Expansion

Authorized Parts, Inc. offers high-performance butterfly valves with metal seats.  These Valves are rated for services up to 700°F for bi-directional flow, with a disc is designed to reduce thermal expansion. The valve is available in both lug and wafer designs and in carbon and stainless steel. In addition, our high-pressure ball valves, cryogenic ball valves, metal seated ball valves, flanged ball valves, control valves can be modified to meet your specifications.

Special Applications

Contact Authorized Parts, Inc. for Custom valves for high temperature and high-pressure applications. Our severe service valves have special design features for the harshest applications in accordance with  API6A valve specifications. Design temperatures up to 900C. Valves pressures range to 10.000 psi maximum pressure.

Corrosive Fluids 

For ANSI Class Valves, 150 to 600 for service Temperature Range to 1740F (-30 to 950C) a ceramic-lined ball valve is suitable for corrosive media with abrasive solids content at high temperatures. The valve can operate as a Stop Valve as well as a Throttling Control Valve. They can be equipped with a hand lever or actuators and valve accessories such as positioners, limit switches, and solenoid valves.

Extreme Temperatures

For a definition, temperature is a key factor for valve design. Generally, 425℃ is referred to as a high-temperature valve, but the most commonly used valve is the gate valve, globe valve, check valve, ball valve, and butterfly valve. High temp valves are used in petrochemical, chemical fertilizer, electric power, and metallurgy industries. Valve manufacturers divide high-temperature valves into five grades: 25~550℃ is grade PI, t>550~650℃ is grade PII, t>650~730℃ is grade PIII, t>730~816℃ is grade PIV, and t>816℃ is grade PV. 

Carbon Steel Materials 

When specifying Carbon Steel Valve bodies or trim, it is necessary to know the temperatures limits for continuous exposure. ASTM A216 covers three grades of carbon steel (Grades WCA, WCB, and WCC), the followings are their mechanical properties, chemical composition, and other properties. The maximum high temperature for these grades of steel is (800F).

Stainless Steel Materials

When specifying Stainless Steel Valve bodies or trim, it is necessary to know the temperatures limits for continuous exposure. Here are continuous temperature limits for grades of stainless steel: 

Grade 304

Continuous: 1,700°F (925°C)

Grade 316

Continuous: 1,700°F (925°C)

Grade 410

Continuous: 1,300°F (705°C)

Seat Design 

For Critical Services with high temperatures and pressures, Metal-Seats are recommended on bi-directional Valves, with graphite gaskets between the seats and valve body. 

Elastomeric Material

Elastomer performance becomes less predictable at the limits of its service temperature range. Elastomers become harder and less flexible and when the temperature elevates. At even lower temperatures they may crack. Changes in elastomer properties due to these temperatures undergo irreversible chemical changes. Service temperature can vary from elastomer to elastomer. The highest continuous service temperatures are silicone and fluorocarbon elastomers which can exceed 400°F (230°C)2, followed by polyacrylic and hydrogenated nitrile elastomers with a maximum service temperature between 320 and 350°F (160 – 180°C), whereas more ordinary elastomers such as Neoprene and Nitrile have a maximal operating temperature between 210 to 250°F (100 – 120°C).

Elastomer selection for valve seats is critical to the life of the valve.

Exotic Lining Material

To minimize corrosion in high temp applications, protective internal linings can be used for chemical resistance against direct exposure to acidic conditions at high temperatures.  To enhance service performance that allows for the coating to resist elevated temperatures, but at the same time remain flexible to sufficiently prevent the risk of cracking, a High-temperature epoxy coating for oil and gas production equipment such as separators, flare knock-out vessels, and evaporators operating under immersion is recommended for corrosion protection against a variety of chemicals in high-temperature equipment including boiler vessels, condensers, and heat exchangers.

Valve Trim Material

API Trim 17 is a universally accepted trim for extreme temperatures and corrosion. Combines good corrosion resistance with high-temperature resistance up to 800°C. This valve trim combines stainless steel materials: 347 and Hardfaced,  Stellite, Stelliteand 347.

How to order or Request High-Temperature Valves

The following details need to be provided:

Valve family (gate valve, globe valve, check valve, swing check valve, piston check valve, ball check valve, ball valve, butterfly valve, plug valve, safety relief valve)

Size 

• Valve rating/class (pressure classes 150, 300, 600, 800, 900, 1500, 2500, 4500) 
• Type of connection (flanged, threaded, butt weld with bore schedule) 
• Type of connection (flanged, threaded, butt weld, lug, and others)
• Service Media (oil, gas, water, steam, solids)
• Working temperature
• Working pressure
• Testing requirements and certifications
• Special Adders (for example Gear Actuator, Electric actuator, Pneumatic actuator)

FAQ’s