Which Valve is used for High Temperature?
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.
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 a 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.
High Temperature Ball Valve
Design Temperature from 121° to 200°C (249,8° to 392°F)
Ball valves for this temperature range can have soft seated construction with thermoplastic inserts (Devlon V, Nylon, RPTFE, PEEK) and elastomer seals O-ring (FKM, FFKM, HNBR, EPDM, FEPM); material construction does not require any particular care: carbon steel and stainless steel bodies and closures are acceptable, if suitable to other service conditions and pressure ratings. To prevent galling of the substrate the PMSS (Primary Metal Secondary Soft) is a possible construction provided by ENP or metal seated coating on the ball to maintain a differential hardness between the ball itself and the seat ring.
Design Temperature from 201° to 350°C (393,8° to 662°F)
Ball valves for this temperature range should have metal seated construction with Tungsten or Chrome Carbide coating (from 150µm to 400µm) on the ball and seat sealing surfaces with graphite packing and suitable stem extension; the use of thermoplastic and elastomer compounds like PEEK and FFKM should be limited to a temperature below 250°C and low pressures; carbon steel and stainless steel materials, specific for high-temperature conditions, should be selected for pressure containing and controlling parts; materials with good strength properties like 17-4PH, XM19 or in some cases Inconel 625 and 718 for the ball, seat rings, and stem, are recommended in case of combination with other service conditions like high pressure and corrosive & dirty applications.
Design Temperature from 351° to 550°C (663,8° to 1022°F)
Ball valves for this temperature range must have metal seated construction with Chrome Carbide coating (from 150µm to 400µm) or Stellite coating on the ball and seats sealing surfaces with graphite packing and suitable stem extension; the difference between the hardness of the seat and the ball is necessary to avoid galling; stainless steel (specific for high-temperature conditions) for body and closures and Inconel 625 or Inconel 718 as trim or at least as stem material are strictly recommended for suitable valve construction.
Design Temperature from 551° to 1100°C (1023,8° to 2012°F)
Ball valves for this extreme temperature range must have metal seated special construction with Stellite coating, graphite packing, and suitable stem extension; specific alloys for high-temperature conditions must be selected for suitable valve construction.
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