The temperature rating of American standard gate valves (following ASME, API and other standards) is closely related to material properties and medium characteristics, and different temperature ranges correspond to specific material selection and application scenarios. The following are classified into four temperature levels: low temperature, normal temperature, medium temperature, and high temperature, with detailed explanations based on materials and industry scenarios:
1、 Low temperature level (-254 ℃ ≤ T ≤ -46 ℃)
Applicable materials
Ultra low temperature materials: austenitic stainless steel (304L, 316L, -196 ℃~200 ℃), nickel based alloy (Inconel, -254 ℃~650 ℃), low temperature steel (LC3/LCA, LC4/LCB, in compliance with API 607 low temperature requirements)- 101 ℃~343 ℃).
Sealing surface: Soft seal (PTFE, -200 ℃~260 ℃) or metal hard seal (Stellite overlay, resistant to low temperature impact).
Application scenarios
Liquefied natural gas (LNG) industry chain:
Low temperature Gate valves for LNG receiving stations and transport ships (medium temperature -162 ℃) used in loading, unloading, and storage systems (required to pass API 624 fire resistance test and low temperature impact test).
Cryogenic chemical plant:
Air separation equipment (liquid nitrogen, liquid oxygen, -196 ℃) and ethylene cracking low-temperature separation unit require valves to be resistant to low-temperature brittle fracture and sealing surfaces to be leak free (to avoid flammable gas spillage).
Polar conditions:
Arctic oil and gas extraction and polar pipelines require materials to pass a -46 ℃ low-temperature impact test (such as API 6A wellhead equipment valves).
2、 Normal to medium temperature range (-46 ℃<T ≤ 425 ℃)
Applicable materials
Room temperature materials: carbon steel (A105, WCB, -29 ℃~425 ℃), low-alloy steel (WC6/WC9150 ℃~593 ℃, requiring heat treatment).
Corrosion resistant materials: 316 stainless steel (-29 ℃~650 ℃, acid and alkali resistance at room temperature), duplex steel (2205, -50 ℃~300 ℃, chloride ion corrosion resistance).
Application scenarios
Petrochemical pipelines:
Atmospheric and vacuum distillation unit (medium temperature 300 ℃~350 ℃, crude oil/heavy oil), using A105 carbon steel gate valve, Class 300 grade, capable of withstanding medium and high pressure (10~25MPa).
Acidic gas fields (including H ₂ S, requiring NACE MR0175 certification) use 316L stainless steel valves to prevent stress corrosion cracking.
Power industry:
The steam water system of the thermal power plant (steam temperature 350 ℃~400 ℃, pressure 10~16MPa), with WCB carbon steel gate valve used for the main steam pipeline, requires ASME BPVC Section III strength certification.
Municipal and industrial water systems:
Drinking water and circulating water pipelines (at room temperature~80 ℃), Class 150 cast iron or stainless steel gate valves, low-pressure scenarios (≤ 2.0MPa), with emphasis on sealing surface anti-corrosion (such as epoxy resin coating).
3、 High temperature level (425 ℃<T ≤ 650 ℃)
Applicable materials
High temperature alloys: Cr Mo steel (P11, P22450 ℃~593 ℃), austenitic stainless steel (310S, 600 ℃~700 ℃), nickel based alloys (Inconel 625650 ℃ or above).
Sealing surface: Welding cobalt based alloy (Stellite 6, resistant to high temperature wear at 650 ℃) or nickel based alloy (hardness ≥ HRC45).
Application scenarios
Refining and chemical high-temperature equipment:
Catalytic cracking unit (regenerated flue gas temperature 600 ℃~650 ℃), using P22 steel gate valve, Class 600 grade, needs to withstand high temperature creep and oxidation (surface aluminum treatment enhances oxidation resistance).
The inlet of the hydrocracking reactor (hydrogen+oil and gas, 500 ℃~550 ℃, pressure 15~25MPa) adopts forged A182 F91 alloy steel valve, which meets the high temperature and high pressure requirements of API 6A.
Metallurgy and Glass Industry:
The blast furnace hot air duct (hot air temperature 550 ℃~600 ℃) uses 310S stainless steel gate valves, which are resistant to high temperature oxidation and sulfur corrosion, and the sealing surface needs to be wear-resistant (washed away by dust particles).
In the field of new energy:
Thermal power generation molten salt system (molten salt temperature 565 ℃), Inconel 625 alloy gate valve, to prevent molten salt crystallization blockage and high-temperature corrosion, requiring low leakage rate (bubble level sealing).
4、 Special temperature conditions and selection points
1. Temperature pressure matching principle
High temperature pressure reduction: For Class 300 A105 carbon steel valves, the allowable pressure can be reduced from 5.1MPa at room temperature to 4.1MPa at 425 ℃ (refer to ASME B16.34 material list), and overpressure operation should be avoided.
Low temperature toughening: Materials with impact toughness ≥ 27J (such as LC3 low-temperature steel) must be selected below -46 ℃, and ordinary carbon steel (which is prone to brittle fracture) is prohibited from use.
2. Compliance with industry standards
Petroleum industry: Follow API 6D (temperature grade PR2, -29 ℃~121 ℃) or API 600 (high temperature gate valve, ≤ 427 ℃).
Power industry: It is required to comply with ASME BPVC Section VIII Div. 1, and high-temperature valves need to undergo aging treatment (to eliminate internal stress).
3. Key points of sealing surface maintenance
Regularly check the wear of the sealing surface at high temperatures (such as Stellite weld layer cracks), and prevent the sealing grease from solidifying at low temperatures (using low-temperature lubricating grease that does not harden at -196 ℃).
Selection suggestion: Based on the temperature, pressure, and corrosiveness of the medium, priority should be given to consulting the ASME B16.34 material allowable stress table, combined with industry standards such as API 600/6D, while considering the compatibility between the sealing surface material and temperature (such as soft seals not exceeding 260 ℃, and hard seals requiring evaluation of bonding accuracy at high temperatures).
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