Quick Answer：
WCB is the most commonly specified grade of cast carbon steel used in industrial ball valves, comprising the vast majority of oil/gas, steam, power, and general-purpose applications in a temperature range of – 29 degrees centigrade to 425 degrees centigrade. The grade can accommodate pressures from 150 LB to 2500 LB as per ASME B16.34 and serves as an economical alternative to alloy steels in any application that falls within those specifications. ONERO produces WCB ball valves at our casting plant with 3,000-ton capacity, equipped with a hydro test on each valve, API 6D, API 607, ISO 15848, ranging in size from ½” to 48”.
What Is WCB (ASTM A216 Cast Carbon Steel)?
ASTM A216 is the ASME standard for cast carbon steel suitable for high-temperature applications. WCB (Weldable Cast B), which stands for Weldable Cast Body, is the most common grade among three types of ASTM A216. The other two types are WCA and WCC, which represent lower and higher strength grades, respectively.
The minimum tensile strength of ASTM A216 WCB valve body is 485 MPa, and the minimum yield strength is 250 MPa. Carbon steel WCB has a maximum carbon content of 0.30%, 0.60% silicon, and 1.00% manganese. This helps to achieve sufficient weldability without necessitating post-weld heat treatment in most cases.
The carbon steel WCB ball valve body is made using the sand casting process, which allows intricate casting for larger valve bodies that cannot be forged economically.
ASME B16.34 Pressure-Temperature Rating Table
ASME B16.34 standard dictates the pressure-temperature ratings of valves made from material group 1.1, which includes A216 WCB. The pressure-temperature ratings for WCB ball valves decrease with an increase.
| Pressure Class | Rating at 38°C (100°F) | Rating at 260°C (500°F) | Rating at 425°C (800°F) |
|---|---|---|---|
| Class 150 | 19.6 bar (285 psi) | 13.8 bar (200 psi) | 12.1 bar (175 psi) |
| Class 300 | 51.1 bar (740 psi) | 44.8 bar (650 psi) | 39.0 bar (566 psi) |
| Class 600 | 102.1 bar (1480 psi) | 89.6 bar (1300 psi) | 77.9 bar (1130 psi) |
| Class 900 | 153.2 bar (2220 psi) | 134.4 bar (1950 psi) | 116.9 bar (1695 psi) |
| Class 1500 | 255.3 bar (3705 psi) | 224.1 bar (3250 psi) | 195.1 bar (2830 psi) |
| Class 2500 | 425.5 bar (6170 psi) | 373.4 bar (5415 psi) | 325.1 bar (4715 psi) |
WCB ball valve pressure temperature ratings require that the buyer verify the true operating temperature when determining the pressure rating rather than using the design pressure at ambient conditions. The Class 300 valve operating at 425 degrees centigrade works at much lower allowable pressure compared to the ambient.
What Is Its Low-Temperature Limit?
WCB Standard Floor: -29 Degrees Celsius
The ASTM A216 WCB grade of cast iron has a standard minimum service temperature rating of -29 degrees Celsius or -20 degrees Fahrenheit. Anything colder than this minimum will not have guaranteed impact toughness.
Construction projects in cold regions, LNG satellites, or any other cryogenic-adjacent service that demands a lower minimum temperature requirement should use a different material.
LCB (ASTM A352 Grade LCB) increases the minimum temperature to -46 degrees Celsius. LCC increases it to -73 degrees Celsius. Below -73 degrees Celsius, austenitic stainless steel or nickel alloy castings are used.
Impact Test Verification
In situations where low-temperature performance is needed around the WCB floor, ONERO carries out Charpy V-notch impact tests at the minimum design temperature. This is contained within the material documentation package and helps verify toughness of the casting lot based on the results of the test and not just the chemistry compliance.
What Is Its High-Temperature Limit?
The practical upper temperature ceiling for ASTM A216 WCB is 425 degrees Celsius. Above this temperature, graphitization of the carbon steel microstructure becomes a concern, progressively reducing the material’s creep resistance and toughness. This is not a sudden failure mode but a long-term degradation that compromises valve integrity over the design life.
For service above 425 degrees Celsius, WC6 (chromium-molybdenum steel per ASTM A217) extends the ceiling to approximately 595 degrees Celsius. WC9 covers similar temperature ranges with a different alloy composition. Beyond WC6 and WC9, austenitic stainless or nickel-based alloys are required.
WCB vs Forged A105: Which to Choose?
ASTM A105 is the forged carbon steel equivalent used for smaller-bore and flanged valve bodies. The ASTM A216 WCB valve body is cast; A105 is forged. Both cover similar temperature and pressure ranges under ASME B16.34 Group 1.1.
The selection logic follows size and complexity. Forged A105 suits valve bodies below DN100 (4 inch) where forging is economical and produces a denser, more uniform grain structure. Cast WCB suits larger valve bodies where the size and geometry complexity make forging impractical or uneconomical. Above DN100, WCB is the standard specification for most carbon steel ball valve applications.
Mechanical properties are comparable between the two. A105 has slightly higher minimum tensile strength at 485 MPa versus WCB’s 485 MPa, with A105 yield strength at 250 MPa and WCB at 250 MPa, effectively equivalent. The choice is manufacturing method and economy, not mechanical performance.
Typical Applications
Steam distribution, crude oil pipeline isolation, produced water handling, power plant auxiliary systems, and general hydrocarbon processing are the core applications for WCB ball valves. Service is limited to non-corrosive or mildly corrosive media within the temperature range. For acid, chloride, or high-humidity environments, stainless steel grades replace WCB.
ONERO has supplied WCB ball valves to power station auxiliary steam systems in Southeast Asia requiring Class 600 ratings at continuous service temperatures of 380 degrees Celsius, and to crude oil pipeline projects in the Middle East requiring Class 300 to Class 900 valves across a 400-unit project order.
Why Specify ONERO WCB Ball Valves?
ONERO’s WCB casting operation uses a 3,000-tonne capacity facility with full casting process control from pattern to finished body. Every carbon steel WCB ball valve body undergoes radiographic or ultrasonic examination per applicable standards before machining.
Simple floating design for tight sealing. Cost-effective, low-torque. 2″–42″, Class 150-2500LB.
View ProductHydrostatic pressure testing is conducted on every finished unit, not on a sample basis. Documentation includes material test reports with chemical and mechanical properties, casting examination records, and pressure test certificates.
ONERO’s quality holds API 607 certification for WCB ball valves, with NACE MR0175 compliance available for carbon steel where sour service is specified. The full size range from 1/2 inch to 48 inches and Class 150 through Class 2500 is available with standard lead times of 4 to 6 weeks for stock configurations. Contact our technical team today.
