WCB vs LCB vs WCC: Cast Carbon Grades
WCB, LCB, and WCC are the three most common cast carbon steel grades used for valve bodies, pump casings, and specialty fittings in the piping industry. All three are covered by ASTM A216 (WCB, WCC) and ASTM A352 (LCB). The key difference is temperature capability: WCB is the standard ambient/elevated-temperature grade, LCB is designed for low-temperature service, and WCC provides higher strength at ambient and moderate temperatures.
Quick Answer
WCB (ASTM A216) is the default cast carbon steel for valve bodies in standard temperature service (-29°C to 425°C). LCB (ASTM A352) is the low-temperature version, impact tested at -46°C, for cryogenic and cold service. WCC (ASTM A216) has higher tensile and yield strength than WCB and is used for higher-pressure classes or where improved mechanical properties are required.
Specifications and Properties
| Property | WCB (A216) | WCC (A216) | LCB (A352) |
|---|---|---|---|
| Specification | ASTM A216 | ASTM A216 | ASTM A352 |
| Service | Standard temperature | Standard (higher strength) | Low temperature |
| Min design temp | -29°C (-20°F) | -29°C (-20°F) | -46°C (-50°F) |
| Max design temp | 425°C (800°F) | 425°C (800°F) | 345°C (650°F) |
| Carbon (max) | 0.30% | 0.25% | 0.30% |
| Manganese (max) | 1.00% | 1.20% | 1.00% |
| Silicon (max) | 0.60% | 0.60% | 0.60% |
| Tensile strength (min) | 485 MPa (70 ksi) | 485 MPa (70 ksi) | 450 MPa (65 ksi) |
| Yield strength (min) | 250 MPa (36 ksi) | 275 MPa (40 ksi) | 240 MPa (35 ksi) |
| Elongation (min) | 22% | 22% | 24% |
| Reduction of area (min) | 35% | 35% | 35% |
| Impact test | Not mandatory | Not mandatory | Mandatory at -46°C |
| Impact energy (min) | - | - | 18 J (13 ft-lbs) avg |
| Heat treatment | Normalize, N+T, or QT | Normalize, N+T, or QT | Normalize + temper or QT |
| Matching wrought pipe | A106 Gr.B | A106 Gr.C | A333 Gr.6 |
| Matching forging | A105 | A105 | A350 LF2 |
| Relative cost | Baseline | 5-10% premium | 15-25% premium |
Comparison: Application Scenarios
| Service Condition | Recommended Grade |
|---|---|
| General process (ambient to 425°C) | WCB |
| High-pressure class (1500/2500) | WCC |
| Low-temperature (-29 to -46°C) | LCB |
| Arctic pipeline valves | LCB |
| LNG service (below -46°C) | LCC (A352) or stainless |
| Fire water / utility | WCB |
WCB: The Standard
WCB is the workhorse cast carbon steel, equivalent to wrought A105 forgings and A106 Gr.B pipe. It is the default body material for gate, globe, check, and ball valves in ASME Class 150 through 2500 ratings at standard temperatures. It accounts for the majority of carbon steel valve production worldwide.
LCB: Low-Temperature Service
LCB requires mandatory Charpy V-notch impact testing at -46°C to guarantee ductile behavior at low temperatures. The normalized or quenched-and-tempered heat treatment refines the grain structure to achieve this toughness. LCB is specified for cold climate installations, refrigeration systems, depressurization scenarios, and any piping where the minimum design metal temperature (MDMT) falls below WCB’s exemption limit.
WCC: Higher Strength
WCC has a higher minimum yield strength (275 MPa vs. 250 MPa) and lower carbon content (0.25% vs. 0.30%) with higher manganese (1.20% vs. 1.00%). The higher yield is advantageous for high-pressure valve classes where allowable stress governs wall thickness. The lower carbon improves weldability for valves requiring field weld repairs or weld-end configurations.
For details on cast vs. forged steel production and how it affects valve quality, refer to the dedicated guide.
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