A216 WCB vs WCC

Quick Answer

WCB and WCC are both ASTM A216 cast carbon steel grades for high-temperature service. WCC has higher tensile strength (485-655 MPa vs 485-655 MPa), higher yield (275 MPa vs 250 MPa), and mandatory impact testing at -29°C. Specify WCC when the design requires better low-temperature toughness or higher allowable stress. WCB remains the default for most standard-service valve bodies.

Side-by-Side Comparison

Both grades fall under ASTM A216, which covers weldable carbon steel castings for valves, flanges, fittings, and other pressure-containing parts. The differences are subtle but meaningful for design engineers and procurement teams.

Property	WCB	WCC
Carbon	0.30% max	0.25% max
Manganese	1.00% max	1.20% max
Silicon	0.60% max	0.60% max
Tensile strength	485-655 MPa (70-95 ksi)	485-655 MPa (70-95 ksi)
Yield strength (min)	250 MPa (36 ksi)	275 MPa (40 ksi)
Elongation (min)	22%	22%
Reduction of area (min)	35%	35%
Impact test	Not required (unless specified)	Required at -29°C per ASTM A216
MDMT	-29°C (-20°F)	-29°C (-20°F)
Max service temp	425°C (800°F)	425°C (800°F)

Key Differences Explained

Chemistry: WCC limits carbon to 0.25% (vs 0.30% for WCB) but allows higher manganese (1.20% vs 1.00%). Lower carbon improves weldability and toughness. Higher manganese compensates for strength while refining the grain structure.

Yield strength: WCC’s minimum yield of 275 MPa (40 ksi) exceeds WCB’s 250 MPa (36 ksi) by 10%. This directly affects the allowable stress values used in pressure design calculations per ASME B31.3 and ASME Section VIII.

Impact toughness: The most practical difference. WCC mandates Charpy V-notch impact testing at -29°C. WCB does not require impact testing unless supplementary requirement S4 is invoked. Projects with minimum design metal temperatures (MDMT) approaching -29°C often specify WCC to avoid the cost of supplementary impact testing on WCB.

When to Specify WCB vs WCC

Use WCB for general-purpose valve bodies and fittings in standard refinery, petrochemical, and power plant service between -29°C and 425°C. It is the default cast carbon steel for gate, globe, and check valves in ASME Class 150 through 2500.

Use WCC when:

• Project specs require guaranteed impact toughness at or near -29°C
• Higher allowable stress reduces valve body wall thickness or weight
• The piping specification calls for WCC explicitly (common in LNG and cryogenic-adjacent systems)

Both grades pair with ASTM A105 forged flanges and carbon steel pipes. For temperatures below -29°C, switch to ASTM A352 LCB. For sour service, both must meet NACE MR0175 hardness requirements (22 HRC max).

The casting process is identical for both grades. The foundry controls chemistry and heat treatment to meet whichever grade the purchase order specifies. WCC castings cost marginally more due to impact testing requirements and tighter chemistry control. Both grades require mill test certificates per EN 10204 3.1 documenting chemistry, mechanicals, and heat treatment. Hydrostatic testing and non-destructive examination follow the applicable valve or fitting standard.

Read the full guide to valve materials