ASTM A352 LCB vs LCC: Which Low-Temperature Valve Body Grade Should You Specify?
On this page
ASTM A352 LCC is not simply a “colder” version of LCB. Both grades have the same usual minimum Charpy impact-test temperature of -46°C (-50°F) under ASTM A352/A352M-21. LCC has higher minimum tensile strength, yield strength, and impact-energy acceptance, while LCB has slightly higher minimum elongation.
Specify the grade required by the valve design, ASME pressure-temperature rating, and project specification. LCC may be preferable when higher strength is needed, but it should not replace LCB without review.
These are material values, not complete-valve ratings. ASTM chemistry notes, heat treatment, casting size, design code, and project requirements still apply.
The -46°C value is a material test temperature, not permission to operate every finished valve there. Minimum design metal temperature must include normal operation, ambient exposure, start-up, shutdown, depressurization, and credible transients. Body qualification cannot override limits in bolting, trim, seats, packing, gaskets, seals, or accessories.
If the design condition is below -46°C, changing from LCB to LCC does not solve the problem. The project may need another ASTM A352 grade, a suitable austenitic stainless steel, or a nickel alloy after a code and service review.
LCC may be the clearer choice when:
- The project material specification names LCC.
- The valve design and pressure-temperature rating are based on LCC.
- The purchaser requires its higher Charpy acceptance.
- Standardizing on LCC reduces material variation across an approved project range.
LCB remains valid when the project permits it, its properties satisfy the design, and the casting meets impact, heat-treatment, NDE, and documentation requirements. A lower grade code does not mean unsuitable material.
Before accepting LCC against an LCB order, confirm:
1. The governing valve and piping codes permit the change.
2. The selected pressure-temperature rating is recalculated or verified.
3. Welding procedures and repair-welding qualifications cover the offered grade.
4. Impact-test temperature and actual Charpy results meet the project requirement.
5. The client or EPC approves the material deviation in writing.
6. Nameplates, drawings, material certificates, and traceability records are revised.
Dual certification should also be based on one heat meeting all requirements of both grades, supported by the material test report. It should never be inferred from a supplier’s statement that the chemistries are “close.”
Request the material test report with heat number, actual chemistry, heat treatment, tensile results, Charpy test temperature, individual and average impact values, and any repair-weld records. The casting markings and certificate heat number should match the delivered pressure parts.
Do not default to LCC. Use LCB when the approved design and project specification call for it; use LCC when its higher strength or impact acceptance belongs in the design basis. In either case, test records and complete-valve temperature review matter more than the final letter.
Specify the grade required by the valve design, ASME pressure-temperature rating, and project specification. LCC may be preferable when higher strength is needed, but it should not replace LCB without review.
LCB and LCC at a Glance
| ASTM A352 requirement | LCB | LCC | Selection meaning |
| Usual minimum impact-test temperature | -46°C (-50°F) | -46°C (-50°F) | LCC is not qualified to a lower usual temperature |
| Tensile strength | 450–620 MPa | 485–655 MPa | LCC has a higher strength range |
| Minimum yield strength | 240 MPa | 275 MPa | LCC may support a higher applicable pressure-temperature rating |
| Minimum elongation in 50 mm | 24% | 22% | LCB has slightly higher specified elongation |
| Minimum average Charpy energy | 18J | 20J | LCC has a modestly higher impact acceptance |
| Maximum carbon in the main composition table | 0.30% | 0.25% | LCC starts with a lower maximum carbon limit |
| Maximum manganese in the main composition table | 1.00% | 1.20% | LCC permits more manganese in the basic limit |
These are material values, not complete-valve ratings. ASTM chemistry notes, heat treatment, casting size, design code, and project requirements still apply.
The Temperature Limit Does Not Separate the Two Grades
The most common selection error is to assume that LCC is suitable for a lower temperature because it has higher strength. ASTM A352 lists -46°C as the usual minimum impact-test temperature for both grades. LCC therefore improves specified strength and impact acceptance, not the nominal low-temperature test point.The -46°C value is a material test temperature, not permission to operate every finished valve there. Minimum design metal temperature must include normal operation, ambient exposure, start-up, shutdown, depressurization, and credible transients. Body qualification cannot override limits in bolting, trim, seats, packing, gaskets, seals, or accessories.
If the design condition is below -46°C, changing from LCB to LCC does not solve the problem. The project may need another ASTM A352 grade, a suitable austenitic stainless steel, or a nickel alloy after a code and service review.
When Does LCC Make More Sense?
LCC is the stronger grade. This can matter when the applicable ASME B16.34 material group and pressure-temperature table are used. It does not mean every LCC valve has a higher allowable pressure; class, size, wall thickness, construction, temperature, and standard edition still control.LCC may be the clearer choice when:
- The project material specification names LCC.
- The valve design and pressure-temperature rating are based on LCC.
- The purchaser requires its higher Charpy acceptance.
- Standardizing on LCC reduces material variation across an approved project range.
LCB remains valid when the project permits it, its properties satisfy the design, and the casting meets impact, heat-treatment, NDE, and documentation requirements. A lower grade code does not mean unsuitable material.
Is LCC an Automatic Substitute for LCB?
No. LCC may look like an upgrade, but substitution is a design and procurement change. The grades have different chemistry limits, mechanical requirements, UNS designations, and ASME material-group treatment. Datasheets, drawings, material lists, welding documents, and orders must remain consistent.Before accepting LCC against an LCB order, confirm:
1. The governing valve and piping codes permit the change.
2. The selected pressure-temperature rating is recalculated or verified.
3. Welding procedures and repair-welding qualifications cover the offered grade.
4. Impact-test temperature and actual Charpy results meet the project requirement.
5. The client or EPC approves the material deviation in writing.
6. Nameplates, drawings, material certificates, and traceability records are revised.
Dual certification should also be based on one heat meeting all requirements of both grades, supported by the material test report. It should never be inferred from a supplier’s statement that the chemistries are “close.”
What Should the RFQ Require?
Write more than “ASTM A352 low-temperature carbon steel.” State the grade and ASTM edition, design code, pressure class, design temperatures, body and bonnet materials, trim, bolting, seats, seals, impact testing, NDE, pressure testing, and documents.Request the material test report with heat number, actual chemistry, heat treatment, tensile results, Charpy test temperature, individual and average impact values, and any repair-weld records. The casting markings and certificate heat number should match the delivered pressure parts.
Do not default to LCC. Use LCB when the approved design and project specification call for it; use LCC when its higher strength or impact acceptance belongs in the design basis. In either case, test records and complete-valve temperature review matter more than the final letter.
