Two different routes to a pressure boundary
A forged-body purchase basis must identify the starting-material specification, forging process controls, required heat treatment, examination and valve design. Acceptance depends on the results required by those documents, not the word “forged” alone.
A cast-body purchase basis must identify the casting specification, required heat treatment, examination, repair controls and valve design. The supplied certificate and inspection record must correspond to the cast pressure-containing part.
| Selection point | Forged body | Cast body |
|---|---|---|
| Shape formation | Mechanically worked solid stock | Molten metal solidified in a mould |
| Geometry review | Check the offered machined body and drawing | Check the offered cast body and drawing |
| Manufacturing controls | Starting material, deformation, heat treatment, machining and examination | Moulding, solidification, heat treatment, repair controls, machining and examination |
| Examination plan | Matched to forging, machining and project risk | Matched to casting quality, repair history and project risk |
| Material identity | Forging specification and grade | Casting specification and grade |
Forging is not an automatic suitability certificate
The manufacturing route alone does not prove that one valve is stronger, safer or tighter than another. Acceptance depends on the material specification, mechanical properties, heat treatment, design, manufacture, examination and pressure testing required for the supplied valve.
Compare the actual forged and cast proposals against the same design conditions and project acceptance criteria. Product form is one line in that review, not a substitute for it.
Do not swap grade names by alloy family alone
ASTM A105 is a forging specification for carbon-steel piping components. A cast carbon-steel valve body is commonly described by a casting grade under a different specification. Likewise, ASTM A182 F316 is a forged stainless designation; a cast stainless designation is not the same certificate even where the nominal alloy family is similar.
A substitution review compares permitted chemistry, mechanical properties, heat treatment, pressure-temperature rating group, impact requirements, weld repair rules and corrosion requirements. The material certificate must match the actual product form supplied.
- Do not write “A105/WCB equivalent” as the full material requirement.
- Do not accept a cast grade on a forging certificate or a forging grade on a casting certificate.
- Check the governing code material group and rating table for the exact designation.
- State supplementary impact, hardness, PMI and corrosion requirements before manufacture.
Check the available size and construction
Product standards and manufacturer ranges do not assign one universal size at which a forged body must become a cast body. Check the offered valve family, pattern, material, pressure class and dimensions for the required NPS or DN.
If a project mandates the manufacturing route, keep that requirement visible in the material description and drawing review. A proposed change of route requires a documented comparison of material, design, dimensions, examination, testing and certificate scope.
How to review a proposed substitution
Require a completed deviation sheet. It should name the original and proposed material specifications, valve standard, pressure-temperature rating, dimensions, wall design, examination, test standard, repair history controls and certificate scope. General statements about “better material” are not sufficient.
For an installed replacement, compare face-to-face, end preparation, bore, operating envelope and actuator or handwheel clearance. The manufacturing route does not prove dimensional interchangeability.
Specification checks
- State the material specification, grade and product form for every pressure-containing part.
- Compare the applicable code rating group for each exact material designation.
- Set examination and weld-repair requirements to suit the manufacturing route and project risk.
- Request material certificates that identify heat, heat treatment and actual grade.
- Treat any change between forged and cast construction as a documented technical deviation.
Catalogue and RFQ
Standards publisher references
Published by Nordic Valves Ab Oy, the operator of FerraForge. These links describe the publishers’ official scope. Purchase documents must state the edition required by the project and include any amendments or owner specifications.
- ASTM A105/A105M - Carbon Steel Forgings for Piping ApplicationsASTM International · Official specification scope for forged carbon-steel piping components.
- ASTM A182/A182M - Forged or Rolled Alloy and Stainless Steel Piping ComponentsASTM International · Official specification scope for forged alloy- and stainless-steel piping components.
- ASME B16.34 - Valves - Flanged, Threaded, and Welding EndASME · Official scope covering valve pressure-temperature ratings, materials, dimensions, testing and marking.