Overview
In an ASTM A105 vs ASME SA-105 inquiry, both designations relate to carbon steel forgings used for pressure-system piping components, but the governing publication and code context are different. ASTM publishes A105/A105M. ASME includes SA-105/SA-105M in BPVC Section II, Part A for ASME Code use.
A purchase order should use the designation and edition required by the governing code and contract. Do not change A105 to SA-105, or the reverse, only because the material names look similar.
Why It Matters for Pipe Components
Material designation affects certification, code acceptance, test requirements, purchaser options, and document review. The active ASTM A105/A105M scope includes forged carbon steel flanges, fittings, valves, and similar pressure-system components for ambient and higher-temperature service. The material specification does not define the flange dimensions.
A flange described as “A105 Class 150” still needs a dimensional standard such as the applicable ASME B16 document, plus size, type, facing, and bore. Material compliance and dimensional compliance are separate checks.
Edition alignment matters. ASTM and ASME publication cycles do not always use the same year. A code project may require the SA specification adopted by the selected ASME BPVC edition. A non-code piping project may specify ASTM A105/A105M directly.
Methods, Parameters, or Process
Separate the decision into material, dimensions, and code context.
| Question | ASTM A105/A105M | ASME SA-105/SA-105M |
|---|---|---|
| Publisher | ASTM International | ASME within BPVC Section II, Part A |
| Main use | Material specification for covered forged piping components | ASME-adopted material specification for applicable Code work |
| Dimensions | Not the primary flange dimensional standard | Not the primary flange dimensional standard |
| Purchase control | ASTM edition named by the order | ASME BPVC edition and adopted specification named by the order |
| Certification | MTR should identify the ordered specification and edition | MTR and Code documentation should identify the required SA designation |
| Interchangeability | Requires contract and code review | Requires contract and code review |
The ASTM scope identifies forgings for flanges, fittings, valves, and similar parts, ordered either to purchaser dimensions or referenced dimensional standards. It also provides supplementary requirements that apply when the purchaser specifies them. Therefore, a buyer should list any extra testing, inspection, hardness, impact, NDE, or certification requirement explicitly.
Do not use A105 or SA-105 as a generic label for plate. These are forging specifications. If a supplier proposes plate for a blind or custom flange, the product form, plate material specification, dimensional standard, and project approval must be addressed separately.
For low-temperature service, do not assume A105 or SA-105 is acceptable based on carbon steel chemistry alone. The design code, minimum design metal temperature, impact-test rules, material toughness, thickness, and project specification must be reviewed.
Verification required: exact technical differences between a particular ASTM A105/A105M edition and the SA-105/SA-105M text adopted by a particular ASME BPVC edition must be checked in the licensed documents.
Supplier and Inspection Checklist
- Confirm whether the project requires ASTM A105/A105M or ASME SA-105/SA-105M.
- Record the contract-required edition.
- Verify the component is supplied in an allowed product form.
- Check heat number traceability from forging to finished flange.
- Review chemistry, tensile, yield, elongation, hardness, heat treatment, and required tests against the ordered edition.
- State supplementary requirements individually when needed.
- Confirm the separate flange dimensional standard, size, class, type, facing, and bore.
- Review repairs, weld repair restrictions, and purchaser approval requirements.
- Ensure the MTR uses the designation required by the purchase order.
- Do not accept a certificate that silently changes ASTM and ASME designations.
Application to Pipe Fittings, Valves, and Flanges
A105 and SA-105 designations appear on weld neck, slip-on, blind, socket weld, threaded, and other forged carbon steel piping components. They may also appear on valve bodies, fittings, and similar parts within the specification scope.
For pressure-vessel nozzle flanges or ASME Code equipment, the SA designation may be required by the construction code and material tables. For general process piping, the project may specify ASTM material standards. The design authority should make that decision before quotation.
FAQ
Are ASTM A105 and ASME SA-105 identical?
They are closely related specification designations, but contractual equivalence should not be assumed across publishers and editions. Check the adopted ASME text and project requirements.
Does A105 define Class 150 flange dimensions?
No. A105/A105M is a material specification. The flange dimensional standard defines dimensions and rating information.
Can A105 be used for a plate flange?
A105/A105M is a forging specification. A plate-made component needs an applicable plate specification and engineering approval.
Is A105 suitable for every low-temperature service?
No. Minimum temperature, thickness, toughness, impact-test rules, code requirements, and project specifications must be reviewed.
What should appear on the MTR?
The ordered material designation and edition, heat identification, chemical and mechanical results, heat-treatment information, and any required supplementary-test results should be traceable.
Next Steps
Write material and dimensions as separate lines in the RFQ. State ASTM A105/A105M or ASME SA-105/SA-105M with the required edition, then state the flange standard, size, class, type, facing, bore, tests, and certificate requirements.
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