View Inconel 625 Flanges

Buyers often write only “ASTM B564 UNS N06625 flange.” That identifies the material route, but it does not fully define the required item. Grade 1 versus Grade 2 affects heat-treatment condition and intended temperature regime, while ASME B16.5 or another dimensional standard controls a different part of the order.

What ASTM B564 Covers

ASTM B564 is a material specification for nickel-alloy forgings. For UNS N06625, it sets requirements associated with chemistry, heat treatment, mechanical properties and testing. It does not, by itself, define every flange dimension or pressure-temperature rating.

ASTM B564 Grade 1 vs Grade 2

The 1100°F boundary is not permission to select a flange from temperature alone. Design pressure, applicable code rules, corrosion environment, fabrication history, mating components and project-specific acceptance criteria still need review. Hot working or subsequent reannealing can also affect properties, so the delivered condition and traceability matter.

ASTM B564 vs ASME B16.5

ASTM B564 and ASME B16.5 are complementary, not competing specifications. A usable order may identify ASTM B564 UNS N06625 Grade 1 or Grade 2 for the forged material, then ASME B16.5 for the applicable flange size, class, dimensions, tolerances, marking and testing framework.

“Alloy 625 flange” is therefore incomplete. Buyers should add flange type, NPS or DN, class or PN, facing, bore or matching pipe schedule, dimensional standard and edition. Pressure class is not a material grade, and Grade 1 or Grade 2 is not a pressure rating.

What to Check on the MTC

The MTC should be checked against the purchase order and the adopted specification edition. At minimum, review:

1. Material identity: ASTM B564, UNS N06625 and the ordered Grade 1 or Grade 2 condition.
2. Traceability: heat or lot reference connected to the flange marking and item documentation.
3. Heat treatment: the reported condition and any required temperature record or statement.
4. Chemistry and mechanical results: actual reported values assessed against the governing edition and purchase order.
5. Required tests: only the examinations, supplementary requirements and acceptance criteria actually invoked by the order.
6. Certification scope: document type, manufacturer identity, inspector or third-party endorsement when contractually required.

Producer datasheets are useful for typical alloy behaviour, but typical values are not acceptance limits for a purchase order. Acceptance should follow the cited material specification, dimensional standard and project requirements.

RFQ Checklist for UNS N06625 Flanges

Frequently Asked Questions

Is ASTM B564 the same as Inconel 625?

No. ASTM B564 is a product/material specification. UNS N06625 is the alloy designation commonly associated with Alloy 625; Inconel is a trademark. A controlled order should cite the applicable specification, UNS number, grade or condition and product details.

Does ASTM B564 define flange pressure class?

No. Grade 1 and Grade 2 describe material conditions. Pressure class belongs to the applicable flange standard and must be evaluated with temperature, material grouping and code requirements.

Can Grade 2 replace Grade 1?

Not automatically. Even if Grade 2 is solution annealed, substitution can affect the approved specification, design review, documentation and commercial scope. Obtain formal approval first.

Which standard applies to Alloy 625 flanges?

ASTM B564 is commonly used for UNS N06625 forged flange material. The flange also needs an applicable dimensional standard such as ASME B16.5, or another project-specified standard for its size and type.

Primary References

• ASTM B564-25 specification page — scope and Grade 1/Grade 2 service notes.
• ASME B16.5-2025 overview — flange ratings, dimensions, tolerances, marking and testing scope.
• Special Metals INCONEL alloy 625 bulletin — typical alloy data; not a substitute for specification acceptance limits.