Many enquiries for special alloys start with a grade name – “Hastelloy C276”, “Inconel 625”, “Duplex 2507” – copied from a previous job. If the service conditions have changed, that grade may be more than you need, or not enough. Sharing the service environment lets the supplier flag questions before you commit.
Service Data Worth Sharing
- Process fluid and contaminants: acids, chlorides, H₂S, caustic, oxidisers and their concentrations.
- Temperature range: normal, maximum and minimum, including upsets and cleaning cycles.
- Pressure and pressure class of the line.
- pH and oxygen conditions where relevant.
- Sour service requirements such as NACE MR0175 / ISO 15156.
- Existing materials in the system and any history of corrosion or failure.
- Design code and any client material specification.
Then State the Grade and Form
Once the service is described, state the grade you have selected, the UNS number, the product standard for each form (for example ASTM B366 for nickel-alloy fittings, B564 for forgings, A182 for duplex forgings) and any supplementary requirements. The supplier can then confirm availability or raise questions about suitability.
Why This Matters
Special alloys are costly and often have long lead times. A short description of the service can prevent over-specifying – or, more importantly, under-specifying – and helps confirm that every form (pipe, fittings, flanges, fasteners) is available in the same alloy. Final material selection remains the responsibility of your engineering team.
Related: documenting a material substitution.
Frequently Asked Questions
Why should I describe the service conditions in an alloy enquiry?
So the supplier can check whether the requested grade and forms are consistent with the service and raise questions before you commit to an expensive, long-lead material.
Does the supplier choose the alloy for me?
No. Material selection is the responsibility of your engineering team; service data simply allows informed questions and confirmation of availability.
Which standards cover nickel-alloy fittings and forgings?
Nickel-alloy buttweld fittings are commonly ordered to ASTM B366 and forgings to ASTM B564, with grade identified by UNS number.
