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A nickel alloy enquiry arrives in trade names. A client asks for Inconel 625 butt weld fittings, 904L flanges or C-276 elbows, and what comes back depends entirely on how cleanly the enquiry was translated into a specification. The trap is that a trade name does not tell you which product form is covered by which document, and the same alloy carries different grade designations, different UNS numbers and different specifications depending on whether it is supplied as pipe, as a forging or as a wrought fitting.
This cross-reference is built from the ASME BPVC 2023 Section II specifications themselves, so every grade, UNS number and product form below is read out of the specification text rather than from a supplier’s catalogue.
Start with the document, because that is what is ordered
The first question is not which alloy but which document. A material test report is issued against a specification and a grade designation, and a certificate to one specification is not compliance with another. These are the Section II specifications that carry nickel alloys, and what each covers.
| Specification | Product form | Alloy scope |
|---|---|---|
| SA-182/SA-182M | Forgings, flanges, valves, parts | Low alloy and stainless. Contains F 20, F 44, F 51, F 53, F 55, F 60, F 62, F 904L. Does not contain the Ni-Cr-Mo-Cb or Ni-Mo-Cr families |
| SA-403/SA-403M | Wrought stainless fittings | WP and CR grades, including the nickel-bearing ones: WP20CB, WP6XN, WP700, WPNIC, WPNIC10, WPNIC11, WP904L, WP1925 |
| SB-564 | Nickel alloy forgings | The dedicated nickel alloy forging specification. Covers 37 UNS designations, among them N06625, N10276, N06022, N08031, N08034, N06044, N06035, N06058, N06059, N06200, N06686, N06210, N02200, N12160, N06617, N06600, N06603, N06690, N06025, N06045, N06219, N06110, N06230, N04400, N08120, N08800, N08810, N08811, N08825, N06674, N10665, N10675, N10629, N10242, N10624, N08367, R20033 and N10362 |
| SB-729 | Seamless Ni-Fe-Cr-Mo-Cu pipe | N08020, N08026, N08024 |
| SB-464 | Welded Alloy 20 pipe | N08020, N08024, N08026 |
| SB-444 | Cold-worked seamless pipe and tube | N06625, N06852, N06219 |
| SB-622 | Seamless nickel and nickel-cobalt pipe | N10276, N06022, N06044, N06035, N06058, N06059, N06200, N06686, N10362, N08031, N08034, N06210 and N06230, among others |
| SB-167 | Seamless Ni-Cr-Fe pipe and tube | N06600, N06601, N06603, N06690, N06693, N06025, N06045, N06696, N06699, N06617, N06674 |
| SA-312/SA-312M | Austenitic stainless pipe | TP grades including the N-bearing ones such as TP316, TP316L, TP316H and TP304H |
The cross-reference that catches people out
The single most consequential gap in this family is that SA-182 contains no F 625 and no F C-276. A search of the SA-182 text returns zero occurrences of UNS N06625 and zero of UNS N10276.
So an order written as SA-182 F 625 cannot be filled from SA-182. The correct document for a forged Inconel 625 fitting is SB-564, which covers UNS N06625 explicitly, and the correct document for a forged C-276 fitting is also SB-564, which covers UNS N10276. A buyer who writes F 625 and receives a mill quote against SA-182 has received a quote for a grade that does not exist.
Grade name to UNS number, with the product form it belongs to
| Trade or common name | UNS | Grade designation and product form | Specification |
|---|---|---|---|
| Inconel 625 | N06625 | Forging. No SA-182 F grade exists | SB-564 |
| Inconel 625, seamless pipe and tube | N06625 | Cold-worked seamless pipe and tube | SB-444 |
| Hastelloy C-276 | N10276 | Forging; also seamless pipe and tube | SB-564, SB-622 |
| Hastelloy C-22 | N06022 | Forging; also seamless pipe and tube | SB-564, SB-622 |
| Alloy 20 | N08020 | Forging, grade F 20; also WP20CB / CR20CB; also seamless and welded pipe | SA-182, SA-403, SB-729, SB-464 |
| 904L | N08904 | Forging, grade F 904L; also WP904L / CR904L | SA-182, SA-403 |
| Alloy 825 | N08825 | Forging; the wrought fitting grades WP1925 and WP1925N carry N08925 and N08926 | SB-564, SA-403 |
| Super duplex 2507 | S32750 | Forging, grade F 53 | SA-182 |
| Super duplex 6XN | N08367 | Forging, grade F 62; also WP6XN / CR6XN | SA-182, SA-403 |
| 6Mo | S31254 | Forging, grade F 44; also WPS31254 / CRS31254 | SA-182, SA-403 |
| Alloy 800H | N08810 | WPNIC10 / CRNIC10; also covered as a forging | SA-403, SB-564 |
| Alloy 800HT | N08811 | WPNIC11 / CRNIC11; also covered as a forging | SA-403, SB-564 |
| Alloy 718 | N07718 | Not in the SA-182, SA-403 or SB-564 grade lists. A separate nickel alloy forging or bar specification is required | – |
Two rows need a note. 904L does not appear as a grade in SA-312, because SA-312 is an austenitic stainless specification and 904L has its own nickel alloy pipe route. And Alloy 825 shows the pattern you meet throughout nickel alloys: the same alloy family, different UNS numbers per product form.
Read the common name table, because it is in the specification
SA-403 Table 3 is a list of common names, and its footnotes explain what those names are worth. Note A states the naming system was developed and applied by ASTM International. Note C states that a common name is not a trademark widely used and is not associated with any one producer: it describes the alloy, it does not name a brand.
The nickel rows read as follows. WPXM-19 and CRXM-19 are S20910, common name XM-19C. WP20CB and CR20CB are N08020. WP6XN and CR6XN are N08367. WP700 and CR700 are N08700. WPNIC and CRNIC are N08800, common name 800C. WPNIC10 and CRNIC10 are N08810, common name 800HC. WPNIC11 and CRNIC11 are N08811, with no common name given. WP904L and CR904L are N08904, common name 904LC. WP1925 and CR1925 are N08925.
That table is the fastest way to resolve a name a customer uses. If the enquiry says 800HC, the answer is N08810; if it says 904LC, the answer is N08904.
Why the numbers differ between documents
SA-182 Table 2 and SA-403 Table 2 both carry duplex grade families, and a worked example shows why a cross-reference table has to name the document. For F 51, UNS S31803, SA-182 Table 2 gives nickel 4.5-6.5 %, chromium 21.0-23.0 %, molybdenum 2.5-3.5 %. For F 60, UNS S32205, it gives nickel 4.5-6.5 %, chromium 22.0-23.0 %, molybdenum 3.0-3.5 %. These are the two 2205 duplex grades and they are not interchangeable: F 51 is the lower molybdenum grade, F 60 the higher. For F 53, UNS S32750, the super duplex grade, SA-182 Table 2 gives nickel 6.0-8.0 %, chromium 24.0-26.0 %, molybdenum 3.0-5.0 %; F 55, UNS S32760, gives the same nickel and chromium with molybdenum 3.0-4.0 %.
The working rule follows: a UNS number identifies the alloy, and the grade designation plus the specification number identifies the product. A certificate to one document does not satisfy the other, so specify both, always, and never accept a quotation that offers only a trade name.
Procurement checklist
1. Write the specification number and the grade. Trade names are not orderable. 800HC becomes N08810 or WPNIC10; 904LC becomes N08904 or WP904L; 625 becomes N06625 under SB-564 for a forging.
2. State the product form. Forging, wrought fitting, flange, seamless pipe, welded pipe and tube are different documents with different requirements.
3. Give the UNS number as well as the grade. It removes ambiguity about what the mill is supplying, and it is the number that must appear on the test report.
4. Check the marking for the specification you chose. SA-182 clause 19.1 adds QT for quenched and tempered low alloy and martensitic stainless forgings, W for repair welded forgings and WNS where a repair welded austenitic forging has not been postweld heat treated per Table 4, and it requires Grade F 91 to be additionally marked with the appropriate Type. SA-961 clause 20.2 requires the MSS SP 25 marking system with the word steel not substituted for the specification grade.
5. Confirm what the certificate must carry. SA-999 clause 25.2 sets the general test report content: heat number, heat analysis, product analysis, tensile properties, bend and flattening test results, hydrostatic test pressure, nondestructive electric test method and impact test results. SA-403 clause 3.1 adds A960/A960M conformity including any supplementary requirements indicated in the purchase order, and clause 5.3 sets the construction classes: Class S is seamless, while Class W, WX and WU grades are welded with defined radiographic or ultrasonic examination requirements.
6. Do not accept a substitution without the numbers. Require the UNS number, the specification and the grade, and compare the chemistry and mechanical properties from the certification, not the trade name. A different UNS number means a different document and a different certificate.
When an enquiry arrives as a trade name and a product form, the two questions that determine the answer are which document governs and which UNS number it carries. Get those right and the grade designation, the heat treatment, the marking and the certification all follow from the specification. Send us the trade name, the product form and the size and we will confirm the specification, the grade and the UNS number before it goes to a mill. Our nickel alloy butt weld fittings and the wider pipe fittings product range are supplied against the specification and grade confirmed in this way, and the nickel alloy flange range follows the same certification discipline. Request a quotation through the contact page or on WhatsApp at +86 186 2137 7760.
