The project specification decides first: a grade it names is not swapped for a general recommendation
Forged Flange Material Grades: How to Choose
Choose the material family from the service first - design temperature, corrosion condition and the project specification - and then state the grade, tests and documents the RFQ needs. The chart below sets the common forged flange families side by side, gives the ASME B16.5 temperature limits where our rating data covers the grade, and links each family to the page that covers it in depth. The three third-party type-test reports issued on flanges from our own production - 16MnD, S22053 duplex and F91 - are compared here, each value kept to its own grade, and each complete report is also linked from its family's page.
Key Points
Pick the family by service: design temperature, corrosion or sour-service condition, then strength
Check the ASME B16.5 material group: it sets the pressure-temperature rating and the temperature limits
Write the grade in full with its tests and documents: impact, PMI, ferrite, hardness, MTC 3.1
Read every published test value as grade-specific: a result belongs only to the grade it was measured on
Forged flange material families: what decides the choice, and where each is covered
| Material family and common grades | Usually chosen for | ASME B16.5-2025 limits we can state | What the RFQ must say | Covered in depth |
|---|---|---|---|---|
| Carbon steel: ASTM A105 / A105N | General pressure piping, utility and refinery service at ordinary temperatures | Material group 1.1. Appendix G lists A105 down to -29 °C (-20 °F). Long use above 427 °C (800 °F) is permitted but not recommended, because the carbide phase may turn to graphite | Normalized condition when the specification asks for it; Appendix G requires heat treatment for A105 flanges of Class 400 and higher | ASTM A105 flanges |
| Low-temperature carbon steel: ASTM A350 LF2 (LF3 or LF6 when specified) | Cold service below the temperature A105 is listed for | The same material group 1.1 ratings as A105. Appendix G lists A350 LF2 down to -46 °C (-50 °F), impact tested | Impact test temperature and minimum energy, heat treatment, and impact results reported on the MTC | A105 vs A350 LF2 guide |
| Austenitic stainless: ASTM A182 F304 / F304L, F316 / F316L | Corrosion service, chemical processing and cryogenic service | F304 and F316 (groups 2.1 and 2.2): Appendix G lists them down to -254 °C (-425 °F) and the rating tables run to 816 °C; above 538 °C (1000 °F) only material with at least 0.04 % carbon. F304L and F316L (group 2.3): not over 454 °C (850 °F) | Full grade wording including L or H, PMI scope and surface condition | Stainless steel forged flanges |
| Duplex and super duplex: ASTM A182 F51, F53, F55 or the project grade | Chloride, offshore and high-strength corrosion service | Not in our rating data: check the grade's own material group and temperature limit in ASME B16.5 before rating the flange | Exact grade wording; NACE MR0175 / ISO 15156 review if the service is sour; PMI, ferrite and PREN when the specification asks | Duplex and super duplex guide |
| Chrome-moly: ASTM A182 F11, F22, F5, F9, F91 | Elevated-temperature, heat-resistant service | Not in our rating data: check the grade's own material group in ASME B16.5 before rating the flange | Grade and class, heat-treatment condition, any hardness limit, simulated PWHT test pieces and the certificate type | Chrome-moly flanges |
| Project-specified grades: EN, GOST or other national wording | When the end user's specification names a grade outside the ASTM families above | Rate it under the standard the project names; do not assume an ASME group from a nearest equivalent | Attach the drawing and material specification; quote any alternate grade separately for approval | EN/DIN vs ASME guide |
Engineering Selection Notes
A material grade is not only a chemistry label. In flange RFQs it controls heat treatment, impact testing, PMI, corrosion suitability, hardness limits, certificate wording and sometimes the pressure-temperature rating path. That is why the same flange drawing can lead to different quotation routes when the material changes.
Carbon steel, LF2, stainless, duplex and alloy grades also behave differently in procurement review. A105 may be familiar and fast to quote, LF2 needs low-temperature evidence, stainless often needs PMI and surface-condition attention, and duplex can introduce ferrite, NACE or project-specific restrictions. The RFQ should show which of those checks is expected before price is compared.
If a buyer is open to material alternatives, it should be stated as a controlled review rather than implied by shorthand. The first offer can then keep the specified grade intact while any alternate grade is presented separately with document and approval assumptions.
Behind the families in the chart sit three separate third-party reports from one type-test campaign. In December 2023 the Zhejiang Academy of Special Equipment Science tested three weld neck flanges taken from our own production and issued one report for each: YSY202450080 on a WN 200-150 RF STD flange in 16MnD, a Chinese low-temperature carbon-manganese forging grade; YSY202450081 on a WN 80-150 RF STD flange in S22053 duplex stainless; and YSY202450082 on an NPS4 Class 150 flange in F91 chrome-moly. All three were judged pass. Each complete report is also linked from its family's pages: the 16MnD report from the A105 vs A350 LF2 guide, the S22053 report from the duplex guide and the stainless flange page, and the F91 report from the chrome-moly flange page. Their data pages are shown as figures on the A105 vs A350 LF2 guide, the duplex guide and the inspection document checklist. This page keeps the comparison between them.
What each report measured is not the same, and that matters more than the three pass verdicts. Only the 16MnD report carries impact testing - six Charpy values at -45 °C. Only the S22053 report carries a metallographic ferrite reading. Only the F91 report carries hardness in HBW. Where a test was not run, the report prints dashes, and this page prints the dashes too. A value measured on one of those three flanges says nothing about the other two, so no number on this page is carried across a grade boundary.
The second kind of paper on this page works differently. TÜV NORD assessed our forged flange and forging materials against ASME Section II Part A and issued a material conformity certificate whose Annex I lists the standards and grades covered: SA-105, SA-182, SA-266, SA-350 and SA-765. That annex is a scope statement about which material specifications an outside body has assessed at this plant. It carries no test value for any grade, and a grade appearing on it is not evidence that a particular flange met it.
Direct Answers with Evidence
Which material standards has an outside body assessed at your plant?
Five, as a scope statement rather than as test results: our forged flange and forging materials are certified to ASME Section II Part A by TÜV NORD, and Annex I of that certificate lists SA-105, SA-182, SA-266, SA-350 and SA-765.
Evidence
- TÜV NORD Certificate of Conformity No. CER-IND1105842412004001 Rev. A, ASME BPVC Section II Part A, product line 'Forged Steel Flanges and Forgings', certification type type approval plus factory inspection
- Annex I as printed: SA-105/SA-105M with a dash in the grades cell, SA-182/SA-182M with F304 through F91 - F9 is printed twice, so the cell holds 25 entries and 24 distinct grades - SA-266/SA-266M with Grade 1 to 4, SA-350/SA-350M with LF2, LF3 and LF6, and SA-765/SA-765M with Grade I to V
- One merged size cell applies to every row of the annex: thickness max 550 mm, weight max 7000 kg
- The certificate states its own dates: issued 25.02.2025, valid to 24.02.2028, subject to annual surveillance audit
Applies when
Useful at vendor-registration or prequalification stage, when the question is which material specifications an outside body has already assessed at our plant rather than what a particular flange measured.
Limits
The certificate says in its own words that it is based on the evaluation of samples, that it does not imply an assessment of the production of the product, and that it does not permit use of a TÜV NORD mark - which is why the fact is stated here in text and no TÜV badge appears anywhere on this site. It is a material conformity certificate: not an ASME Code stamp authorization, not a quality-system certificate and not a per-order release. Its validity is conditional on the annual surveillance audit, so ask for the current signed annex page if your approval process has to see it. Annex I prints grade designations only and does not map them to UNS numbers, and a grade appearing on it is not evidence that any particular flange met that grade.
Can these three reports stand in for the material certificate on my order?
No. They are type tests on samples under TSG D7002-2023 and belong in a supplier-qualification file; the order itself still needs its own EN 10204 3.1 MTC tied to the delivered heat.
Evidence
- All three reports belong to type-test certificate TSXY741010027202450009, which runs from 2024-01-11 to 2028-01-10 and whose printed material scope names carbon steel, low-alloy steel whose specified minimum tensile strength is 540 MPa or below, chrome-moly steel, alloy steel whose specified minimum tensile strength is above 540 MPa, alloy steel with a design temperature below -40 °C, stainless steel and duplex stainless steel
- The test body tested two pieces per grade and states that keeping production consistent with the type-tested sample remains the manufacturer's responsibility
- Non-destructive testing on all three samples is recorded as piece-by-piece ultrasonic examination whose result column states that our own UT report was reviewed and confirmed by the test body - to NB/T 47013.3-2015 Class I on the 16MnD and S22053 samples, to ASTM A388/A388M-23 on the F91 sample
Applies when
Use them where our process capability across material families is the question: a prequalification pack, a vendor registration, or a first enquiry asking whether we have forged and passed a given class of material at all.
Limits
They prove nothing about your heat, your size or your pressure class. The tested articles were DN200, DN80 and NPS 4, all Class 150, so a Class 900 or an NPS 24 flange sits outside what was sampled. The ultrasonic lines were not examinations performed by the test body: our plant ran the UT and the test body reviewed and confirmed our report, so none of this can be described as UT performed by a third party. And each report answers only for its own grade - there is no read-across between the three.
Source Basis
- ASME B16.5-2025 pressure-temperature data, as carried by our rating calculator - the temperature limits in the selection chart come from the material-group notes and the Appendix G (Table G-1) values this calculator carries for groups 1.1, 2.1, 2.2 and 2.3
- Type-test report YSY202450080, 16MnD - complete PDF (Zhejiang Academy of Special Equipment Science) - every 16MnD value on this page comes from section III, report pages 4 and 5
- Type-test report YSY202450081, S22053 - complete PDF (Zhejiang Academy of Special Equipment Science) - every S22053 value on this page comes from section III, report pages 4 and 5
- Type-test report YSY202450082, F91 - complete PDF (Zhejiang Academy of Special Equipment Science) - every F91 value on this page comes from section III, report pages 4 and 5
- Special equipment type-test certificate TSXY741010027202450009 - the certificate all three reports belong to; its printed material scope names the families they cover
- ASME BPVC Section II Part A material conformity certificate issued by TÜV NORD - Annex I lists the SA-105, SA-182, SA-266, SA-350 and SA-765 grades assessed, with one size limit covering every row
- ASTM A182/A182M - forged flange material specification (scope page) - the specification the F91, F304, F316 and F51 grade wording in this guide refers to
What each of the three type-test reports measured, and what it left untested
| Test row in the report | YSY202450080 - 16MnD, WN 200-150 RF STD | YSY202450081 - S22053, WN 80-150 RF STD | YSY202450082 - F91, NPS4-CL150 WN-RF |
|---|---|---|---|
| Product and material standard on report page 1 | HG/T 20615-2009 and NB/T 47009-2017 | HG/T 20615-2009 and NB/T 47010-2017 | ASME B16.5-2020 and ASTM A182/A182M-23 |
| Chemistry | 9 elements carry printed limits, every measured value inside | 9 elements carry printed limits, every measured value inside | 12 elements carry printed limits, every measured value inside |
| Yield strength Rp0.2, two specimens | 383 MPa / 412 MPa against min 305 MPa | 532 MPa / 523 MPa against min 450 MPa | 544 MPa / 555 MPa against min 415 MPa |
| Tensile strength Rm, two specimens | 529 MPa / 551 MPa against a 480-630 MPa band | 763 MPa / 759 MPa against min 620 MPa | 706 MPa / 709 MPa against min 620 MPa |
| Elongation A, two specimens | 25.5% / 27.0% against min 20% | 45.0% / 50.0% against min 25% | 27.5% / 28.5% against min 20% |
| Impact energy | six values, 175.0 J / 206.5 J / 210.0 J and 180.0 J / 236.5 J / 283.0 J against min 47 J, remark column recording -45 °C | not tested - the row is dashes and the verdict cell is a dash too | not tested - the row is dashes, although the verdict cell beside it reads pass |
| Hardness HBW | not tested - both hardness rows are dashes | not tested - the remark reads that the material has no hardness requirement | six readings, 212 / 218 / 210 HBW and 219 / 213 / 213 HBW against a 190-248 HBW window |
| Metallographic examination | not tested - the row is dashes | ferrite content 55% and 55% against a 40-60% window | not tested - the row is dashes |
| Sealing face roughness, two specimens | Ra 5.8 / Ra 5.9 against Ra 3.2-6.3 | Ra 5.2 / Ra 5.1 against Ra 3.2-6.3 | Ra 5.2 / Ra 5.2 against Ra 3.2-6.3 |
| Ultrasonic examination | piece-by-piece UT to NB/T 47013.3-2015 Class I; our UT report reviewed and confirmed by the test body | piece-by-piece UT to NB/T 47013.3-2015 Class I; our UT report reviewed and confirmed by the test body | piece-by-piece UT to ASTM A388/A388M-23; our UT report reviewed and confirmed by the test body |
| Reduction of area Z and grain size | neither is listed in the report | neither is listed in the report | neither is listed in the report |
| Heat-treatment parameters | no temperature, soak time or cooling medium anywhere in the document | no temperature, soak time or cooling medium anywhere in the document | no temperature, soak time or cooling medium anywhere in the document |
Annex I of TÜV NORD certificate CER-IND1105842412004001 Rev. A, transcribed as printed
| Standard code as printed | Grades printed in Annex I | Size limit printed in Annex I | What the row is |
|---|---|---|---|
| SA-105 / SA-105M | the grades cell is a dash - this standard is not subdivided into grades | thickness max 550 mm, weight max 7000 kg | a material specification inside the assessed scope; no test value is attached to it |
| SA-182 / SA-182M | F304, F304L, F304H, F316, F316L, F316Ti, F321, F321H, F317, F317L, F347, F904L, F11, F12, F22, F44, F1, F5, F9, F51, F53, F55, F60, F91 - F9 is printed twice, so the cell holds 25 entries and 24 distinct grades | one merged size cell in Annex I applies the same limit to every row | the austenitic, duplex and chrome-moly grade wording sits inside the assessed scope; the certificate maps no grade to a UNS number |
| SA-266 / SA-266M | Grade 1, 2, 3, 4 | same merged size cell | carbon steel forgings for pressure vessels are inside the assessed scope |
| SA-350 / SA-350M | LF2, LF3, LF6 | same merged size cell | the low-temperature forging standard is inside the assessed scope; the certificate carries no measured value for LF2 |
| SA-765 / SA-765M | Grade I, II, III, IV, V | same merged size cell | the low-temperature-toughness forging standard is inside the assessed scope as well |
Practical Checklist
- Carbon steel: ASTM A105, A105N or project-specific carbon steel wording
- Low-temperature steel: ASTM A350 LF2 or LF6 with impact test requirements
- Stainless steel: ASTM A182 F304/F304L, F316/F316L or related grades
- Duplex and super duplex: F51, F53, F55 or project-specified equivalent
- Alloy steel or nickel alloy requirements when specified by the end user
- Chrome-moly: ASTM A182 F11, F22, F5, F9 or F91 with heat-treatment and hardness requirements
- Design minimum and maximum temperature, so the grade can be checked against its B16.5 limits
- Heat treatment, hardness, PMI, NDT and MTC 3.1 document requirements
- Which tests must be run on the delivered heat, and which may be covered by qualification-stage records
- Quantity, destination and whether material substitution is allowed
Common RFQ Mistakes
- Treating A105 and LF2 as interchangeable without checking temperature service
- Omitting normalized, impact test or heat treatment requirements
- Using stainless grade shorthand without confirming full ASTM wording
- Approving duplex or stainless alternatives without checking corrosion service and PMI requirements
- Leaving hardness, NACE, ferrite or project-specific material notes out of the first RFQ
- Reading a test result measured on one material grade as evidence for a different grade
- Treating a supplier type-test report as the material certificate for the delivered heat
- Ordering an L-grade stainless flange for service above 454 °C (850 °F)
FAQ
Is a short material name enough for quotation?
Usually no. The RFQ should state the full grade wording, standard, heat treatment or condition, certificate requirement and whether substitution is allowed.
When does PMI become important?
PMI is especially important for stainless, duplex, alloy or mixed-grade orders where grade verification must be visible before shipment or third-party release.
Can BLD quote alternative materials?
Alternatives can be reviewed when the buyer allows substitution. The original specified grade and any alternate grade should be separated so approval assumptions are clear.
Do you have third-party test data on materials you actually forged?
On three grades, from one type-test campaign. The Zhejiang Academy of Special Equipment Science tested three weld neck flanges from our shop in December 2023 and issued one report each: YSY202450080 on 16MnD, with six Charpy values from 175.0 to 283.0 J at -45 °C against a 47 J minimum; YSY202450081 on S22053 duplex, with 55% ferrite on both specimens against a 40-60% window; and YSY202450082 on F91, with six hardness readings inside a 190-248 HBW window. All three complete PDFs are linked on this page and from each family's page - the A105 vs A350 LF2 guide, the duplex guide and the chrome-moly flange page - and the table on this page compares what each measured and left untested. Each set of numbers belongs to its own grade, 16MnD is not A350 LF2, and a type test on two samples is not batch release.
What does the TÜV NORD ASME Section II Part A certificate actually cover?
It covers materials, on a sampling basis. TÜV NORD assessed our forged flange and forging materials against ASME BPVC Section II Part A and issued Certificate of Conformity CER-IND1105842412004001 Rev. A on a type approval plus factory inspection basis; Annex I of that certificate lists the standards and grades assessed, and this page transcribes it as printed. The certificate states in its own words that it is based on the evaluation of samples and does not imply an assessment of the production of the product. It is not an ASME Code stamp authorization, not a quality-system certificate and not a per-order release, and its validity is conditional on an annual surveillance audit. We describe it as materials certified to ASME Section II Part A by TÜV NORD, and never as anything wider than that.
Can A105 flanges be used below -29 °C?
Not on the ASME B16.5 default: Appendix G lists A105 down to -29 °C (-20 °F). For colder service the usual route is an impact-tested low-temperature grade such as ASTM A350 LF2, which Appendix G lists down to -46 °C (-50 °F), unless the governing piping code and the project specification set another rule. State the design minimum temperature in the RFQ so the grade can be checked against it.
When is an L-grade stainless flange the wrong choice?
When the design temperature is over 454 °C (850 °F): ASME B16.5 ratings for F304L and F316L (material group 2.3) end there. Above 538 °C (1000 °F) B16.5 also asks for F304 or F316 material with at least 0.04 % carbon - the H grades, or standard grades that meet it - so state the design temperature, not only the grade name.
Author & Verification
Written by: Tom Fan, Sales Director, BLD Forge Direct (Shanxi Baolongda Forging Co., Ltd.)
Reviewed by: BLD QC Engineering Team - in-house laboratory, CNAS L24083
Last verified: 2026-10-22
Revision log
- 2026-10-22 - Rebuilt as a selection page. A material-family chart now leads the page: the ASME B16.5-2025 temperature limits our rating data covers, what the RFQ must say, and a link to the page that covers each family in depth. The three type-test data figures and the three per-grade evidence units moved out: the complete reports stay linked here and from each family's page (16MnD from the A105 vs A350 LF2 guide, S22053 from the duplex guide and the stainless flange page, F91 from the chrome-moly flange page), and the data pages remain as figures on the A105 vs A350 LF2 guide, the duplex guide and the inspection document checklist. The side-by-side table of what each report measured and left untested, the Annex I transcription and the two cross-grade evidence units stay here.
- 2026-09-19 - Added the third-party material evidence: the three type-test reports issued by the Zhejiang Academy of Special Equipment Science on our own flanges - YSY202450080 (16MnD), YSY202450081 (S22053) and YSY202450082 (F91) - each data page published as its own figure with the complete PDF attached, a side-by-side table of what each report measured and left untested, the Annex I grade matrix from the TÜV NORD ASME Section II Part A certificate transcribed as printed, five evidence units and this block. Every value is attributed to the single report it came from; no number is carried across a grade boundary. What the reports do not contain - reduction of area, grain size, heat-treatment parameters, impact on two of the three grades, hardness on two of the three - is written into the table rather than left out.
- 2026-06-13 - Material grade guide, selection matrix and FAQ baseline version.
PDF Datasheets for RFQ Review
ASTM A105 Flanges RFQ Datasheet
Use this PDF for common carbon-steel forged flange RFQs.
Stainless Steel Forged Flanges RFQ Datasheet
Use this PDF when stainless, duplex, PMI or corrosion-service requirements are part of the RFQ.
Send your RFQ or drawing directly to BLD Forge Direct.
Email quote@bldforgedirect.com with standard, drawing, material, quantity and inspection requirements.