Two flange quotations can only be compared if both suppliers priced the same thing. When an enquiry leaves out the class, facing or bore, each supplier fills the gap differently — and the cheapest quote is often the one that assumed the least. This page shows a worked flange RFQ, line by line, and explains why each column is needed.
Example: A Flange RFQ for a Small Process Package
The lines below are an illustrative example of how a complete flange RFQ reads. Replace the values with those from your own piping specification and line list.
| Line | Type | NPS | Class | Facing | Bore / schedule | Standard | Material and grade | Qty |
|---|---|---|---|---|---|---|---|---|
| 1 | Weld neck | 4" | 300 | RF | Sch 40 | ASME B16.5 | ASTM A182 F316L | 12 |
| 2 | Weld neck | 2" | 300 | RF | Sch 80 | ASME B16.5 | ASTM A182 F316L | 20 |
| 3 | Blind | 4" | 300 | RF | — | ASME B16.5 | ASTM A182 F316L | 4 |
| 4 | Slip-on | 6" | 150 | RF | — | ASME B16.5 | ASTM A105 | 8 |
| 5 | Weld neck | 3" | 600 | RTJ (R-31) | Sch 80 | ASME B16.5 | ASTM A182 F22 Cl.3 | 6 |
Each line can now be priced without assumptions: the supplier knows the forging size, the bore to machine, the facing to cut and the material to certify.
Why Each Column Matters
- Type: weld neck, slip-on, blind, socket weld, threaded, lap joint or orifice — each is a different forging and machining route.
- NPS and class: together they fix the flange dimensions in ASME B16.5 or B16.47; class must be chosen from the pressure–temperature rating of the material.
- Facing: RF, FF or RTJ, with the ring number for RTJ. See RF, RTJ and FF facings.
- Bore / schedule: weld neck and socket weld flanges must match the pipe wall; "as per pipe" forces the supplier to guess.
- Standard: ASME B16.5 (NPS ½–24), B16.47 Series A or B (NPS 26–60 — the two series are not interchangeable), or EN 1092-1 PN flanges.
- Material and grade: the full specification and grade, including class where the grade has classes (for example F22 Class 1 or 3).
Requirements to State Once for the Whole RFQ
- Certificate type: EN 10204 3.1, or 3.2 with the named inspection agency
- Supplementary tests: impact testing, hardness limits (e.g. NACE MR0175), PMI, NDT
- Facing finish and face protection
- Marking, coating (for carbon and alloy steel) and export packing
- Delivery date and Incoterms
Comparing the Quotations You Receive
When the replies come in, check that each supplier has quoted your exact grade, class and facing for every line, and has not added notes such as "bore to suit" or "facing as standard" that change the scope. Compare documents and testing as carefully as price. A complete RFQ makes this a line-by-line check rather than a negotiation.
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