How to Specify Stainless Steel Washers for an RFQ (Buyer’s Checklist)

Guide · Updated June 2026

An incomplete RFQ wastes time for everyone. A supplier who cannot determine the exact part you need will ask clarifying questions before quoting — and if multiple questions land in sequence, a two-hour job becomes a two-day exchange. The nine data points below are everything a washer manufacturer needs to return an accurate price, confirmed lead time and correct certificate pack on the first pass. Cover all nine and a competent factory can quote within one business day.

The Nine-Point RFQ Checklist

1 Washer Type

Start with the functional type, because it determines the press tool, the strip width and whether the part is in stock or made to order:

• Flat washer — load distribution under a bolt head or nut. The most common type. Includes standard OD (DIN 125 / ISO 7089 / ASME) and small-OD (DIN 433 / ASME SAE).
• Fender washer — large outer diameter for soft, slotted or oversized holes. DIN 9021 is the standard reference.
• Spring washer — split-ring type providing axial spring force against loosening. DIN 127 is the metric standard.
• Tooth lock washer — serrated internal or external teeth that bite into the mating surface. DIN 6798 series.
• Square-hole washer — square centre hole for channel (strut) and structural section steel. See product page.
• Custom / non-standard — any geometry not covered by the above. Provide a drawing. Custom washer page.

2 Standard

Citing a recognised standard number and revision is the most efficient way to communicate all nominal dimensions in a single string. The most common in export trade:

If your drawing calls out a standard and a size, both the standard reference and the size field below are satisfied in one note. For non-standard geometry, skip the standard field entirely and attach a drawing.

3 Size

For metric parts, state the nominal thread size: M2, M3, M4 … M64. This single value, combined with the standard number, fixes the bore, OD and thickness.

For inch parts, state the nominal bolt size the washer is intended for: ¼‑20, 3/8‑16, ½‑13, and so on — or the fractional diameter in decimal inches. Confirm whether you need USS or SAE series, as they share the same bolt size but have different ODs.

For custom or non-standard dimensions, state inner diameter (ID), outer diameter (OD) and thickness explicitly, with tolerances if you have them. Without tolerances, the manufacturer will apply the nearest standard tolerance; if you have tighter requirements, say so upfront.

4 Material and Grade

Three grades cover the vast majority of stainless washer orders:

• 304 / A2 — 18/8 austenitic. The correct default for general indoor structural, food equipment, architectural and most outdoor use where chlorides are absent. Cost-effective and widely stocked.
• 316 / A4 — 316 adds 2–3 % molybdenum, which resists chloride pitting significantly better than 304. Specify 316 for marine, coastal, chemical-process and de-icing environments.
• 316L — low-carbon variant of 316. Specify 316L when washers are incorporated into welded assemblies; the reduced carbon prevents sensitisation in the heat-affected zone.

If you are unsure which grade is correct for your environment, the 304 vs 316 grade guide covers the decision in detail. When in doubt for coastal or chemical exposure, default to 316.

5 Finish

Bright (as-stamped mill finish) is the standard and correct choice for the great majority of industrial, structural and fastener-supply applications. The surface is clean and consistent straight from the press.

Polished finish — mechanically polished to a smoother, more reflective surface — is available on request for architectural cladding, food-grade equipment with strict hygiene-surface requirements, and visible-fastener applications. Polished parts require an additional processing step; state the requirement and the target finish level (Ra value if your specification calls for one) in the RFQ.

Finish has no effect on corrosion resistance in service — grade selection drives corrosion performance.

6 Quantity

State the quantity in pieces for the initial order. Also note:

• Whether this is a one-time order or the start of a repeat programme. Blanket orders with scheduled releases allow the factory to schedule coil purchases and hold tooling, which can shorten per-release lead time.
• Whether you want price breaks quoted at multiple quantity tiers (e.g. 10,000 / 50,000 / 100,000 pcs). A single email with three quantity columns is faster than three separate inquiries.

There is no fixed minimum order quantity to ask about. State what you actually need and the manufacturer will tell you the realistic unit economics.

7 Certificates

Compliance documentation is not automatic — it must be requested and, in some cases, scheduled. State certificate requirements in the RFQ so the factory can confirm availability and factor any additional time into the lead-time quote.

HUIHUI is ISO 9001:2015 certified (cert No. 74326Q00174R001) and has provided MTC (EN 10204 3.1) and PMI documentation on export orders since the factory was established in 2008. Certificate availability and format can be confirmed at quote stage.

8 Packing and Incoterms

Packing: standard export packing for washers is bulk in polybags, packed in cartons on a pallet. If you have a specific requirement — inner packaging (reels, divided boxes, labelled bags), particular carton dimensions, barcode labels, or retail blister cards — state it. Non-standard packing adds cost and lead time; an undisclosed packing requirement discovered at shipment stage causes delays.

Incoterms: state whether you want FOB (you arrange freight from the export port) or CIF (manufacturer arranges freight and insurance to your destination port). For FOB orders, confirm the named port (default: Ningbo). For CIF orders, name your destination port. Both terms are available; HS code 7318.22 applies to flat and fender washers.

9 Drawing or Sample (Custom Parts)

If the part does not conform to any of the standard references above, a dimensioned engineering drawing is the only unambiguous way to specify it. Provide:

• A PDF or DXF with ID, OD and thickness labelled, with tolerances on dimensions that are functionally critical.
• Surface finish notation if not bright.
• Material and grade on the drawing title block or in the email body.
• Annual volume estimate — this determines whether dedicated tooling makes economic sense or whether an existing close die can be adapted.

A photograph of a physical sample is useful context but not a substitute for a dimensioned drawing: tolerances cannot be inferred from a photograph. If you send a sample, also state the critical dimensions you want matched.

For full information on custom washer projects, see the custom washers page.

Common RFQ Mistakes

The following omissions account for most of the back-and-forth between buyers and suppliers in the first quoting cycle:

1. Omitting the standard number. "M8 stainless flat washer" is ambiguous — DIN 125, DIN 433 and ISO 7089 all have M8 variants with different ODs. Add the standard.
2. Specifying 316 when 304 was intended. A grade written incorrectly in the first email is often carried through all subsequent documents. Verify the grade against your application's corrosion environment before sending.
3. Forgetting certificates entirely. A buyer who needs MTC 3.1 but forgets to request it discovers the gap at goods receipt, after the lot has shipped. Tracing documentation retroactively is slow and sometimes impossible.
4. No Incoterm or destination. Without a named Incoterm and port, the supplier can quote the product price but not the landed cost — which means you will need a second exchange before you can make a sourcing decision.
5. Sending a photo instead of a drawing for non-standard parts. A dimensioned drawing takes ten minutes to produce in any CAD tool and eliminates every dimension ambiguity in one step.
6. Not mentioning it is a repeat order. A supplier who knows you are starting a blanket programme can reserve coil and tool capacity; a buyer who treats each call-off as a fresh one-off order will see longer lead times and less competitive pricing.

Frequently Asked Questions