What a Fastener RFQ Must Carry So Suppliers Quote the Same Part

Name the governing standard, not a part description

A line that says "3/4 in galvanized bolt" is not quotable, because the standard sets the dimensions, thread tolerances and marking rules the supplier works to. The same nominal part also carries different coating thickness minimums depending on which coating standard is named, so the standard is part of the part definition rather than a note on it. A394 bolts show how far the gap runs. Under ASTM F2329 Supplementary Requirement 1 they need 2.8 mils average and 2.5 mils on any individual specimen; under ASTM A153 Class C the same bolts need 2.1 mils average and 1.7 mils individual ¹. Small fasteners under 3/8 in diameter split the other way, at 1.5 mils under F2329 against 1.4 mils under A153 ¹¹. More zinc on the part changes thread clearance and nut compatibility, so the two answers are not interchangeable ¹. Strength class does not settle the standard either. Grade 8 (SAE J429) and A490 (ASTM F3125) sit at similar strength levels but are different standards and are generally not interchangeable in structural steel without engineering approval ¹⁵. Write the standard number and edition on the RFQ line, and treat any substitution as a documented question rather than a supplier default.

Write the grade and material line so the strength class and embrittlement obligation are fixed

Property class is not just a strength number. It sets the hardness band, and the hardness band decides whether the part sits in the hydrogen embrittlement risk zone and therefore which coating and baking regime is acceptable ^{2, 17}. Class 12.9 runs 39-44 HRC (385-435 HV) and is described as the extreme risk zone, with virtually no tolerance for atomic hydrogen ¹⁷. Class 10.9 runs 32-39 HRC and can tolerate more diffusible hydrogen before crack initiation ¹⁷. Fasteners specified at 25-39 HRC (240-380 HV) are not normally embrittled by galvanizing, which is why class 10.9 and A354 BD bolts are routinely galvanized ². That is why the RFQ should state the property class and the hardness band rather than a tensile figure alone. If you leave the class open, each supplier can quote a different hardness band and a different coating route, and the embrittlement controls priced into the two quotes will not be the same.

Dimension and thread fields the RFQ must carry

A diameter and length alone leaves the supplier to choose the thread system and the gauge that checks it. The thread system also decides whether your coating callout applies, so name both.

• Nominal diameter and pitch, or the thread designation (M, UNC, UNF, UNEF) ¹⁰
• Thread gauging standard to be used alongside the coating standard, for example BS 84 or ASME B1.1 ¹⁰
• Length and the length datum the supplier should measure from
• Head type and drive style
• Point, shank and any under-head geometry that affects assembly
• Coating standard named on the same line, since ISO 10683:2018 applies to non-ISO metric threads including UNC, UNF and UNEF ¹⁰

Write the full coating designation, not a finish word

"Zinc plated" or "zinc flake" cannot be quoted comparably, because the coating standard designation encodes the properties the supplier must deliver. In ISO 10683, the code flZnnc-L-f720 means zinc flake, no hexavalent chromium, lubricant included, fine thickness grade of 5-12 µm, and a minimum 720 hours to red rust in salt spray ⁶. Each element changes the part. Drop the L and the coating carries no lubricant, so the friction coefficient is uncontrolled and the torque-tension relationship is no longer predictable ⁶. The thickness grade and the salt-spray hours are separate decisions: 720 hours is described as standard automotive and general industrial exposure, while 360-500 hours covers indoor moderate conditions and 1000-1500 hours covers severe coastal and offshore service ¹⁰. Hot-dip galvanizing needs the same discipline. F2329 adds mandatory adhesion testing on every batch lot, zero-defect acceptance and higher thickness minimums for small fasteners and A394 bolts, and the source describes a 10-25% cost premium over A153 ¹¹. If your RFQ says only "hot-dip galvanized", suppliers can price either framework and the quotes will not line up.

Volume, order pattern and delivery terms

MOQ, tooling charges and lead time move with size, material and ordering pattern, so a quantity without a schedule is not a comparable enquiry. One supplier's published terms put conventional screws under 10 mm shank diameter at a minimum order quantity of at least 50,000 pcs, with delivery typically 15-25 working days and molds charged separately ²¹. Those are that supplier's terms, not a market rule, but they show why the RFQ has to state the basis. Give the supplier the annual or project quantity, the call-off pattern, and whether tooling is expected to be amortized or charged once. State the delivery terms and destination on the RFQ as well, because the quoted price is built on them. The sources in this set do not publish a standard incoterms or destination field, so write the terms you need rather than assuming a default.

Inspection level, sampling plan and documentation package

Inspection burden follows from the coating standard and the sector, so an RFQ that leaves the level unstated lets each supplier price a different amount of testing.

• Which sampling framework applies — for F2329, state whether a batch lot or a production lot is required, since the customer is responsible for specifying it ^{7, 14}
• Acceptance rule — F2329 references F1470 Table 3 for sample size and the acceptance number is zero defects ⁷
• Certified test results from the shipping lot, or the supplier defaults to Sample Size C and runs the tests ⁷
• Material certificate to EN 10204 3.1 or 3.2 where the part is susceptible ²⁵
• Heat treatment, surface preparation, coating and baking records, plus verification testing records ²⁵
• Sector documentation — FAI, PPAP Level 3, material composition analysis and CoC are often contractually required in regulated sectors ²⁶

Packaging fields you must define yourself

Packaging changes handling cost and unit price, and no source in this evidence set defines the required packaging fields for a fastener RFQ. Write them explicitly instead of accepting a supplier default.

• Unit of pack and quantity per box or carton
• Labeling content and format on the box and the outer carton
• Bulk versus small-box supply, and whether kitting is required
• Any VCI, desiccant or barrier requirement for the shipment
• Returnable or one-way container, and who owns it

Where the sources state different figures for the same decision

Two disputes are worth resolving before the RFQ goes out, because each one changes what a supplier is allowed to price.

FAQ

Related pages

• Manufacturer audits and verification service page
• Manufacturing capabilities service page
• Surface finishes product page
• Reading a Fastener Datasheet: Which Fields You Can Verify, and Which You Must Demand
• ISO Metric vs UNC/UNF Threads: Can You Treat Them as Interchangeable?