13 · Structural · clamp language on print
Torque vs preload vs proof load on RFQ drawings
On stone cladding brackets, structural splices, and heavy baseplates, a single “tighten to …” note often mixes three different ideas: installation torque (wrench reading), preload / clamp force (axial force the joint needs), and proof load (a product or lot verification level — not a site snug target). Lock which figure the controlling revision owns before any unit price is useful — this desk does not publish torque charts.
Define · what this RFQ is for
Use this desk when overseas buyers quote Dashitou stone · structural · heavy fasteners and the print must separate torque callouts, preload / clamp intent, and proof-load language (when the buyer standard names it). You own joint design and engineer sign-off; we confirm which figure appears on the revision, lubrication / dry-vs-lubed notes, diameter × length, and qty band against that revision.
Pair with structural bolt class & coating (G8) when property class/finish matter, thread engagement vs grip (G11) when stack-up drives length, flange vs hex head (G12) when under-head bearing changes friction, and drawing handoff for revision lock. Then open Enquire / RFQ.
Discuss · fields that change the quote
Each row below is a desk check. Missing rows stay Open — we do not invent K-factors, μ tables, or proof-load charts on this public page.
Field desk · 01–06
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Which figure the print owns Name installation torque, target preload/clamp, or proof-load / lot verification explicitly. “Tighten per standard” without naming the figure invites dual quotes.
- Email example: Print owns installation torque (lubricated) per Rev D — not proof load
- If missing: Open — do not invent a site torque from a catalog table
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Lubrication / dry vs lubed Torque without a dry/lubed note is incomplete. Name paste, oil, or dry as the revision states. Preload intent often needs the same friction assumption written beside it.
- Email example: Torque 210 N·m lubricated (MoS2 paste) · dry not allowed (Rev D)
- If Open: mark preference on the print or RFQ notes
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Proof load vs site snug Proof load is typically a product/lot verification level under a named standard — not the same as “snug on site.” If the BOM says proof load, say whether that is mill/lot test language or a field target. Do not treat them as interchangeable on this desk.
- Email example: Proof load = mill lot test per buyer std; site = torque callout only
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Class / finish / nut set Property class and coating still matter — see G8. Finish and nut face condition affect achieved preload at a given torque; keep them on the same revision as the clamp note.
- Email example: Class 8.8 zinc flake + matching nut; torque callout lubricated
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Qty band & destination Mock-up joint set vs project lot; destination for packing notes. Discussion band is enough for the first reply.
- Email example: Qty band: mock-up 80 pcs → project lot TBD · dest EU
What must appear on the print
- Named figure: installation torque vs preload/clamp vs proof-load / lot language
- Dry vs lubricated (or paste brand when the revision names it)
- Diameter × length and joint type (through-bolt vs tapped) when clamp matters
- Controlling revision — see drawing handoff
Agree · before we number
Until the following are aligned, treat any figure as discussion only:
- Controlling revision locks which clamp figure owns the joint (or marks Open with a preference rule)
- No invented torque, K-factor, μ, or proof-load tables posted as site policy here
- Lubrication, class/finish, and grip/head notes settled or linked (G8 / G11 / G12) in the same thread
- Samples and private-label marking only after the clamp figure and diameter × length are clear
We do not invent certificates, plant area, or ranking badges here. Project documents that matter to the RFQ are shared privately when relevant.
FAQ · torque vs preload vs proof load
Is “tighten per standard” enough to quote torque or preload?
Usually no. Installation torque, target preload, and proof-load language are different figures. Name which one the controlling revision owns, or mark Open with a preference rule. Vague “per standard” language often forces a resubmit.
When should an RFQ lock preload instead of a wrench torque?
When the engineer owns axial clamp force (or elongation / tension method) and torque is only a site approximation. Do not convert preload into a site N·m chart on this public desk without the print. Write dry vs lubricated beside either figure.
Is proof load the same as the site snug or install torque?
Usually not. Proof load is typically a product or lot verification level under a named buyer standard. Site snug / install torque is a field callout. Treat them as separate lines unless the revision explicitly equates them.
Can one RFQ mix torque-controlled and preload-controlled zones?
Yes, when zones are explicit on the BOM (for example torque on cladding brackets, preload method on heavy splices). Ambiguous “torque/preload OK” without zone ownership often splits the quote. Lock zones or mark Open with a preference rule.
What should I send so Dashitou can review clamp language cleanly?
Open Enquire / RFQ, then email the PDF/STEP or marked sketch to shizhanhao6@gmail.com in one thread. Include which figure the print owns, dry/lubed note, diameter × length, joint type if relevant, class/finish if relevant, qty band, and destination. Skim G8, G11, and G12 when those desks apply. No cart; no list prices on this site.
Next step
Skim structural bolt RFQ · engagement vs grip RFQ · flange vs hex RFQ · RFQ checklist, then open Enquire / RFQ. Direct email: shizhanhao6@gmail.com.