Bolt property classes help identify the mechanical-property requirement for a fastener. Keep the class separate from the thread size, length, head form and other details needed to identify the ordered item.
Consider a fictional aluminum-bracket order. The released hardware list specifies one steel screw class. A seller offers a different class as an upgrade, while leaving the same nominal thread diameter in the quotation.
The purchasing action is to identify the change and obtain the responsible designer’s review. A similar size or a larger class label does not complete that review.
Make a proposed change visible
- Keep the complete original fastener specification.
- List the alternative as a separate proposal.
- Record the technical decision before revising the order.
On this page
Check 1: read bolt property classes as labelled properties
Böllhoff’s eighth-edition fastening manual, available through its publication page, explains the two numbers separated by a dot for steel screw classes. Its class 5.6 example gives a tensile-strength value of 500 N/mm² and a yield-limit value of 300 N/mm².
The manual also distinguishes nominal and minimum entries in its mechanical-property table, including diameter-specific columns for class 8.8. Use the applicable table and footnotes rather than treating label arithmetic as a complete property specification.
This is a reading example from the identified publication. It is not a measured result for hardware in the image or a specified load for an aluminum connection.
Keep each quantity and unit beside its heading when transferring data. A class label, a tensile-strength entry and a finished-fastener test result should remain separately identified.
Ask the supplier to identify the product specification and the property requirements applicable to the actual offered item. Retain the edition or controlled reference used for the order review.
If a certificate contains several results, map each result to the corresponding requirement. Do not select one convenient number and use it as a general description of the fastener.
Check 2: use the table that covers the actual product
Begin with the precise hardware reference in the quotation. Ask which product, size and supplied condition its supporting documentation covers.
A comparison should preserve whether a listed number is nominal information, a minimum requirement or an observed result. Changing the heading can change the meaning even when the digits remain the same.
Read the diameter range and relevant notes before copying a property row. If the quoted item sits outside the range covered by the attached sheet, ask for the appropriate documentation.
Keep the test requirement and test result in different fields. State what the order requires and which record is offered as evidence.
Ask whether the agreed documentation concerns starting material or finished fasteners. Preserve that scope instead of relabelling an upstream record as evidence for every characteristic of the delivered item.
The complete property requirement may contain more than the familiar tensile-strength line. Request the relevant specification rather than relying on a seller’s abbreviated description.
This guide does not provide a complete standards table or certify conformity. Use the governing purchase specification and applicable product documentation for an actual acceptance decision.
Check 3: keep the rest of the fastener identity complete
Put the class in a dedicated field within a complete hardware description. Retain the thread designation, length, head and drive form, product reference, finish and other controlled requirements.
Our screw-length and thread-length guide explains why those two dimensions need separate headings. A class label does not fill in missing dimensional information.
Identify the mating component and the drawing revision where the hardware is used. For an aluminum assembly, keep the actual hole, internal-thread or insert arrangement visible in the drawing set.
Our aluminum thread-insert guide organizes that component information. The fastener supplier still needs the approved hardware specification for the particular joint.
Keep surface treatment and supplied condition explicit in the commercial description. A short strength-class line should not replace the rest of the controlled item identity.
If a quotation covers several screws, use separate line items where their specifications differ. Avoid a shared note that leaves the seller to decide which requirement applies to each position.
Compare the order line with the packing and delivery references. Similar fasteners stored together should still have the identification needed by the agreed receiving process.
A simple way to review the seller’s proposed upgrade
Return to the fictional bracket order. Put the released specification in one column and the proposed alternative in another. Keep the seller’s reason for the change alongside the proposed item.
| Review field | Decision to record |
|---|---|
| Hardware identity | Which fields match and which have changed? |
| Supporting documents | Which specification and evidence cover the proposed item? |
| Technical review | Who accepts or rejects the alternative for the actual joint? |
| Order revision | Which released reference records the final decision? |
Ask the responsible designer to review the proposal against the actual connection. Do not accept a commercial upgrade label as the engineering decision.
Retain any approved change to associated assembly instructions. Our torque and preload guide explains the separate review of tightening records and joint conditions.
If the seller cannot provide the complete alternative specification, leave the change unresolved. A lower price, faster delivery or reassuring photograph does not supply the missing technical information.
If the designer approves the alternative, update the controlled hardware reference and retain the decision with the order. Make the delivery check refer to that revised requirement.
The fictional case does not establish that any particular class is suitable or unsuitable. It supplies a purchasing review sequence, without a joint-load calculation or tightening setting.
Connect the evidence to the delivered fasteners
Agree the documentation package before placing the order. Identify the applicable product reference, quantity, batch information and inspection evidence expected at delivery.
Make the scope of any test record visible. Ask which supplied items it covers and how the identifiers connect to the packing list.
Where the approved receiving process calls for marking checks, compare the actual delivered identification with the required documentation. Escalate an unexplained difference rather than editing the certificate to match the photograph.
Keep findings factual. Record an unreadable mark, missing reference or document mismatch as the observation it is, then obtain the responsible supplier’s clarification.
For aluminum part preparation, define what the component supplier is delivering. A cut blank, machined bracket and assembled product have different scope descriptions; mark the requested stage in the enquiry.
Quick answers for the order review
Does a larger class label approve a replacement?
Obtain the responsible designer’s review of the complete proposed item and actual connection.
Can the class replace the full screw specification?
Retain the geometry, product reference, supplied condition and controlled requirements alongside it.
Does a brochure value prove delivered conformity?
Check the applicable requirement and the evidence linked to the delivered batch.
Keep hardware requirements with the aluminum drawing
Send JiurunCut the stock drawing and required manufacturing scope. Keep bolt property classes and complete hardware references in the relevant controlled documents so downstream assembly requirements remain clear.