Fasteners Quality Control TestingBefore the Carton Is Sealed
We run fasteners quality control testing at every production stage — material verification, dimensional inspection, hardness, tensile, coating thickness and salt spray. Each test attaches to a batch, so the report you receive matches the fasteners you receive.
Fasteners Quality Control Testing: What We Check, and Why
Each test below exists because a specific failure mode is common in fastener supply. This is not a marketing checklist — it is the set of checks that catch problems before shipment.
Material Verification for Fasteners Quality Control
We check steel grade and heat number against the mill certificate before releasing material to production. This catches mixed material before it becomes a finished bolt.
Chemical composition · Heat number · Mill certificate
Dimensional Inspection in Fasteners Quality Control
We check head dimensions, shank diameter, thread pitch, thread length and overall length against the applicable standard, not against a sample photo.
Thread gauge · Micrometer · Runout · Length
Hardness Testing for Fasteners Quality Control
We measure hardness after heat treatment, not before. This confirms that quenching and tempering achieved the property class instead of assuming it from the furnace setting.
Rockwell / Brinell · Surface & core · Per batch
Tensile & Proof Load in Fasteners Quality Control
We measure tensile strength and proof load on a universal testing machine. This is the check that confirms the bolt carries the load the property class promises.
Tensile strength · Proof load · Yield strength
Coating Thickness Testing for Fasteners Quality Control
We measure zinc plating, hot dip galvanizing and Dacromet with a coating thickness gauge after processing. We do not infer thickness from the bath parameter.
Zinc plating · HDG · Dacromet · µm per batch
Salt Spray Testing for Fasteners Quality Control
We use salt spray data to support the corrosion class specified for coastal and high-humidity sites, which is common for GCC and West African projects.
Neutral salt spray · Hours to red rust · Per coating type
Where Fasteners Quality Control Testing Happens
Testing is not a single room at the end of the line. Each checkpoint below catches a different failure mode at the stage where we can still correct it.
01 · Incoming Material
We check chemical composition, heat number and mill certificate before releasing material to production.
02 · After Heading
We check head dimensions, shank diameter and overall length against the applicable standard.
03 · After Thread Rolling
We check thread pitch, thread length, gauge fit and runout with go/no-go gauges.
04 · After Heat Treatment
We measure hardness and tensile strength after treatment instead of assuming them from the furnace setting.
05 · After Coating
We measure coating thickness, then re-check the thread gauge to confirm the coating did not close the thread.
06 · Before Packing
We check final dimensions, quantity, labelling and carton condition against the order.
07 · Documentation
We file the material certificate, mechanical report and coating data against the batch, then issue them with shipment.
08 · Third-Party
We schedule SGS, BV or customer-nominated inspection at the correct stage, not after packing.
一次螺纹通止规复检，避免了一批货到港后被拒
一批 M20 热镀锌六角螺栓，镀锌后按常规只抽检了涂层厚度，厚度在 65–80 µm 之间，符合要求。但在发货前的螺纹通止规复检中，我们发现约 3% 的螺栓通规无法顺利旋入到底。
原因是热镀锌后螺纹牙顶的锌层厚度局部超过 90 µm。涂层厚度检测点在杆部合格，但牙顶位置没有单独测量。我们让该批货全部重新过通规，把不合格的挑出后重新回牙，并调整了下一批镀锌后的离心参数。后续批次在镀锌后增加了牙顶位置的单独测厚点。
如果只做涂层厚度、不做镀锌后的螺纹复检，这批货到中东港口后会被采购方以”无法装配”为由拒收。返工和滞港成本远高于出厂前的一次复检。
What You Receive With Each Fasteners Quality Control Testing Order
We issue documents against the batch, not against the catalogue. The set below is the default; we can add more when the project specification requires them.
Material Certificate
Steel grade, heat number and chemical composition traceable to the incoming mill certificate.
Mechanical Report
Hardness and tensile results for the batch, with the test method stated.
Dimensional Report
Key dimensions and thread gauge results against the applicable standard or drawing.
Coating & Salt Spray Data
Coating thickness measurements and salt spray hours, where the project requires corrosion data.
How to Request Fasteners Quality Control Testing Documents
Test documents only help if they match the batch you receive. When you request documents, state the standard, property class and coating requirement, so we can match the report to the correct specification instead of issuing a generic one.
| Request | What to State |
|---|---|
| Material certificate | Standard, grade, heat number requirement |
| Mechanical report | Property class, test method, sample size |
| Dimensional report | Standard or drawing, critical dimensions |
| Coating data | Finish type, thickness range, salt spray hours |
| Third-party inspection | Agency name, inspection stage, scope |
Fasteners Quality Control Testing Questions Buyers Ask
These are the questions procurement teams send us most often when they review fastener test documents.
Do you issue test reports per batch or per order?
We issue reports per batch. Each production batch carries a heat number from the incoming material, and we file the mechanical, dimensional and coating results against that batch. If an order contains several batches, you receive several sets of reports. A generic catalogue report cannot be matched to the fasteners you actually receive, so we do not use one.
Can you arrange third-party inspection before shipment?
Yes. We schedule SGS, BV or a customer-nominated agency before shipment. Timing matters: we plan inspection at the correct production stage, not after packing. An inspector who only sees packed cartons cannot detect heat treatment problems. Tell us the required stage when you request inspection.
What salt spray hours should I specify for a coastal site?
Take the salt spray hours from the project specification, not from a general rule. As a reference, buyers usually specify zinc plating for indoor or sheltered use, hot dip galvanizing for outdoor structural and coastal work, and Dacromet where zinc plating is insufficient but hot dip galvanizing would affect thread fit. Start from the corrosion class in the specification.
Do you test every batch or only sample batches?
We run mechanical and dimensional tests on each production batch. Within a batch, sampling follows the applicable standard or the customer’s inspection plan. If the project requires 100% dimensional inspection or full batch mechanical testing, state this at inquiry stage so we can include it in the quotation instead of adding it later.
Can you test fasteners produced elsewhere?
We can run dimensional, hardness and coating thickness checks on supplied samples, but we cannot reconstruct material certification or heat treatment history for fasteners that did not come from our plant. If you need to verify an existing stock, a third-party laboratory with its own accreditation is the more reliable route, and we will tell you so rather than issue a report that overstates what we can confirm.
What happens if a test result falls outside specification?
We hold the batch and do not pack it. Depending on the failure, we either rework it (for example, re-temper or re-coat) and retest, or reject and replace it. We inform the customer before shipment, not after. A test report that shows “pass” for every batch is a warning sign, not a reassurance.
Need Fasteners Quality Control Testing Documents?
Tell us the standard, property class, coating requirement and destination port. If you need third-party inspection, name the agency and the stage at which inspection should take place.
Confirm test scope and documentation against the applicable project standard and order specification.