Quality Control and Inspection
For an engineering fastener the useful question is not whether a supplier holds a certificate, but whether the properties of the goods delivered match the ones ordered, batch after batch, and whether that can be shown on paper. Our inspection runs from the incoming steel to the packed pallet, and material certificates, factory inspection reports and third-party test results can all be supplied.
Inspection through the process
| Stage | What is checked |
|---|---|
| Incoming material | Steel grade and heat number recorded against the material certificate |
| Forming and thread rolling | Dimensions, thread gauge, head marking |
| Heat treatment | Hardness and mechanical properties against the ordered property class |
| Surface treatment | Coating appearance and thickness; zinc weight where it is specified |
| Final inspection | Dimensions, thread, surface and marking, and batch identity before packing |
Tests we run and tests we arrange
| Property | Method / requirement |
|---|---|
| Hardness | Routine on heat-treated fasteners, to the ordered class |
| Tensile and proof load | To the ordered property class and the applicable standard |
| Neutral salt spray | 240 h, 480 h, 720 h or 960 h depending on the coating system selected |
| Thread | Gauges for the specified thread form, including the trapezoidal thread used on segment bolts |
| Coating weight and thickness | Hot-dip galvanized and Dacromet layers checked against the specification |
The tests listed as routine are run in our own plant. Material certificates and factory inspection reports are issued with the goods, and independent third-party testing — hardness, tensile strength and salt spray in particular — can be arranged when the contract requires it.
Documents supplied with the goods
- Material certificate for the steel used
- Factory inspection report, with results against the ordered property class
- Coating and salt-spray records where a coating system is specified
- Packing list carrying the batch identity, so the goods as packed can be traced back
- Third-party inspection certificates when these are arranged by the contract
What quality means in practice for a project buyer
- Traceable back to the heat. The heat number is recorded when material is received and carried forward, so a question about a delivered pallet can be answered from the records rather than from memory.
- Coating chosen for the environment. A tunnel lining, a coastal façade and an indoor plant room do not need the same system; specifying the salt-spray duration with the exposure usually gives a better result than defaulting to the heaviest coating.
- Sample before batch. A first article is checked against the drawing before the batch runs, which is the cheapest place to catch a thread or a bend that is out of tolerance.
- Consistent marking. Head markings let a bolt on site be identified days after delivery, which matters when material from two batches is on the same pallet.
Request a quotation or send your drawing
Tell us the specification, grade, coating and quantity — or send a PDF/DWG drawing and we will come back with price and lead time.
Tel / WhatsApp / WeChat: +86 185 3100 8199
Email: sales@huilang.top
FAQ
- Do you provide material certificates?
- Yes. A material certificate for the steel used is supplied with the goods, together with a factory inspection report against the ordered property class.
- Can third-party inspection be arranged?
- Yes. Independent hardness, tensile and salt-spray testing can be arranged when the contract requires it, and the resulting certificates are issued with the shipment.
- Which salt-spray duration should we specify?
- It follows the exposure rather than a fixed rule. 240 h is common for protected or indoor service; tunnel, humid and coastal conditions generally call for longer durations. Tell us where the part is installed and we will recommend a coating system with the matching duration.
- How is a delivered batch traced back?
- The heat number is recorded when the material is received and is carried on the packing list, so a delivered pallet can be matched to the material and the inspection records for that production run.