How to approve factory welding and bonding

Define what finished inspection cannot prove

Identify the joint or treated area, its intended function and the failure you need to prevent. For welding, bonding, heat treatment or sealing, ask which properties finished inspection can establish and which need process records or destructive testing. HSE's guidance on plant inspection notes that testing techniques have strengths and weaknesses for different damage mechanisms.

Use the factory audit checklist for the wider capability review. Add a process approval sheet naming the product revision, production site, process owner, evidence required and person authorised to release goods. Ask a competent technical reviewer to identify the applicable product requirements and choose acceptance criteria before trials begin.

Qualify a defined production method

Request the written procedure and supporting qualification results. Match their scope to your materials, joint geometry, thickness, equipment, consumables and production conditions. For bonding, include surface preparation, adhesive identity, mixing, application and curing conditions. A successful trial supports the conditions tested; do not assume it covers a different joint or material.

Agree a qualification trial using production equipment and representative parts. Record actual settings, preparation, environmental conditions and test results, including failures. Have the technical reviewer define the operating limits and explain why the evidence covers your product. Check report identity and scope using test report checks.

Check the people doing the work

Ask who will perform and supervise the process on your order. Match operator evidence to the actual task, method and materials, and check its scope and validity with the issuer where relevant. For automated work, identify who sets up the equipment, controls the programme and authorises adjustments.

For bonding or other tasks without a relevant operator certificate, request task-specific training records, observed practical demonstrations and authorisation against the approved procedure. During the factory visit, compare working practice with that procedure. A certificate in a folder does not show who made your goods or whether they followed the approved settings.

Make destructive samples represent the goods

Agree the destructive test method, acceptance criteria, sample quantity and selection points with the technical reviewer before production. Depending on the failure risk, testing might involve sectioning, bending, pulling or peeling, with conditioning where relevant. Explain how any separate test coupon represents the product's material, preparation, geometry and processing conditions.

Select samples from the actual run or witness representative coupons being made alongside it. Record material and consumable batches, equipment, operator, procedure revision and processing time. Seal and identify samples before dispatch, following the laboratory sample chain of custody guide. Agree who pays for sacrificed goods and replacement samples.

Request individual results, failure locations and photographs rather than only a pass statement. Keep the tested pieces where useful. A passing sample supports the agreed sampling plan; it does not establish the condition of every untested joint. Keep destructive verification separate from qualification evidence and routine production monitoring.

Set release, failure and change controls

Make release conditional on the approved procedure, operator records, actual process records and agreed test results. If a sample fails or a setting falls outside the approved limits, hold the affected production, establish its boundaries and investigate. Agree the disposition and any requalification before accepting repair or restarting production; repeated testing alone is not a corrective action.

Define which changes need technical review, renewed qualification or buyer approval, including changes to material, adhesive, equipment, joint design, site or subcontractor. Use repeat-order change controls to carry these conditions into later orders. Ask Cambridge China Bridge's staff in China to collect and witness the agreed evidence, with technical acceptance assigned to your named reviewer.