At any point in the course of welding, i.e. tacking, root pass, filler pass or capping pass, but particularly for the root and cap, a detailed inspection may be required. British Standard 5289: 1976 gives guidance on tools and responsibilities together with sketches of typical defects.
The inspector at this point must -
a) observe, identify and perhaps record (measure) the features of the weld.
b) decide whether the weld is acceptable in terms of the particular levels that are permitted; defect levels may be ‘in-house’ or national codes of practice.
When the defect size is in excess of the permitted level then either a concession must be applied for (from a competent person), or the weld rejected.
INSPECTION BEFORE WELDING
Check * All applicable documents.
* Quality plan is authorised and endorsed with signature, date and company stamp.
* Application standard is up to date with the latest edition, revision or amendment.
* The drawings are clear, the issue number is marked and the latest revision is used.
* Welding procedure sheets (specifications) are available, have been approved and are
employed in production.
* Welder qualifications with identification and range of approval are verified and that only approved welders as required are employed in production.
* Calibration certificates, material certificates (mill sheets) and consumer certificates are available and valid.
* Parent material identification is verified against documentation and markings.
* Material composition, type and condition.
* Correct methods are applied for cutting and machining.
* Identification of welding consumables such as electrodes, filler wire, fluxes, shielding and backing gases and any special requirements (e.g. drying) are met.
* Plant and equipment are in a safe condition and adequate for the job.
* Safety permits e.g. hot work permit, gas free permit, enclosed space certificate are
available and valid.
Check * Dimensions, tolerances, preparation, fit-up and alignment are in accordance with the
Approved drawings and standards.
* Tack welds, bridging pieces, clamping and type of backing – if any used are correct.
* Cleanliness of work area is maintained.
* Preheat in accordance with procedure.
NOTE Good inspection prior to welding can eliminate conditions that lead to the formation of defects.
INSPECTION DURING WELDING
Check * The welding process must be monitored.
* Preheat and interpass temperatures must be monitored.
* Interpass cleaning – chipping, grinding, gouging, must be monitored.
* Root and subsequent run sequence.
* Essential variables such as current, voltage, travel speed to be monitored.
* Filler metals, fluxes and shielding gases are correct.
* Welding is in compliance with weld procedure sheet and application standard.
INSPECTION AFTER WELDING
Check * Visual inspection to be carried out to ascertain acceptability of appearance of welds.
* Dimensional accuracy to be ascertained.
* Conformity with drawings and standards requirements.
* Post weld heat treatment, if any, monitored and recorded.
* NDT carried out and reports assessed.
* Assess defects as to either repairing, or application for concession.
* Carry out any necessary repairs.
* Control of distortion
* Repair procedure and welding code should be authorised.
* Defect area should be marked positively and clearly.
* Check when partially removed and fully removed (visual and NDT).
* Re-welding should be monitored.
* Re-inspect completed repair.
Collate all documents and reports. Pass the document package on to a higher authority for final inspection, approval and storage.