Weld Inspection and NDT Safety

Weld inspection and non-destructive testing verify the quality of welded joints without damaging the completed weld.
NDT methods include ultrasonic testing, magnetic particle inspection, dye penetrant testing, and radiographic examination.
Radiographic testing uses gamma radiation or X-rays to examine welds — this creates an ionising radiation exposure hazard.
Exclusion zones must surround the radiation source during all radiographic testing operations on the construction site.
Only certified NDT technicians holding valid PCN or equivalent qualifications may carry out non-destructive examination.
Magnetic particle inspection uses strong magnetic fields and iron filings to detect surface and near-surface defects.
Dye penetrant testing uses chemical sprays that require COSHH assessment and appropriate PPE during application.
Ultrasonic testing is the safest NDT method, using sound waves that present no radiation or chemical hazard.
Weld inspection results must be recorded and retained as permanent quality records for the structural documentation.
Defective welds identified by NDT must be repaired and re-inspected before the structure can be accepted.

Radiation exposure	Radiographic testing emits ionising radiation that causes cancer — exclusion zones protect everyone nearby from exposure.
Structural integrity	NDT confirms welds will hold the loads they are designed for — undetected defects cause catastrophic structural failure.
Competent examination	Only certified NDT technicians can reliably interpret test results — unqualified interpretation misses critical defects.

Do

Don't

Establish exclusion zones during all radiographic testing operations on site.
Ensure only PCN-certified NDT technicians carry out non-destructive examinations.
Follow the COSHH assessment when using dye penetrant chemicals during inspection.
Record all weld inspection and NDT results as permanent quality documentation.
Repair and re-inspect defective welds before accepting the structural connection.
Brief nearby workers on the radiographic testing schedule and exclusion zones.
Wear appropriate PPE when handling magnetic particle or dye penetrant materials.
Use ultrasonic testing as the preferred method where it provides adequate detection.
Ensure radiation sources are stored securely and transported by authorised persons.
Present welds for inspection at the hold points defined in the inspection plan.

DON'T enter exclusion zones during radiographic testing — radiation exposure causes cancer.
DON'T allow unqualified persons to carry out or interpret NDT examinations.
DON'T use dye penetrant chemicals without reading the COSHH assessment and wearing PPE.
DON'T accept welds without documented inspection and NDT results in the records.
DON'T cover or load welded joints that have failed NDT without repair and re-test.
DON'T ignore radiographic testing schedules — you must know when zones are active.
DON'T handle magnetic or chemical testing materials without the correct protective equipment.
DON'T dismiss ultrasonic testing — it is effective, safe, and avoids radiation hazards.
DON'T leave radiation sources unsecured — they must be locked in approved storage.
DON'T bypass hold points — welds must be inspected before the structure progresses.

See also: Welding Safety Awareness (Comprehensive) | Quality Hold and Witness Points

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