Welding and Fabrication Quality
Welding inspection
Inspection before, during and after welding, so weld quality is controlled at every stage where it can still be influenced.
01What the service involves
Welding inspection follows the sequence of the welding process. Before welding: WPS and welder qualifications, base material and consumables, joint preparation and fit-up, preheat. During welding: parameters, interpass temperature, root and interpass cleaning, back gouging, welding sequence and distortion control. After welding: visual inspection, dimensional checks, post weld heat treatment records, NDT and repairs.
Visual inspection is carried out according to ISO 17637 and evaluated against the quality level specified, usually ISO 5817 level B, C or D for steel, or the acceptance criteria of the applicable code such as AWS D1.1 or ASME.
02Why buyers need it
Most weld defects that reach NDT or service could have been prevented: poor fit-up, missing preheat, damp electrodes, excessive heat input. Inspection during fabrication finds causes, not just consequences.
Visual inspection also decides where NDT is needed and catches surface defects that NDT procedures may not be set up to evaluate.
03Typical applications
- Structural steel and frames
- Pressure vessels and tanks
- Piping and spools
- Machine frames and weldments
- Stainless and duplex fabrication
- Aluminium welded structures
04Methodology
Document check
WPS, WPQR, welder certificates and weld map reviewed for the joints to be welded.
Pre-weld
Materials, consumables, storage, joint geometry, cleanliness and preheat checked.
In-process
Parameters and interpass temperature verified against the WPS; root inspected.
Post-weld
Visual and dimensional inspection to the specified quality level; PWHT records reviewed.
NDT and repairs
NDT extent and results reviewed; repairs controlled and re-tested.
05Applicable standards and references
ISO 17637 covers visual testing of fusion welded joints. ISO 5817 defines quality levels for imperfections in steel welds; ISO 10042 is the equivalent for aluminium. Structural welding in North America commonly follows AWS D1.1, and pressure equipment welding qualification ASME Section IX.
06Deliverables
- Welding inspection report
- Weld map and traceability record
- Visual inspection record with imperfection evaluation
- Parameter verification sheet
- Repair log and NDT summary
07Customer benefits
- Defects prevented at source
- Lower repair and NDT reject rates
- Verified compliance with WPS
- Complete welding traceability
- Confidence in structural integrity
08How QUALITAS TR supports you
QUALITAS TR welding inspection is led by engineers with international welding engineering training. We look at welding as metallurgists: heat input, hydrogen, dilution and microstructure explain most problems.
Frequently asked questions
Which quality level should we specify?
ISO 5817 level C is common for general structural work, level B for fatigue loaded or demanding service, and level D for low demand applications. The design code may prescribe the level. See ISO 5817.
Is visual inspection enough?
Visual inspection is the first and most important test, but it cannot detect internal imperfections. NDT extent should be specified according to the code and service conditions.