Welding inspection

Examination Procedure
Surface Preparation
* The surface to be examined and the adjacent areas shall be dry and free of dirt, grease, scale welding flux, spatter, oil or any extraneous matter and surface irregularities that could hinder visual inspection.
Inspection before Welding
* Inspector shall ensure that all materials are in suitable condition (Free from damage and contamination) and can be traced to a Test certificate.
* Inspector shall ensure that welding electrodes and consumables are as per the approved WPS. He shall also ensure that their storage conditions are satisfactory.
* QC Engineer/Inspector shall ensure that only approved WPS‘s are used and are available to all welders. He shall also check that welders are qualified as per the project requirement.
Joint Fit-ups shall be checked in accordance with the approved WPS/ Drawings. Tack welds shall be inspected for workmanship standard and to code/WPS. Internal misalignment deviation factor and the inside diameter trimming shall be checked and accepted as per ASME B31.3
Parameters such as Root face, Root gap, Chamfer angle, Tack welds shall be checked with reference to WPS.
* Inspector shall ensure that seam of welded pipe shall be positioned at least 30o apart from horizontal centreline of Butt welding. Also proximity of welds which shall be minimum 3 times the thickness of pipe or 50 mm whichever is higher shall be ensured.
Inspection during Welding
* Inspector has to ascertain each requirement of approved WPS (Welding Procedure Specification) is correctly been taken care of, while performing welding
Pre-Heat and Inter-Pass Temperature shall be monitored as per the approved WPS.
* Inspector shall ensure that the root is visually accepted before further passes are carried out.
* Inspector shall ensure that Welding consumables are in accordance with the approved WPS and being controlled as per procedure. He shall also monitor welding parameters such as current, volts, travel speed.
* Grinding/Inter-run cleaning shall be monitored for workmanship standard and to code/WPS. Weather condition shall be monitored to comply with code.
Inspection After Welding
* Weld visual inspection shall be carried with naked eye or with low power magnifying glass if necessary. Surface inaccessible to direct view may facilitate the use of additional aids like mirrors and boroscopes, slender instruments.
* Weld visual inspection shall be carried out to check dimensions and tolerances, visual indications of discontinuities and features of the weldments to determine if they are within acceptable limits. Defects exceeding acceptance standards shall be repaired. The repaired area shall be re-examined according to the procedure.
* Weld visual inspection is intended to find and mark for repair obvious visual defects such as cracks, surface porosity, dimensional discrepancies, excess concavity or convexity, undercut, misalignment, craters, arc striking spots and any other objectionable visual features. In case of doubt the indications have to be marked and then their importance assessed by further NDT like MPT/DPT.

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