THE DUTIES OF THE WELDING INSPECTOR

THE DUTIES OF THE WELDING INSPECTOR

Oleh : Bayu Nurwinanto

VISUAL INSPECTION

At any point in the course of welding, i.e. taking, root pass, filler pass or capping pass, but particularly for the root and cap, a detailed inspection may be required. British Standard 5289 :1876 gives guidance on tools and responsibilities together with sketches of typical defects.

The inspector at this point must :

• Observe, idenetify and perhaps. record the features of the weld.
• Decide whether the weld is acceptable in terms of the particular levels which 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.

CODE OF PRACTICE FOR VISUAL INSPECTION

A code of practice for an inspection department could take the form outlined below. It is appreciated that full implementation of the code would be extremely costly and therefore it may be necessary to reduce the amount of inspection to less than is theoretically required.

AIDS OF VISUAL INSPECTION

Illumination :

Good lighting is essential

Inspection lenses :

The magnification should not exceed 2-21/2 diameters. If higher magnification is required use a binocular microscope.

Opitical viewing devices area progressive development from the use of a hand torch and mirror, frequently with the addition of a magnifier and light source.

In order to achieve accessibility probe units are available down to a diameter properties for which are :

• Large field of vision.
• Freedom from distortion of image.
• Accurate preservations of colour values.
• Adequacy of illumination.

VISUAL INSPECTION PRACTICE

The inspector should be familiar with the following :

• All applicable documents.
• Workmanship standards.
• All phases of good workshop practice.
• Tools and measuring devices.

INSPECTION BEFORE WELDING

Before assembly :

Check :

• Application standard.
• Welding procedure sheets.
• Drawings.
• Welder qualifications.
• Material composition.
• Condition of material.
• Type of edge preparation, method and finish.
• Consumables, i.e. type of electrodes, filler wires, fluxes, shielding and backing gases (composition) and special drying requirements for electrodes.
• Welding process.processes.

After assembly :

Check :

• Clearance dimensions, tolerances, type of backing (if any).
• Alignment, tack welds, bridging pieces, etc.
• Cleanlines.
• Preheat.

Note:

Good inspection prior to welding could eliminate conditions that lead to the formation of defects.

INSPECTION DURING WELDING

Check :

• Welding process.
• Preheat and interpass temperatures.
• Inter-run cleaning.
• Joint preparation.
• Filler metals.
• Control of distortion.
• Root and subsequent runs.
• Welding current and voltage.
• Chipping, grinding, gouging.
• Fluxes and shielding gases.
• Compliance with weld procedure sheet and application standard.

REPAIRS

• Mark out area positively and clearly.
• Use a method established and understood by all inspection and repair personnel.
• Check when partially removed (visual and NDT).
• Check when fully removed (visual and NDT).
• Check rewelding.
• Reinspect.