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Tungsten inert gas welding is a constant current drooping arc process. It is also known as TIG, gas tungsten arc welding - GTAW, wolfram inert gas - WIG, and under the trade names of argon arc and heli arc.

Lack of fusion/penetration cause by : Too large an electrode for weld preparation. Incorrect angle of electrode for weld preparation. Current too low. Travel speed too high etc

Too short an arc length will cause irregular piling of the weld metal. The ripples will be irregular in height and width.

Positional welding (other than flat) often relies on arc force and surface tension effect; therefore the welding position may affect the mechanical properties of the weld and the likelihood of defects.

Manual metal arc (MMA) welding, also known as shielded metal arc welding (SMAW), stick, and electric arc welding is a constant current drooping arc process.

The identification of covered electrodes in EN 499 is as follows:Covered electrode, strength, Toughness, Chemical composition, covering, efficiency, positional capability, low hydrogen potential

A general purpose electrode, which gives the best appearance and is easy to use. Drying - easy. 1000C for one hour and stored at ambient for shelf life.

Welding consumables are: Electrodes. Wire (lengths or rolls). Fluxes. Gases. Each consumable is critical in respect to: Specification / supplier. Condition. Treatment (if any).

Before a welding repair is carried out the need for repair must be carefully considered. If a component or structure contains defects of a known size, whether these are fabrication or service defects,

A special dye is applied to the surface of the article to be tested. A suitable time interval allows it to soak into any surface defects. The surface is then freed from surplus dye and the dye in the crack revealed by either

The defect may be in a single run fillet weld requiring only a small amount of metal to be removed or it may be a large crack extending deep into parent metal.

The repair of defects that occur during welding ranges from simple welding operations to improve weld profile to extensive metal removal and subsequent welding to rectify extensive cracking.

Gamma rays, similar to X-rays but of shorter wavelength, are emitted continuously from the isotope. It cannot be 'switched off' so when not in use, it is kept in a heavy storage container that absorbs radiation. They pass through the work to be inspected.

The work is magnetized either by passing a current through it, or through a coil surrounding it. Defects on or near the surface disrupt the magnetic field (unless they are parallel to it)

Non Destructive Testing, Ultrasonic Testing : Type of operation:Manual or mechanized. Equipment:Main unit comprising pulse generator, display oscilloscope, probe (chosen to suit work).

Porosity. Is the result of gas being entrapped within the solidifying weld metal. Porosity will be present in a weld if the welding technique, materials used or condition of the weld joint promotes gas formation.

A crack is a linear discontinuity produced by fracture. Cracks may be longitudinal, transverse, edge, crater, centreline, fusion zone, underbead, weld metal or parent metal.

Occurs in the HAZ due to the precipitation of chromium carbides. In the 5500C - 8500C range, the chromium leaches out of the grain and reacts with the carbon to form chromium carbides, due to the chromium having a greater affinity for carbon.

Welding is usually regarded as a joining process in which the work pieces are in atomic contact often with a filler metal with broadly similar properties. Hence soldering and brazing are excluded but both solid state and fusion welding are included.

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