Welding consumables

A-l (b) Weld metal deposits shall be impact tested per para. GR-2.1.3 if design min. temp. < -29°C (-20°F), except as provided in Notes (2) and (3), and except as follows for materials listed for Curves C and D of Fig. GR-2.1.2(b)A, where corresponding welding consumables are qualified by impact testing at the design minimum temperature or lower in accordance with the applicable AWS specification, additional testing is not required. 

The weld overlay was analyzed and found to be a plain carbon steel, with a hardness of Rockwell 80 HRB, consistent with a low-strength welding consumable (e.g., E7018). The... 

In many cases, a small decrease in the corrosion resistance of weldments is tolerable. When the environment is particularly severe for the alloy being used, the weld may be attacked preferentially. This condition can be exaggerated by the area effects of the more noble base metal compared to the small weld zone. An alternate approach for field welding is fo selecf a higher alloy welding consumable so fhe weld deposif is more noble than the base metal. Preferential attack can also occur in the heat-affected zone of the base metal. This is typical of weldments made in standard type 304 where the carbon content will lead to chromium carbide precipitation. Of course, this condition cannot be avoided by using a different filler mefal and the only remedy is a postweld anneal. 

AWS Standards. American Welding Society produces standards on various aspects of welding and has developed a series of 31 standards on welding consumables, solders and brazes. They contain specifications on composition of the filler metal, composition of the completed weld deposit (when applicable), minimum strength of the completed weld, dimensional requirements of a weld, impact properties (when applicable) and radiographic standards, for example, specification A5.1 Carbon Steel Covered Electrodes includes the following types ... 

Specify welding consumables, brazes and solders per AWS designation. 

Control over the hydrogen potential of welding consumables once they are received from the manufacturer depends on the conditions under which they are stored and used. Storerooms should therefore be dry and warm to minimise moisture pick-up by electrodes and fluxes, and care should be taken to see that the welding operation does not put oil, grease, moisture, etc, on to the welding wire or moisture into electrode coatings and fluxes. 

The determination of the hydrogen potential of welding consumables by encapsulation... 

A welding test conducted before beginning a major fabrication to confirm that the selected welding procedure is safe. The test wehl is designed so that material, welding consumables, joint geometry, restraint, fit-up, etc, closely resemble the details of the actual fabrication. After welding, the joints are sectioned and examined for cracks. 

Using weld consumables that make the weld metal more noble than the base material. 

In pipe systems on the platform, the most severe corrosion attacks have been found between the wellhead and the first-stage separator, where water is precipitated, and where pressure, temperature as well as flow velocity are highest [8.29]. To a great extent, the attacks are localized in and at welds, in pipe joints, bends, and at places with reduced pipe diameter. (In many cases the attacks at welds could have been avoided by proper selection of welding consumables.) When the water content exceeds a critical level, the attacks become more severe. This is probably the reason for increased corrosion when the producing wells get older (the content of water increases with time due to water injection). 

Due to the composition of the weld consumables used, the SAWs had a higher level of impurity Cu than the other materials. In the USA, Cu had been recognised as an impurity element promoting greater irradiation susceptibility in steels and welds exposed in PWRs at higher irradiation temperatures and doses. In the UK, Fisher, Harbottle and Aldridge showed that the process of Cu precipitate nucleation and growth, which was... 

X Factor Similar to J factor but only applies to weld consumables. 

The construction contractors concerned, which provide welding equipment, welding consumables, welders and supervision... 

Verification that material both sides of the welds and weld consumables correspond to specified requirements and are traceable to test and analysis certificates... 

Differential weld corrosion has been found to be particularly problematic in oil and gas flow lines. Even minor differences in composition and microstructure have been found to result in severe preferential galvanic dissolution of pipeline weldments. The selection of welding consumables and welding procedures to minimize this risk is critical. However, even with these precautions, operating conditions can induce severe preferential weld corrosion. On-line corrosion monitoring programs have been conducted in oil and gas pipelines to identify these operating conditions and to optimize the application of corrosion inhibitors to control the problem. 

C — /2% Mo welding consumables and those having more than 1% Ni should not be used for welding carbon-manganese steel. 

The corrosion behavior of carbon steel weldments is dependent on a number of factors. Consideration must be given to the compositional effects of the base metal and welding consumable and to the different welding processes used. Because carbon steels undergo metallurgical transformations across the weld and HAZ, micro-slructures and morphologies become important. 

Once duplex base metal and welding consumables have been selected, it is then necessary to select joint designs and weld parameters that will produce welding heat inputs and cooling rates so as to produce a favorable balance of austenite and ferrite in the weld and HAZ. 

WTIA Technical Note 3, 1994. Care and Conditioning of Arc Welding Consumables. WTIA TN-3-94. Welding Technology Institute of AustraUa, Silverwater, NSW. 

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