Welding filler metals Standards

Applicable Standards. The following standards are applicable to specifying welding filler metals ... 

A-3.1.1 Welding With the Addition of Filler Metal [See Para. GR-3.2.5(b)(2)]. The ends to be welded shall be prepared by machining or facing to provide a square end that meets the requirements of ANSI standards for tubing. The weld joints shall be properly cleaned within... 

The recommended materials of construction can be welded using standard methods and matched filler metal weld wire. 

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 ... 

See Figure 2-4. AWS publishes Filler Metal Comparison Charts, a book that compares trade names of welding products with standard designations. 

Comments and suggestions for the improvement of this standard are welcome. They should be sent to the Secretary, AWS A5 Committee on Filler Metals and Allied Materials, American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126. 

Corrosion failures of welds occur in spite of the fact that the appropriate base metal and filler metal have been selected, industry codes and standards have been followed, and welds have been deposited that possess full penetration and have the proper shape and contour. It is sometimes difficult to determine why welds corrode however, one or more of the following factors are often implicated ... 

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. 

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