Multiprocess (CC/CV)

1. Welding Processes Power Supply

Commercial welders are aware that the selection of a welding process to be used depends on and is determined by the characteristics of the joint, as well as the materials used including the design of the joint, the materials’ shape and thickness. The good commercial welder also knows that he has to consider the production requirements as well, including the rate and the quality.

After the welding process has been determined by the arc welder, that the proper power supply and welding equipment are chosen. In other words, it is the welding process that is the primary factor in the selection of the power supply that is to be used. In this article and in the ones that follow will be presented a guide concerning the power supplies for the welding processes that have been especially used in the past ten years.

The welding processes have once been considered as special, yet today they could be found in all spheres of m

Repair welding is that type of welding that multiprocess welders perform when they want to make a certain item safe again and bring it back to its satisfactory operating condition. Sometimes the experienced arc welder can allow himself the so called alterations.

The alterations are the changes that the commercial welder can do to the pressure vessel, which will change its original design. These alterations are usually done when the manufacturer has presented a certificate authorization issued and validated by ASME. The alterations that the stick welder makes should always comply with the code section to which the original boiler or the pressure vessel was constructed.

The commercial welders do need to get a written repair procedure for making the alterations or doing the repair work. If the welder will perform an alteration, then a record has to be made and the alteration work has to be approved. The alteration records are usually filed with the jurisdictional agency

Many commercial welders today are employed in the process of maintenance and repair welding rather than in any other sphere of the welding industry. In other words there is a serious need of multiprocess welders who can perform various repair services and maintenance jobs. In fact, it should be mentioned here that the earliest usage of the welding processes was to repair different items.

As arc welders know, the success of a repair depends on the preparation that is done before the actual doing of the work. The good stick welder takes all the factors into consideration before starting the welding process.

In general, the multiprocess welder makes a detailed analysis, checking the repairs made and the service life of the part that is repaired. The stick welders can use this detailed method to analyze the welding job that has to be done. The four main points that the multiprocess welder has to take into consideration include:

- Making a very detailed examination

Multiprocess welders are trained to operate with different steels and under different conditions and circumstances. In several consecutive articles we will present the welding process when the MIG welders, TIG welders, Arc welders and Stick welders perform welds with high-strength steels. The first situation to be covered here is the welding of medium-carbon harden steels with low-alloy.

The steels that are best known to the commercial welders include AISI 4140 and AISI 4130 steels, as well as the steels of higher strength AISI 4340 and AMS 6434. MIG welders know that by processing these steels with heat, they obtain high strength which improves their toughness and ductility. It should be said, as arc welders confirm, that the temperatures used affect the strength levels in those steels. The carbon used by the Stick welders here is of medium and low range, however the amount is sufficient to secure the desired strength. The impurities in these welds are minimal, as the multiprocess