Selecting Electrodes

B-16	OPERATION	B-16

In some instances a back-up strip may be used and plates may be gapped 1/8” (3.2mm) or more, as shown in figure (b).

	(b)	Scrap steel back-up strip
(a)	(b)	(c)

Three ways to prepare plates where complete penetration is necessary.

On sections where only a sealed joint is required and strength is not important, the joint may be welded after slightly veeing out the seam as shown in figure (d) below.

(d)(e)

Single and double beads, with and without beveling for tight, partial strength joints.

Which electrode is best for the particular job . . . how do you use it? These are important questions because the cost, quality, and appearance of your work depends on proper electrode selection and applica- tion. MILD STEEL ELECTRODES may be classified into the following groups:

Out-of-Position Group (AWS E6011)

High-Speed Group (AWS E6013)

This group includes electrodes which have a moder- ately forceful arc and deposit rates between those of the out-of-position and high-deposit electrodes.

They are primarily general purpose production elec- trodes especially for downhill fillets and laps or short and irregular welds that change direction or position. They are also widely used in maintenance and recom- mended for sheet metal fillet and lap welds. Motion “D” (see drawing) is generally used for vertical-up welding, but motions “A” and “B” are also suitable.

Low Hydrogen Group (AWS E7018)

These electrodes are generally called “low hydrogen”. The name comes from the fact that their coating contains little hydrogen in either moisture or chemical form. Low hydrogen electrodes offer these benefits: outstanding crack resistance, lowest porosity on sulphur bearing steels, and X-ray quality deposit capa- bility. Thus, they are the first choice when welding “problem” steels. E7018 can be used in all positions, with Motion “C” (below) recommended for the first pass on vertical-up welds. NEVER use a whipping technique or a long arc with these electrodes. ALWAYS fill craters by drawing electrode away slowly. ALWAYS keep these electrodes dry. Electrodes, when not used within a few hours after a container is opened, must be stored in heated cabinets.

This group includes electrodes which have a snappy, deep penetrating arc and fast freezing deposits.

These electrodes are used for general purpose, all- position fabrication and repair welding. They are also the best choice for pipe welding and sheet metal butt, corner, and edge welds. They can be used for repair work when dirt, grease, plating or paint cannot be completely cleaned from the steel. These electrodes are typically used with motions “A” and “B” (see draw- ing) for the first pass on vertical-up welds.

Motions

START F

B G

SIDE

AVIEW

BULLDOG™ 140

OPERATION