Figure 1-24 Weld backing plate
Runoff Plates
This is a made of the same material as the work being joined. The plate is tack welded to the joint at the start and/or end of the groove joint. The runoff plate contains a groove like the pieces being joined. It prevents the discontinuities caused by beginning and ending the welding process. See Figure 1-25.
Figure 1-25 Runoff plate or tab
Multiple Pass Technique
Use multiple passes of parallel weld beads when you are faced with making a large weld but the electrode deposition is much smaller than the weld width. See Figure 1-26.
Figure 1-26 Multiple passes to join thick material
What are some common welding positions?
They are determined by the position of the axis of the weld with respect to the horizontal and whether they are made on plate or pipe. See Figure 1-27.
Figure 1-27 Groove weld (upper) and fillet weld positions (lower)
Welding Positions for Pipe
See Figure 1-28. Note the difference between welding positions A , and C: In position A, (1G) the pipe may be rotated about its longitudinal axis to provide access to any part of the weld joint allowing the welder the opportunity to weld the entire pipe in the flat (1G) position; in position C, (5G) the pipe is fixed and cannot rotate forcing the welder to weld upward or downward vertically, flat on the top and overhead on the bottom; position B is pipe in a vertical position and welded on the horizontal plane; pipe in D is on a 45° angle and all positions (flat, horizontal, vertical, and overhead) are welded when pipe is in this position; the final position is pipe at a 45° with a restrictor in place (the restrictor allows the welder to weld only from one side of the restrictor) making this the most difficult of all welding positions.
Figure 1-28 Pipe weld positions
Slag Removal
Remove slag between weld passes or the remaining slag will form inclusions within the weld metal and weaken it. Slag is usually removed with a slag hammer and wire brush angle grinders or pneumatic peening tools may also be used. Sometimes a wire wheel is used. Pipe welding, grinders and power wheels are used between each welding pass to assure a slag-free surface on which to begin the next pass.
GENERAL TOOLS, MATERIALS AND SAFETY EQUIPMENT
Each welding process requires specialized equipment to do the job. But welding, whether you use it for hobby purposes or to make home repairs, requires a number of common hand and power tools. Many of these tools you may already have in your toolbox, others you may need to purchase. One thing is certain, you will need a wide assortment of clamps to hold the work in position—both to keep the work steady while you weld and to reduce weld-induced distortion. The metals you will be working with all have different characteristics and react differently under the intense heat of the welding torch. This chapter will look at some of the properties of those metals. And, finally, you will also require specialized safety equipment.
WHAT HAND TOOLS ARE USED IN WELDING?
WHAT POWER TOOLS ARE USED IN WELDING?
WHAT TYPES OF CLAMPS ARE USED IN WELDING?
WHAT ARE THE MOST COMMON STEEL PRODUCTS USED IN WELDING?
WHAT ARE SOME BASIC SAFETY REQUIREMENTS?
What hand tools are used in welding?
A welder removes slag after a welding pass
You may already own many of these tools because they are commonly used for general carpentry and household repair. Some tools that you should have to facilitate your welding include:
•Builder’s and torpedo levels—Use the larger builder’s level whenever possible; it is more accurate and measures over a longer span; use the torpedo level wherever the builder’s level won’t fit.
•Framing, carpenter’s, cabinet maker’s, and combination squares—Use the largest square that fits the work. The combination square is convenient for layout of 45° corner cuts and parallel lines.
•Cold chisel and ball peen hammer—Handy for breaking tack welds when they must be repositioned; also useful for removing material between a series of drilled holes (chain drilling).
•Center Punch—Marks hole centers and cutting lines.
•Compass and dividers—For scribing circles or stepping off a series of equal intervals.
•Files—For bringing an oversized part down to exact dimension or removing a hazardous razor/burr edge.
•Hack saw—For slow, but accurate metal cutting.
•Tape measures—16- and 24-foot tapes are the most convenient sizes. Useful for measuring on curved surfaces too.
•Precision steel rules—Available in lengths from 6 to 72 inches (150 to 1000 mm).
•Protractor—For finding angles.
•Trammel points—These points fit on and adjust along a wood or metal beam and scribe circles or arcs with 20- to 40-foot (6 to 12 m) diameters. See Figure 1-2.
Figure 2-1 Here is a selection of typical hand tools used in welding, including an assortment of hammers, wrenches, screwdrivers, and pliers (top), as well different types of squares, such as carpenter’s squares, speed squares, and combination squares. You will find uses for both builder’s levels and smaller torpedo levels (below)
Figure 2-2 This page contains an assortment of common hand tools, including hammers, pliers, wrenches, and levels. At left are trammel points for scribing large circles
Metal Marking Tools
There are a variety of tools used to mark metal layout lines. They include
•Chalk