Figure 4–13Pipe weld positions
Plug and Slot Welds
What are plug and slot welds and why are they used?
They join two (or more) parts together by welding them at a point other than their edges. Plug and slot welds are used to secure multilevel parking garage and ship decks from shearing forces. They are particularly useful in sheet metal and auto-body work where welds can be completely concealed by grinding and painting. A hole or slot is made in the work-piece facing the welder and weld is made inside the hole. Filler metal completely fills the hole or slot and penetrates into the lower work-piece(s) securing them together. Plug welds are round and slot welds are elongated and rounded at the ends.
See Figure 4–14.
Figure 4–14Examples of plug and slot welds
Intermittent Welds
What is the difference between a chain intermittent and a staggered intermittent weld?
See Figure 4–15.
Figure 4–15Chain intermittent fillet weld (left) and staggered intermittent fillet weld (right)
Welding Terminology
What terms describe the position of the electrode with respect to the weld?
They are:
•Axis of the weld—an imaginary line drawn parallel to the weld bead through the center of the weld.
•Travel angle—is the smallest angle formed between the electrode and the axis of the weld.
•Work angle—for a T-joint or corner joint, the smallest angle formed by a plane, defined by the electrode (wire) and the axis of the weld, and the work piece.
•Push angle during forehand welding—this is the travel angle during push welding when the electrode (wire) is pointing toward the direction of weld progression.
•Drag angle during backhand welding—this is the travel angle during drag welding when the when the electrode (wire) is pointing away from the direction of weld progression. See Figure 4–16.
Figure 4–16Orientation of the electrode
What is travel speed?
It is the velocity or speed of the electrode (wire) along the travel axis, usually in inches/minute or cm/minute.
What is a tack weld?
Welders place small, initial welds along joints to hold the work pieces in place so the parts remain in alignment when they are welded. Tack welds work hold work firmly in position, but can be broken with a cold chisel in the Event further adjustment is needed. Beginning welders tend to make them too small. One inch is the standard length of a tack weld. A tack should be as strong as the weld itself as it becomes and integral part of the finished weld.
What is a joggle joint?
See Figure 4–17. Joggle joints are used where a strong joint and flat surface is needed to join two pieces of sheet metal or light plate. There are hand tools available to put the joggle into sheet metal. They are useful whenever a finished surface concealing the weld is needed and where a butt joint would not work with thin sheet metal.
Figure 4–17Joggle weld joint preparation
What is the difference between a stringer bead and a weave bead?
In a stringer bead the path of the electrode is straight, with no appreciable side to side movement, and parallel to the axis of the weld, while a weave bead has a side-to-side motion which makes the weld bead wider (and the heat-affected zone larger) than that made with a stringer bead.
What is padding or overlaying and what is it used for?
Padding is when weld filler metal is applied to a surface to build up a plate or shaft, to make a plate thicker, or to increase the diameter of a shaft. It is used either to restore a dimension to a worn part or to apply an extra hard wear surface. See Figure 4–18A shaft, bar or pipe and 4–18B is resurfacing a plate.
Figure 4–18AResurfacing on shaft, bar or pipe axial and circumferential welds
Figure 4–18BResurfacing on a plate
What is the purpose of surfacing welds?
Surfacing, also called hard surfacing, is the application of extra hard weld metal (padding) to surfaces subject to severe wear and abrasion. The teeth, buckets, and blades of earth moving equipment are often surfaced, as are the interior chutes of rock crushers. SMAW, GTAW, FCAW, and GMAW processes can all perform surfacing given the proper electrode metal composition.
What does the term boxing mean?
Boxing is when a fillet weld is continued around a corner. Normally a fillet weld is made from one abrupt end of the joint to the other abrupt end of the joint. See Figure 4–19.
Figure 4–19Boxing weld
Welding on Thick Plates
What is a root pass weld and where is it used?
A root pass uses weld filler metal to close the root space between the weld faces. It is especially helpful in welding pipe and thick plates where only one side of the weld is accessible and no backing material is used.
What is a back weld?
A back weld is applied after a groove weld is completed. The back weld is made to insure full penetration through the material being joined. Before we apply the back weld we must grind or gouge into the bottom of the groove weld until we reach sound weld metal then we may apply the back weld to the bottom of the groove weld. See Figure 4-20.
Figure 4–20-21Back weld and backing weld
What is a backing weld?