1. Teknologi Dan Rekayasa
PRINCIPLES OF WELDING

2. WELDING TERMS AND WELDING SYMBOLS
Objective :
After studying this unit the students can be able to :
1. identify the welding terms
2. explain the welding symbols.
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3. Welding Terms
Welding is most often used in the form of a butt weld or a fillet weld, so we shall use these to show the most common welding terms.
Fillet weld : two pieces of plate are joined together at right angles.
Butt weld : two pieces of plate are joined together at 180°.
Slot weld : two flat plates are joined with their edges overlapping.
Plug weld : similar to a slot weld but uses a round hole of at least twice the thickness of metal being welded.

4. Welding Terms Parent metal : the metal on which the weld is deposited.
Weld metal : the metal deposited by the electrode.
Plate preparation : the way in which the plates are prepared before welding.
Root gap : the gap between the vee prepared plates of a butt weld.
Root face : a flat area filed or ground on the sharp edge of the vee preparation.
Weld face : the outside face of the weld deposit.

5. Welding Terms 35° 90° Root face Root gap Weld face Reinforcement
Penetration
Throat thickness
Parent metal
Root gap
Weld metal

6. Welding Terms Convex Mitre weld Fusion face Concave Parent metal
Throat thickness
Nominal throat thickness
Convex
Fusion zone
Leg length
Concave
Fusion face
Mitre weld
Weld metal
Reinforcement
Parent metal

7. Welding Terms
Penetration : In a butt weld the weld metal that flows through the root gap. In a fillet weld the weld metal that fuses into the corner where the two plates join is penetration.
Fusion face : where the weld metal joins the parent metal.
Leg length : the length of the fusion face in a fillet weld.
Throat thickness : the actual distance from the root to the face of the weld.
Reinforcement : in a butt weld is that metal on the face of the weld that is higher that the surrounding parent metal.

8. WELDING SYMBOLS
A series of symbols have been standardized by the American Welding Society.
Welding symbols uses in fabricating the required product and indicate to the welder the kind of weld, the location of weld and the size of the weld.
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9. Base of Weld Symbol
The main foundation of the weld symbol is a reference line with an arrow at one end.
The other data reflecting various characteristic of the weld by abbreviations, figure, and other line arrangements placed around the reference line.
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10. WELDING SYMBOLS A = angle F = finishing symbol L = length of weld
S L – P A F R
A = angle
F = finishing symbol
L = length of weld
P = pitch of welds
N = number of spots weld
R = root
S = size
T = tail
= field weld symbol
= weld all around symbol
= contour symbol
= reference line
= basic weld symbol
Fig. 1. Standard location of element of welding symbol
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11. Designating types of welds
The important factor in understanding weld symbol is recognizing the representations used for different types of welds. These welds are used on five basic kind of joints : butt, corner, lap, tee and edge.
Welds are classified : fillet, plug or slot, spot, seam, and groove.
Groove welds are further divided according to the particular shape of the groove joint.
Each type of weld has its own specific symbol. For example, a fillet weld is designated by a right triangle, and a plug weld by a rectangle.
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12. WELDING SYMBOLS Fig. 2. Common types of weld Joints 1. Butt joint
3. Lap joint
2. Corner joint
4. Tee joint
5. Edge joint
Fig. 2. Common types of weld Joints
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13. Location of Welds
Another requirement in understanding weld symbols is the method which is used to specify on what side of a joint a weld is to be made.
A weld is said to be either on the arrow or other side of a joint. The arrow side is the surface that is in direct line of vision, while the other side is the opposite surface of the joint.
Weld location is designated by running the arrowhead of the reference line to the joint. The direction of the arrow is not important, that is, it can run on either side of joint and extend upward or downward.
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14. Location of Welds
If the weld is to be made on the arrow side, the appropriate weld symbol is placed below the reference line. If the weld is to be located on the other side of the joint, the weld symbol is placed above the reference line.
When both sides of the joint are to be welded, the same weld symbol appears above and below the reference line.
The only exception to this practice of indicating weld location is in seam and spot welding. With seam or spot welds, the arrowhead is simply run to the centerline of the weld seam and the appropriate weld symbol placed above, below or astride the reference line.
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15. Location of Welds
Information on weld symbols is place to read from left to right along the reference line in accordance with the usual conventions of drafting.
Fillet, bevel and J-groove, flare-bevel groove, and corner-flange weld symbols are shown with the perpendicular leg always to the left.
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16. Basic arc and gas weld symbols Supplementary Symbols
Weld Symbols (AWS)
Fillet
Plug or Slot
Spot or projection
Seam
Back or Backing
Melt Thru
Surfacing
Flange Edge
Flange Corner
Groove
Square V
Bevel U J
Flare V
Flare bevel
Basic arc and gas weld symbols
Weld all around
Field Weld
Contour
Flush
Convex
Concave
Supplementary Symbols
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17. Weld Symbols (AWS) Fig. 3. Side of a joint OTHER SIDE ARROW SIDE
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18. Fig. 4. Location of fillet weld
Weld Symbols (AWS)
OTHER SIDE
ARROW SIDE
BOTH SIDE
Fig. 4. Location of fillet weld
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19. Combined Weld Symbols
In the fabrication of product, there are occasions when more than one type of weld is to be made on a joint. Thus a joint may require both a fillet and double bevel groove weld.

20. Size of Welds
There are several types of groove welds. Their size as shown in Fig. 5.
The width of a fillet weld is shown to the left of the weld symbol and is expressed in fractions, decimals or millimeters.
The other size of a fillet weld as shown in Fig. 6
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21. Size of Welds Fig. 5. Size of groove weld 35° 1 70° 10 3 ARROW SIDE
OTHER SIDE
35° 3 5 10
25°
BOTH SIDE
35°
25° 3 10 5
Fig. 5. Size of groove weld
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22. Size of Welds Fig. 6. Size of fillet weld 10 100 100 SINGLE 10 10 100
DOUBLE 10
100
Fig. 6. Size of fillet weld

23. THE END
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