principles of welding

Teknologi Dan Rekayasa

PRINCIPLES OF WELDING

Teknologi dan Rekayasa

WELDING TERMS AND WELDING SYMBOLS

Objective :After studying this unit the students can be able to :1. identify the welding terms2. explain the welding symbols.

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.

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.

Welding Terms

Root face Root

gap

90°

35° 35°

Weld faceReinforcement

Penetration

Throat thickness

Parent metal Root gap

Weld metal

Welding Terms

Throat thickness

Nominal throat thickness

Convex

Fusion zoneLeg length

ConcaveFusion face

Mitre weld

Weld metal

Reinforcement

Parent metal

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.


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.


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.

( N )

T S L – P

A F

R

A = angle F = finishing symbolL = length of weldP = pitch of weldsN = number of spots weldR = root S = sizeT = tail = field weld symbol = weld all around symbol = contour symbol = reference line = basic weld symbol


WELDING SYMBOLS

Fig. 1. Standard location of element of welding symbol


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.

Fig. 2. Common types of weld Joints


WELDING SYMBOLS

1. Butt joint 3. Lap joint

2. Corner joint 4. Tee joint 5. Edge joint


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.


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.


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.


Weld Symbols (AWS)Fillet Plug or

SlotSpot or projection Seam Back or

BackingMelt Thru Surfacing Flange

EdgeFlange Corner

Groove

Square V Bevel U J Flare V

Flare bevel

Weld all around

Field Weld

Contour

Flush Convex Concave

Basic arc and gas weld symbols

Supplementary Symbols

Weld Symbols (AWS)


Fig. 3. Side of a joint

OTHER SIDE

ARROW SIDE

ARROW SIDE

OTHER SIDE

OTHER SIDE

ARROW SIDE

OTHER SIDE

ARROW SIDE

OTHER SIDE

ARROW SIDE

Weld Symbols (AWS)


Fig. 4. Location of fillet weld

OTHER SIDE

BOTH SIDE

ARROW SIDE

Combined Weld SymbolsCombined 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.


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


Size of WeldsSize of Welds70°

3

10

Fig. 5. Size of groove weld

35°

1

105

35°

25°

3

10 370°OTHER SIDE

35°1

ARROW SIDE

35°3

5

1025°

BOTH SIDE

10

100 10010

SINGLE

Fig. 6. Size of fillet weld

Size of WeldsSize of Welds

DOUBLE

10

10010

10

100

principles of welding

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