Welding symbols pdf

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NOTE: "fillet weld" = a triangular shaped weld in a corner. Name three types of joints that use fillet welds? Welding Joint Design & Welding Symbols – Chapter # . Drawing of Weld Symbols. Standards. The British Standard for weld symbols is BS EN When identification of the weld process is required as part of the. WELD SYMBOLS 3, ANSI/AWS SPECIALS. 6. LOCATION OF SYMBOLS 1, BUTT WELDS. 7. LOCATION OF SYMBOLS 2, BUTT WELDS. 8. LOCATION OF.

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Irrata for AWS A, Standard Symbols for Welding, Brazing, and Nondestructive Examination,. The following is the corrected Welding Symbol Chart for AWS. Page 1. Welding Symbols. (ISO ). Page 2. ELEMENTARY WELD SYMBOLS. Square Groove Weld. Single V Groove Weld. Page 3. ELEMENTARY WELD. Skip weld. Key Terms. Spacer. Convex contour. Concave contour. Flush contour. Melt-through. Learning ObjecTive! Be able to interpret AWS welding symbols.

The dimensions of the weld would have to be specified on a drawing note and, as mentioned above, procedure testing would be necessary before the weld size was used in design calculations. Mohan Prasad. The ability to obtain a concave weld profile in the as-welded con- dition depends on the parent metal and the welding process and consumable as well as the expertise of the welder. The tail is optional and needed only for special instructions. Backing strip or backing The term backing strip or backing should not be confused with back weld or backing weld. It is generally the leg length that is specified. The ISO standard requires that all butt welds shall have complete penetration unless there are any contrary indications.

Welding Symbols Quick-Cards - Construction Manuals - Books and Software - Craftsman Book Company

Three intermittent fillet welds with 10 mm leg lengths, the length of each weld 40 mm, the distance between each weld 30mm. Three intermittent fillet welds 6 mm leg lengths, the length of each weld 50mm and the distance between each weld 25mm, welds to be staggered.

Three intermittent fillet welds with 8 mm leg lengths, the length of each weld 25 mm and the distance between each weld 50 mm. Two intermittent fillet welds with 10 mm leg lengths, the length of each weld 20 mm and the distance between each weld 40mm, welds to be staggered.

WIS5 Welding Symbols. Flag for inappropriate content. Related titles. API Welding of pipelines and related facilities. Jump to Page. Search inside document. Single-U butt weld, flat weld profile 10 3. Butt Weld ex: A continuous fillet weld with a 6 mm leg length , toes to be blended smoothly. Joaquim Morais.

John Dare. Baibur Saladin. Abderrahmane Gaouas. Jahzel Callino. Javier Alvarez Vandeputte. Mehman Nasibov. Suresh Rathod.

Pdf welding symbols

Paulo Netz. Morg Actus. More From Niko Gunn. Niko Gunn. The larger number below it signifies 45 degrees, which represents the included angle between the plates. Moving to another part of the overall welding symbol, at the intersection of the reference line and the leader line, two other symbols may be inserted, as shown below: A flagpole indicates a field weld, which simply tells the welder to perform the work on site, rather than in the shop.

The weld-all-around circle, located at the same juncture, means just that. While this symbol is often used in pipe and tubing, a non-circular structural component as shown above right may likewise need welding on all sides. Here are a few other types of instructions you might see on a drawing: A curve located above the weld symbol's face specifies that the finished weld should be either flat, convex or concave.

If you see a straight line, then it's a flat weld - i. As shown on the top right, a V-groove weld symbol with a box above it indicates a backing strip or bar is required for this joint. The strip or bar must be welded onto the back side of the joint before the groove weld is performed. A backing strip or bar is sometimes confused with a "back weld " or a "backing weld".

They are not the same thing as using a backing strip. A back weld is where a second weld is created on the back side of the joint after the primary groove weld is completed.

Conversely, a backing weld is a weld that the welder performs first so it serves the same function as a backing strip. A backing strip is a piece of metal welded on to the bottom of the plates to facilitate a smooth, even weld. Each of these three options are illustrated below using both the tail and the weld symbol to communicate what needs to happen.

As you can see, the only difference between the back and backing welds is when they're performed. The symbols look the same, so both must be specified by name.

In the third symbol, the dimensions and type of steel A for the backing strip are specified. When a welding operation involves a lot of steps, you will sometimes see multiple reference lines on the welding symbol, as shown below: To keep the instructions clear, several reference lines may extend from the leader line at a parallel trajectory. Each line represents a separate operation and is performed in order, beginning with the line closest to the arrow. As you just saw in the case of the backing strip, the forked tail of the welding symbol is used to convey details that aren't part of the normal parameters declared on the reference line.

For instance, the engineer or designer might want the welder to use stick welding i. SMAW , or another welding process. Or there may be other information to convey: Of course, when no special instructions are needed, the tail is omitted from the welding symbol, leaving just the reference line, arrow and leader line. Once you master the basics, you'll be ready to absorb the many other particulars conveyed on shop drawings and blueprints.

Among the most common: Below you'll find the standard chart that's used to communicate information with a welding symbol. You may need to refer to it when there are lots of dimensions listed or uncommon specifications to sort out.

To research welding symbols further, follow the links in the resource box on the upper right of this page. See the link above right. It is appropriate that these instructions should be included as part of a welding symbol.

These are the symbols for a spacer, a back weld or backing weld, melt through and consumable insert. Other supple- mentary symbols in use, and included in the ISO and AWS stan- dards, are those for peripheral welds, field or site welds and backing strips.

Spacer The purpose of a spacer is shown in Fig. The dimensions and material of the spacer are specified in the tail of the reference line or on notes on the drawing. Back weld and backing weld The symbol is used for both a back weld and a backing weld backing run. A backing weld is made before the main weld is made.

In both cases the first operation is indi- cated by the reference line closer to the arrow. The ISO standard requires that all butt welds shall have complete penetration unless there are any contrary indications. In the AWS standard the melt through symbol is used when com- plete joint penetration is required plus so-called visible root rein- forcement.

The height of the root reinforcement may be specified by placing the required dimension to the left of the melt through symbol. The reason for this is difficult to fathom because complete pene- tration is always visible and cannot be improved on by specifying its size. Remedial action would be expensive and unnecessary.

Welding Symbols Quick-Cards

If the size of a penetration bead were to be restricted to a certain dimension for clearance purposes this would be an important requirement for which instructions should be given in notes on the drawing. Consumable insert Consumable inserts are specified in the AWS system by placing the symbol on the side of the reference line opposite the groove weld symbol, as illustrated in Fig. The type of insert is written in the tail of the reference symbol or on a note on the drawing.

In cases where a continuous weld is required, which involves an abrupt change in direction, for example, round an internal or exter- nal corner, the weld all round symbol may be confusing because the extent of welding may not be obvious. This is shown in Fig. The weld all round symbol would not provide as clear an instruction as the symbol for a double fillet weld in the flat, ver- tical and overhead welding positions.

The multiple arrow system is quite clear and it would be permissible to omit the dashed line in the ISO example. There is no significance in the flag being placed either above or below the reference line or whether it points left or right. Backing strip or backing The term backing strip or backing should not be confused with back weld or backing weld. In the AWS standard the material and the dimensions of the backing strip are specified in the tail of the reference line.

In ISO The letter M probably refers to the material and dimensions of the backing strip. The AWS standard also specifies edge preparations. The comprehensive description of a joint specified by the welding symbol in the AWS standard should be used with caution unless it is an established part of a welding procedure.

Otherwise, the pro- cedure might not be in accordance with the standard practice of a particular fabrication shop.

The edge preparation will depend on the welding process, the consumable, the parameters and other details, which may not be known to the design office. In the ISO standard it is stated that, in the absence of any indication to the contrary, butt welds are to have complete penetration see Fig. The AWS standard states that omitting the depth of bevel and weld dimensions from the welding symbol requires complete joint penetration. This is in agreement with the ISO standard.

The AWS standard states that the rule applies to single groove welds and also to double groove welds having symmetrical joint geometry single and double groove welds include V, U, bevel and J welds. Figures 9. For double sided welds, the dashed reference line may be omitted from the ISO symbol, which makes it identical to the AWS symbol. This only applies to symmetrical joint preparations where depths of welds are not included in the welding symbol. In the AWS weld symbol, the number is placed in brackets, as in Fig.

In the AWS system, in which edge preparations can be indicated, the size of the gap between the plates is specified by a number between the sides of the weld symbol. The dimensions of the gap need only be included on one side of the reference line. Groove dimensions In the AWS system full details of the groove dimensions can be speci- fied, for example, bevel angles, root face, root gap, as well as the sizes of the welds on each side of the joint.

Figure 9. This procedure can be specified by the AWS welding symbol. In the example shown in Fig. However, it is permissible to specify the size of the weld on the first side to ensure that it is large enough to limit the depth of back gouging required. The AWS standard describes many examples of combinations of joint edge preparations and weld sizes that can be specified by the welding symbol. In contrast to this, the ISO system limits the infor- mation specified by the welding symbol to the type of weld and its size.

There is a limit to the extent of a welding procedure that can be contained in a welding symbol and it is advisable to supplement this information with additional notes and drawings. This is supported by the AWS standard, which recommends that drawing notes may be used to provide instructions for weld details. This information need not be repeated in welding symbols and the information can include details of edge preparations, weld sizes, etc. The ISO standard follows this practice in principle and recommends that, in order to simplify the drawings, specific instructions should be referred to separately or placed close to the welding symbol.

Sometimes the weld is shorter than the joint length and may consist of inter- mittent welds. In this case the specific lengths of welds and their location may be indicated by dimensions on the right of the weld symbol and on the drawing.

Hatching may also be used to depict graphically the welds shown in Fig. This procedure and alter- native methods are described in detail in AWS A2. However, the ISO standard does include intermittent fillet welds, described in Section 11, and there is no reason why the principle should not be applied to butt welds symbolised in accordance with the ISO standard. Leg z Throat a length thickness In the AWS standard the size of a fillet weld always refers to the leg length, the dimension of which is placed to the left of the weld symbol.

In contrast to the symbol for a groove weld, the fillet weld size is not placed in brackets.

Welding Symbols

In the ISO system, to indicate the size of a fillet weld, the dimen- sion is placed to the left of the symbol, preceded by the letter z or a, depending on whether the leg length or throat thickness is to be speci- fied see Fig. It is generally the leg length that is specified.

The terms describing fillet weld dimensions, actual throat thick- ness and design throat thickness, are shown in Fig. Actual throat thickness Design throat thickness This is followed by the nominal throat thickness preceded by the letter a. Deep penetration of a weld can be achieved by high-current sub- merged arc welding SAW or gas shielded metal arc welding GMAW and by certain types of electrodes.

The depth of penetra- tion must be predetermined by welding procedure testing before the dimension is used for design purposes and is included in the welding symbol. In the AWS standard deep penetration fillet welds are not men- tioned as such and it is not clear how such a weld would be sym- bolised.

The dimensions of the weld would have to be specified on a drawing note and, as mentioned above, procedure testing would be necessary before the weld size was used in design calculations. Double fillet welds In a double fillet weld the dimensions are repeated even if they are identical see Fig. The ISO system uses a closed tail with a reference letter which can refer to a specific instruction such as a note on the drawing see Fig.

The direct instruction or an unambiguous note on the drawing is preferable because the AWS standard places the smaller dimension of an unequal leg length fillet weld first whereas the ISO standard does not refer to unequal leg length fillet welds at all. AWS dimensions are in inches. The AWS system uses a similar device or can include a direct instruction see Fig. If the weld is not continuous and consists of intermittent fillet welds, the weld lengths and the gaps between them are indicated as shown in Fig.

This shows a perspective and plan view as well as a cross-section, the latter indicating the leg length and throat thickness of the weld in the example illustrated. The symbolic representation of weld sizes and lengths, and the gaps between them, is shown in the lower three cross-sections. The nomenclature placed adjacent to the reference lines is shown in Table Table The use of a smaller weld might not be possible because of limi- tations of a particular welding process or because of poor fit-up of the joint.

Small welds of some alloy compositions may crack under conditions of high restraint. Low heat input associated with such welds can increase the risk of the heat affected zone HAZ crack- ing in steel fabrications. These factors confirm the necessity for cooperation between the design office and the fabrication shop before the sizes of the welds are included on a drawing.

Figure It should be noted that the ISO symbol omits the dashed reference line. In the AWS stan- dard, the staggered mode is indicated by the displacement of the fillet weld symbols on the reference line. It is a useful aid to the interpretation of welding symbols. The weld symbol is centred on the reference line see Fig. Other details of the welding symbol shown in Fig.

The strength of a spot weld is related to its size and it is questionable whether mechanical properties should form part of a welding symbol. The purpose of this option and for whom the information is intended are not clear. The nomenclature for both resistance and arc spot welds in the ISO and AWS systems is similar, apart from the placement of the brackets and the figure for the number of welds.

Projection welds In both the ISO and AWS standards the weld symbols for spot and projection welds are identical, but have additional indications. A reference to the size of the projection by a separate sketch is indicated in the tail in the AWS system, as shown in Fig. This figure also shows that the weld symbol in the AWS system is placed above or below the reference line, depending on which member is to be embossed. The only difference in the meaning of the letters is that in the AWS system the letter e indicates the pitch of the welds, i.

The seam welding symbol in the ISO system refers to resistance welding, whereas in the AWS standard, the symbol includes other processes such as arc or electron beam welding. Therefore, in the ISO system the symbol is always placed with its centre on the ref- erence line.

In the AWS system it may be placed above or below the line, depending on whether the weld is made from the arrow side or the other side. This stan- dard should be consulted for authoritative guidance. Studs larger than this can be attached by manual welding using covered electrodes to deposit a fillet weld.

These welds are indicated on a drawing by the fillet weld symbol and the weld all round symbols shown for the ISO example in Fig. Illustration Symbol Stud welds are not specifically mentioned in ISO , but the standard includes a weld symbol for a surface joint as shown in Fig.

This appears to show a stud weld. The application of this symbol on a drawing is not illustrated in ISO but, presumably, the two horizontal lines are placed above and parallel to the refer- ence line. Description Illustration Symbol Surface joint The AWS symbol for a stud weld consists of a circle with a cross in it. The standard specifies that the arrow of the welding symbol shall point clearly to the surface to which the stud is to be welded.

Pdf welding symbols

Therefore the symbol is always placed below the reference line to indicate that the weld is on the arrow side. The AWS standard illus- trates the use of multiple arrow lines pointing to different rows of studs with their locations indicated on the drawing.

The number of studs is placed in brackets below the symbol as shown in Fig. As well as, or in place of, the weld symbol, a stud weld can be indicated by code numbers or letters, described in Section It should be noted that the numbers and letters in the tail do not provide complete information about the welding process, which may be capacitor discharge, arc stud, friction welding, etc.

The surfacing symbol should point clearly to the surface on which the surfacing weld is to be deposited. The thickness of the weld is specified by placing the dimension to the left of the weld symbol, the area to be surfaced is indicated on the drawing see Fig. Multiple layers Multiple layers of surfacing welds may be specified by multiple ref- erence lines, with the thickness of each layer specified by placing its dimension to the left of the weld symbol as shown in Fig.

Figures An example is given in Fig. Apart from process identification, other information, such as codes or standards, may be specified by placing a reference in the tail of the symbol.

It will be appreciated that the provision of such comprehensive information by means of welding symbols could lead to confusion and, in most cases, the information should be detailed on a separate part of the drawing and in a Welding Proce- dure Specification WPS. When information is not required in the tail of the reference line, it is standard practice to omit the tail in the AWS system.

It appears that this practice is also followed in ISO This should not be taken to imply that visual inspection is not required. It is essential and should be obvious that all welded components should be visually inspected as a matter of routine. An application of symbols for NDT is shown in Fig. It should be noted that, in contrast to the arrow for welding symbols, the arrow for NDT always points to the weld to be tested and never refers to a weld on the other side of the joint.

The direction of radiation for radiographic testing may be indi- cated see Fig. The field test symbol Fig. For the clarification of complex drawings the symbols for non- destructive testing can be included on a separate drawing from that showing welding symbols. An NDT procedure sheet would normally be needed to supple- ment the welding symbol, especially if inspection is required during welding to confirm freedom from cracking.

This could involve dye penetrant or magnetic particle inspection between weld passes, a procedure that the welding symbol alone could not indicate. Visual inspection should nearly always be carried out during the welding operation to detect any flaws as well as distortion because it is easier to rectify at an intermediate stage than after welding is completed. The exercises demonstrate the need for cooperation between the designer and fabricator to ensure that the welding pro- cedures are feasible before welding symbols are added to a drawing.

The solutions to the problems begin on page The figures have not been drawn to scale. Exercise 1: Flange ended pipe For the fabrication illustrated in Fig.

The solution is given on page Flush face 30 4 Butt weld to have 6 6 mm fillet removable backing ring. X-ray weld. Single-J welds 10 deep Flange ended pipe dimensions are in millimetres.

Vessel Figure The letters in circles are shown solely for ease of reference in the solution.