Piping welding symbols pdf

This weld is simple and therefore cheap to apply but could be seriously deficient in performance. Unless access is available to both sides of the joint, it will be impossible to weld it.

This weld normally requires edge preparation on a horizontal member, and therefore is more complex and expensive. However, it may be essential for certain service conditions.

It can be seen from the previous examples that major problems will arise unless welded joints are carefully specified by the design office. The situation is particularly critical where, for example, work is placed with a subcontractor and the instructions need to be espe- cially precise.

In the majority of cases, symbolic representation can be used to cut down the time needed to complete the drawing and improve clarity. These symbols are placed on a horizontal reference line. This line is attached to an arrow line which points to the location of the weld see Fig.

In the ISO system there are two parallel reference lines, one solid and one dashed. In the AWS system a solid reference line is used. Apart from weld symbols placed on the reference line, additional information can be supplied adjacent to the tail which is generally omitted when not required. The arrow line can point in any direction as shown in Fig. This is so that it can locate welds in any welding position, for example flat or overhead. The arrow line is never drawn horizon- tally because this would make it appear to be a continuation of the reference line, which is always horizontal.

It is conventional practice to refer to the opposite sides of a welded joint as the arrow side and the other side see Fig. Other side Arrow side Arrow side Other side a b 2. In the AWS system the weld symbol for a weld on the arrow side is placed below the line and for a weld on the other side the symbol is placed above the line.

In the ISO system the dashed line can be drawn above or below the solid line but the symbols on the solid line always refer to the arrow side of the joint. Symbols on the dashed line indicate a weld on the other side. It is recommended that the solid line is always drawn above the dashed line as standard practice.

If a weld is made on both sides, as in a double fillet weld, the weld symbol is placed on both sides of the reference line or lines, in which case, in the ISO system, the dashed line can be omitted. Figure 2. Without using weld symbols, Fig. If the section thicknesses of parts are small compared with their overall size, as in box girders, the welds are often too small to be drawn to scale and to be reproduced accurately, as illustrated in Fig.

In order to simplify drawings as much as possible, the ISO standard recommends that, where appropriate, full details of edge preparations should be shown separately. This is also in accordance with AWS recommendations. Figure 3. This weld will be limited to a maximum section thickness depending on the welding process used.

If a backing strip is used, the section thickness can be increased considerably. Guidance on edge preparations is included in BS EN and ISO , in which the range of thickness recommended for this type of weld is 3—8 mm. Without a backing strip, a maximum section thickness of 4 mm is recommended with a gap equal to the thickness. With a backing strip, a gap of 6—8 mm is recommended.

Dimensions of edge prepa- rations are not included with weld symbols in ISO but these can be included with AWS symbols. This can make a drawing complex and, in some cases, may lead to confusion. This edge preparation is generally used when it is only possible to prepare one edge of adjoining sections. This weld is used to restrict the quantity of weld metal required in sections greater than 16 mm thick when it is only possible to prepare one edge of adjoining sections.

The AWS term is a more accurate description of this weld, which is an edge weld, described in Section 4. In this weld the edges are melted down to form a low strength sealing weld. In the AWS system, if full pen- etration is required, the welding symbol includes the melt-through symbol shown in Fig.

Figures 3. They are illustrated in Fig. Dimensions of a broad root face are specified in ISO A root face of 2—3 mm is specified for section thicknesses of 5—40 mm, whereas for a single-V butt weld Fig. As stated previously, when ISO is used, the dimensions of the edge preparations are not included as part of the welding symbol and should be given as part of the WPS.

With the AWS system, the depth of the groove can be specified by a number on the left hand side of the weld symbol. This dimension, subtracted from the section thickness, will indicate the size of the root face Fig. Weld cross-section AWS 1 2 1 7 3 2 8 8 3. Figure 4. Unless otherwise indicated, the leg lengths are normally equal. The ISO and AWS symbols are fairly similar and are drawn above and below the reference line respectively, both indicating a weld on the arrow side. However, there is no possibility of confusion because the edge weld can only be deposited on one side.

This is not a weld in its own right, as this symbol is not used on its own. It is deposited on the opposite side of the joint to the main weld, so both sides must be accessible. The AWS standard includes symbols for flare-V-groove and flare- bevel-groove welds.

A flare-V-groove weld, shown in Fig. A flare-bevel-groove weld, shown in Fig. The commonest application for these welds is in the welding of reinforcing bars. The size of the hole should be restricted to avoid excessive distortion and unnec- essary consumption of filler metal. AWS symbols would be similarly placed on the reference line for resistance welds and below the line for arc welds.

These symbols are shown in Fig. Figure 5. The upper illustration shows a resistance spot weld or projection weld requiring access from both sides. The lower illustration shows an arc spot weld made from one side of the joint. The reference line is on one side of the symbol. The upper illustration shows a resistance seam weld requiring access from both sides of the joint. The lower illustration shows an arc seam weld made from one side of the joint.

Arc spot and arc seam welding processes are rarely used and, by common usage, spot and seam welding mean resistance welding. In this symbol, the arrow line points to the surface to be coated with weld metal. ISO does not explain how to indicate the extent of the surface coating which is essential information. AWS A2. ISO includes two symbols representing a steep flanked single-V butt weld and a steep flanked single-bevel butt weld.

The welds have a backing strip. These symbols are not included in the AWS standard and are not really necessary because the welds are, in fact, single-V and single- bevel butt welds.

They can be indicated as such by including the symbol for a backing strip shown in Fig. Both symbols in Fig. The lines vary slightly in length. This difference is pointless because, as in the case of the fillet weld symbol, the symbols would be placed with the lines directly on the reference line. There are no examples of the application of these symbols in ISO For the single-V butt weld shown in Fig. The arrow can point to the weld in a plan view, as shown in Fig. Figure 6. The AWS standard specifies that when only one edge of a joint is to be prepared, as in a single-bevel or J-groove weld, the arrow line should be drawn with a break more accurately described as a sharp bend as shown in Fig.

The arrow line need not be bent if it is obvious which edge of the joint is to be bevelled or if there is no preference as to which edge is to be prepared. In the ISO system the symbol for a weld on the arrow side is placed on the continuous line and the symbol for a weld on the other side is placed on the dashed line. In the AWS system the symbol for a weld on the arrow side is placed below the single continuous line and the symbol for a weld on the other side is placed above the line.

This is illustrated in Fig. Figure 7. The shape of the weld would not normally be shown on an engineering drawing. The two welds are on different joints, i.

Therefore, two separate arrows are required to indicate two single fillet welds. In Fig. The fillet weld symbol is always drawn with the upright leg on the left.

For the joint in Fig. This practice should be used with caution to avoid a drawing with a minimum of weld symbols and a multitude of arrow lines criss- crossing the drawing. In other cases, only one of the standards uses a symbol for a particular requirement. All the symbols in Fig. Their application is shown in the following pages. Contours of welds Figure 8. The AWS standard states that welds to be made with a flush, flat, convex or concave contour, without the use of mechanical finishing, shall be specified by adding the flush or flat, convex or concave symbol to the welding symbol.

This practice seems slightly pedantic and it is questionable to what extent it is carried out. Figure 8. In the ISO system it is likely that the Welding Procedure Specifi- cation WPS would contain instructions on post-weld finishing treatment required, such as grinding or machining. In contrast to this, in the AWS system the symbol indicates that the surface finish is to be achieved in the as-welded condition.

In the AWS system the method of post-weld finishing is shown by the capital letters M and G, indicating machining and grinding. All welds are normally deposited with a slightly convex profile to provide the minimum required throat thickness without excess weld metal.

This symbol, without further instructions, could cause confusion in a welding shop because it would encourage a welder to deposit excess weld metal, which would create potential problems and additional costs.

The location of the convex weld symbol is shown in Fig. It is worth noting that AWS D1. This excess metal is sometimes wrongly called reinforcement. This is incorrect because in only very rare cases would it increase the static strength of a joint and in many cases it would reduce the fatigue strength. Its location is shown in Fig.

A concave weld profile reduces stress concentration at the toes of a fillet weld and thus gives a slight improvement in the fatigue strength. 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.

In mechanised welding processes it is sometimes possible to produce a concave weld profile by using suitable welding parameter settings. Toes blended smoothly The ISO standard includes a symbol for weld toes to be blended smoothly.

It can be used to inform the welder that the weld toes are to be ground in order to remove any small slag intrusions that exist at the toes of welds made by manual metal arc MMA or shielded metal arc SMAW welding. The maximum depth of intrusions is usually 0. The purpose of weld toe grinding is to increase the fatigue strength of the welded joint. This is important because slag intru- sions can act as initiation sites for fatigue cracks.

The process of weld toe grinding for fatigue strength improvement is highly skilled and requires training. It will be evident from the foregoing descriptions that, if a par- ticular weld profile is desired, it may not be possible to convey all the essential requirements by means of welding symbols.

In this case separate, detailed instructions should be given in a Welding Proce- dure Specification WPS or on a note on the drawing.

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. Instead, weld even stitches across side one. The Z-shaped symbol with a line passing through its center displays the effect of a 7 in a mirror. It shows two 7s equally proportioned but flipped, making a Z. Likewise, the staggered intermittent weld is equal on both sides of a feature but flipped so that the welds sit in different places but with the same spaces.

Most symbols are based on the cross-section view of the joints they represent. Be sure to download the PDF version of this welding symbol guide to refer to on the job and ensure your welds are correct according to the drawing.

Cameron grew up in Allentown, Pennsylvania, a once-proud steel town on the Lehigh River, where he got a taste of TIG welding in his high school shop class. His interests include scuba diving, sculpture, and kayaking. Water Welders is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you.

Learn more. PDF Form: Do you need to study on the run? Welding Symbols Test There are also various theoretical tests you may be required to take during your career, including your qualification and certification tests. The Base Platform This symbol is a simple platform for displaying the characteristics and surrounding details for your welds. It has three parts: The arrow line: points to the general location of the weld.

The reference line: this is where the details are placed about the type of weld and the specific location. The tail: this is where the complementary details, separate from the specifics, are placed.

This includes welding standards, material types, and the welding process required. The Two Drawing Systems There are two systems the base welding symbol comes in, and they are each interpreted differently. Base system B Base system B is recognized by the absence of dashes below the reference line. Base Butt Welding Symbol Chart As the name states, these joints are distinguished by their butting up to each other end to end. Single-Sided Butt Welds These joints are only welded on one side and are easily recognized as single-sided by their symbol.

Square butt This joint has no weld prep. Double-Sided Butt Joints These welds are precisely the same as single-sided butt joints, except both sides are prepped and welded, as shown in the below weld symbols chart. Double-sided bevel butt One plate has no weld prep, keeping its corners square. Other Base Symbols Butt welds and fillet welds are the most common types of stitch. Fillet This symbol has a right-angled triangle, since the most common fillet joint is between two plates at a right angle to each other.

Plug One plate with a hole sits on top of another plain plate. Resistance spot Two plates are fused together by creating heat from electrical resistance between the plates with a resistance spot welder. Resistance seam This is like a resistance spot weld, only the electrical resistance creates a long seam weld rather than a single spot. Supplementary Symbols These symbols are added to the base symbols to clarify the type of weld required. Flush finish This weld symbol signifies that the weld needs to be machined or ground back flush to the level of the rest of the plate.

Convex The convex finish of a weld curves outwards like a balloon away from the weld, just as its symbol displays. Consumable insert Inside a weld prep, a consumable plug is inserted at the bottom where there is space between the two sections. Weld entirely around This symbol circles the corner of the base platform to show that the section being pointed at needs welding the whole way around it, like a circle. In this book, you will find a lot of useful information. It contains a joining method chart, master chart of welding and joining processes, joint types, roots, grooves, welding position diagrams, test positions, bead types, explanations of weld parts and sizes, various weld profiles, weld discontinuities, current polarities, various welding nomenclature, different crack types, flame types… You name it, it has it.

You should definitely consider getting it and reading it. You are unlikely to constantly apply this information but having it available on your shelf for easy access is invaluable in the welding trade.

This is a standard that shows certain systems that allow you to understand welding, brazing, and nondestructive examination requirements. This is a serious book that is dedicated to symbols only.

This publication is created to help in communication between the design, fabrication, and inspection teams. If all parties involved know the extent of the symbols as their job position requires them to and the symbols are well designated then the production process should flow properly.

This book has been evolving throughout the years since its first release in It is currently in its seventh edition which speaks volumes of how many times it was revised and improved upon. You are unlikely to find a better in-depth manual for standard symbols. A highly recommended book. If you are in doubt about understanding the groove weld, the V groove weld, the field weld, or anything else, you can consult the welding symbol chart that provides some of the commonly used symbols and welding specifications for help.

A good welder is not complete without knowing at least the basic welding symbols. One can start without knowing them but in order to become a professional welder, you should have a basic understanding of them.

Adam Mason. TIG Welders. MIG Welders. SMAW Welders. Plasma Cutters. Flux Core Welders. Multi Process Welders. Welding Symbols PDF. How to MIG Weld. How to TIG Weld. Welding Joints. Best Welding Schools. Welding Stainless. Welding Helmets. Change The Battery. Underwater Welding Helmet. Welding Gloves. Lens Shade Guide. Disclaimer Weldingpros. By Adam Mason. In: Welding Last Updated on: November 10, The Arrow 2.

The Reference Line 3. Fillet Example — Length of Weld Defined 3. Weld Symbol Below Reference Line 2. Weld Symbol Above Reference Line 3. Welding Symbols Quick Chart Conclusion. The table presents some of the most commonly used welding symbols.

Fillet — The most used weld. Groove — Second most used. It usually involves preparing the edge pieces to form one of the groove weld shapes like V, bevel, U, J, Flare V, Flare bevel or no preparation at all with square edges to form a square groove. Flange or edge welds. Seam welds — They are made using high heat input and are made in linear form. Spot welding — Done similarly to the seam except that these welds are done in a singular spot.

These are some of the supplemental weld symbols. The article below covers others as well and in more detail. The backing weld is deposited before the actual weld in the groove.

Something like giving the weld a good back. Melt-thru — Indicates that the root of the weld needs to be reinforced.

Surfacing — Specifies the welds that are made over the entire surface of the piece. Backing bar — Designates the backing bar to be used on the back of the weld. If it has R in it, it should be removed after welding. Spacer — This symbol indicates the type and the dimension of the spacer that is inserted between the welded pieces. Weld all around — It signals that the weld is to be made over the entire circumference. Contour — These symbols designate the final weld end product contour.

Fillet Example — Length of Weld Defined. V Groove Numbering Example. Weld Symbol Below Reference Line. Weld Symbol Above Reference Line. Above And Below Reference Line. Fillet Weld T Joint Example. Plug Welds Symbol Example.

Slot Welds Symbol Example. No Flag — Made in Shop. It also includes graphic representations of the systems included. Conclusion A good welder is not complete without knowing at least the basic welding symbols. Adam Mason Welder by trade for a decade and more. Now also a web designer and a blog owner. Doing product reviews and writing blogs about welding trade and perks and minuses of being a welder.

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