Common welding symbols and their meaning
When welds are indicated on engineering and fabrication drawings, a cryptic set of symbols is used as a kind of shorthand to describe the type of weld, its size, and other processing and finishing information. Here we present the common symbols and their meanings. The complete set of symbols is specified in a standard published by the American National Standards Institute (ANSI) and the American Welding Society (AWS): ANSI/AWS A2.4, Symbols for Welding and Nondestructive Testing.
The structure of the weld symbol.
The horizontal line, called the reference line, is the anchor to which all other weld symbols are attached. The instructions for making the weld are aligned along the reference line. An arrow connects the reference line with theSolder connection. In the example above, the arrow grows from the right end of the reference line and points down and to the right, but many other combinations are allowed.
There are often two sides of the joint indicated by the arrow, and therefore two potential locations for a weld. For example, when joining two steel plates into a T, the weld can be made on either side of the shank of the T.
The welding symbol distinguishes between the two sides of a joint using the arrow and the spaces above and below the guide. The side of the joint that the arrow points to is called (quite prosaically) the arrow side, and is welded according to the instructions below the reference line. The other side of the joint is called (even more prosaically) the other side, and its welding is carried out according to the instructions on the reference line.The rule that below the line equals the side of the arrow and above the line equals the other side applies regardless of the direction of the arrow.. The flag that grows at the junction of the reference line and the arrow is present when a weld must be made during the assembly of the structure in the field. An unflagged welding symbol indicates that welding must be done in the shop. On older drawings, a field weld may be indicated by a black circle at the junction of the arrow and the reference line.
The open circle at the intersection of the arrow/reference line is present when the weld must go around the joint, as in the example below.
The end of the weld symbol is the place for additional information about the weld. It may contain a reference to the welding process, the electrode, a detailed drawing, or other information that aids in the execution of the weld and does not have its own place in the symbol.
Types of welds and their symbols.
allwelding positionit has its own base symbol, which is usually placed near the center of the reference line (and above or below depending on which side of the joint it is on). The symbol is a small drawing that can be interpreted primarily as a simplified weld cross section. In the following descriptions, the symbol is shown both on the arrow side and on the other side.
Socket welds and groove welds
OWeld(pronounced "fill-it") is used to make lap joints, corner joints, and T-joints. As the symbol indicates, the fillet weld has a roughly triangular cross section, although its shape is not always a right or isosceles triangle. . triangle. The weld metal is deposited in a corner formed by the mating of the two members and penetrates and fuses with the base metal to form the joint. (Note: For graphical clarity, the following drawings do not show weld metal penetration. Note, however, that the degree of penetration is important in determining weld quality.)
The right side of the triangle is always drawn on the left side of the symbol, regardless of the orientation of the weld itself. The leg size is written to the left of the weld symbol. If the two solder legs are to be the same size, only one dimension is specified; If the weld is uneven leg (much less common than isosceles weld), both measurements are given and the drawing indicates which leg is longer.
The length of the weld is indicated to the right of the symbol.
If the length is not specified, the weld must be placed between the specified dimension lines (if specified) or between points where an abrupt change in weld direction would occur (as in the example above at the end of plates).
For tack welds, the length of each weld section and the space between welds are separated by a hyphen (first length, second space) and placed to the right of the fillet symbol.
Please note that the distanceTomás, is not the free distance between the welds, but the center-to-center (or end-to-end) distance.
Ogroove weldCommonly used to make end-to-end joints, although it is also commonly used for corner joints, T-joints, and joints between curved and flat pieces. As the variety of seam symbols suggests, there are many ways to create a seam, the differences mainly depending on the geometry of the parts to be joined and the preparation of their edges. Weld metal is deposited in the groove and penetrates and fuses with the base metal to form the joint. (Note: For graphical clarity, the drawings below generally do not show weld metal penetration. Note, however, that the degree of penetration is important in determining weld quality.)
The different types of groove welds are:
The groove is created by a tight fit or slight parting of the edges. The extent of the gap, if any, is indicated on the weld symbol.
The edges of both pieces are either single or double beveled to create the groove. The angle of the V is indicated on the weld symbol, as is the root gap (if any).
If the V depth is not full thickness, or half thickness in the case of a double V, the depth is indicated to the left of the weld symbol.
If the weld penetration is greater than the groove depth, the groove deptheffective neckis given in parentheses after the depth of the V.
Bevel Groove Welds
The edge of one of the pieces is beveled and the other is left square. The vertical line of the chamfer symbol is always drawn on the left side, regardless of the orientation of the weld itself, the arrow points to the part to be chamfered. This additional meaning is emphasized by a cut in the arrow line. (It is not necessary to break if the designer has no preference as to which part is edge-treated, or if the part to be edge-treated should be obvious to a qualified welder.) The angle and depth of edge treatment, effective fillet, and root clearance are described using the methods discussed in the V-groove section.
The edges of both parts are treated concavely. Edge treatment depth, effective fillet, and root spacing are described using the methods described in the V-grooves section.
The edge of one of the pieces is treated as concave and the other is left square. It is to the U-weld what the groove weld is to the V-weld. As with the groove weld, the vertical line is always drawn on the left side and the arrow (possibly with a cut) points to the left side. part that receives the weld edge treatment. Edge treatment depth, effective fillet, and root spacing are described using the methods described in the V-grooves section.
Commonly used to connect two rounded or curved parts. The desired depth of the weld itself is given to the left of the symbol, with the depth of the weld in parentheses.
Commonly used to join a round or curved part to a flat part. As with Flare-V, the depth of the groove formed by the two curved surfaces and the desired depth of the weld itself are given to the left of the symbol, with the depth of the weld in parentheses. The vertical line of the symbol is always drawn on the left side, regardless of the orientation of the weld itself.
Common auxiliary symbols used with grooved welds are themeltmisupport rodsymbols Both symbols indicate that full penetration of the joint must be made with a grooved weld on one side. When fusing, the root at the back of the weld must be reinforced with weld metal. The rebar height, if critical, is given to the left of the fusion symbol, which is placed on the reference line of the base weld symbol.
When a reinforcing bar is used to achieve full penetration weld, its symbol is placed on the reference line of the basic weld symbol. If the bar is removed after the weld is complete, an "R" is placed inside the support bar icon. The support bar symbol has the same shape as the groove or plug weld symbol, but the context should always clarify the intent of the symbol.
Socket and socket welds
socket weldsmisplit seamsused to join overlapping members, one of which has holes (round for socket welds, oblong for groove welds). Weld metal is deposited in the holes and penetrates and fuses with the base metal of the two members to form the joint. (Note: For graphical clarity, the drawings below do not show weld metal penetration. Note, however, that the degree of penetration is important in determining weld quality.) For socket welds, the diameter of each plug is shown to the left of the and the connector-to-connector distance (distance) is shown to the right. For groove welds, the width of each groove is indicated to the left of the symbol, the length and spacing (separated by a hyphen) to the right of the symbol, and a detailed drawing is referenced at the end. The number of sockets or grooves is shown in parentheses above or below the weld symbol. Labels on the arrow side and on the other side indicate which part contains the hole or holes. If the hole is not completely filled with weld metal, the depth to which it must be filled is specified in the weld symbol.
For more information, see ANSI/AWS A2.4, Welding and Nondestructive Testing Symbols.