Whenever there is a discussion for the design of a welding project between an engineer and a welder it always comes down to the blueprints. Now, what’s blueprint made of? The answer’s Welding Symbols.
Understanding Welding Symbols
So, here’s the solution to all those hours of talking with your engineer and understanding exactly what he wants solely from the blueprint.
The very first thing that you have to know to understand welding blueprints is the reference line. The reference line is just a straight horizontal line having two sides the arrow side and the other.
Reference Arrow or Leader
Reference arrow is on the arrow side as you can see from the figure. It points toward a welding joint. Usually referred to as the reference arrow or the leader.
Let me show you, how to indicate a basic filler weld. The arrow or the leader as we know is always pointed towards a welding joint. Now, if you want to put a weld to where the arrow is pointing, you’ll have to put the welding symbol on the arrow side.
Now, what if you wanted to put an arrow on the other side.
Now if you want to put on weld on both sides.
Size of Welding
To denote the size of welding on the blueprint you’ll have to write it on the left side of the welding symbol.
Notes and Specification
When you’ll have to put notes and specifications about the weld you will have to put it on the tail i.e. on the other end of the reference line. An example of specifications is mentioning the electrode.
This picture tells that the welding has to be done with 6010 electrodes.
If you need your welder to join two pieces of the weld on the spot rather than in the shop then a flag symbol as shown in the diagram below make it clear.
Weld All Around
This symbol indicates that you’ll have to join two pieces of the project. And the welding has to be done all around the joint, not in any specific positions.
Let show you what I mean by leg sizes.
Now how do you put this information in a welding symbol? Here’s how you do it.
At times you will not need to weld the entire length of the joint. But do it in a certain distance. Here’s how the engineers will tell this to you.
Here the black portions are the welding puddles. What the welding symbol means is that each puddle will be 1 inch in length and the gap between them will be 3 inches.
Here you can see a metal sheet one on top of the other. The top one has a hole in it and it is welded to the one in the bottom.
Welding Joints Symbol
Now I’ll be showing you different types of welding joints and their symbols.
Square Grove Weld Symbol
Single V Groove Weld Symbol
Single Bevel Grove Weld Symbol
Single V Grove Weld with Broad Root Face Symbol
Single Bevel Grove Weld with Broad Root Face Symbol
Single U Grove Weld Symbol
Single J Grove Weld Symbol
Backing Weld Symbol
Spot Weld Symbol
Seam Welding Symbol
Edge Welding Symbol
Many designers require a definite contour for their products. Here’s a couple of symbols indicating definite type of contour.
This contour requires tooling to get the required result. There’s no particular example for this. It’ll be described by the designer in the tail or somewhere else.
After a proper weld, the end result of the weld bead is normally convex contour. But at times a few industries such as food and petroleum require more height. This is a measure taken for corrosion.
This is done by back gouging the weld beams.
Now let’s talk about the whole blueprint and what are the things you will be found in there.
- This one’s the arrow or the leader line which points towards the welding spot.
- This means that you will have to weld all around i.e. the spot from which you will start welding is where you will end it.
- If this is found in the blueprint then that particular weld has to be done in the field, not in the shop.
- L stands for length and represents the length of the weld in intermittent welding.
- P stands for a pitch which represents the distance between welds.
- R stands for root opening, this represents the distance that has to be maintained between the pieces in Grove welding.
- “A” stands for angle and represents the angle at which the pieces have to be welded in case of grove welding.
- This indicates the effective throat, you can understand what effective throat is from the picture below.
- F stands for finishing, this and the symbol indicates the type of contour the designers want.
- The side of this arrow is pointing is the arrow side
- This is where the weld symbols are to be placed.
- T stands for the tail and any notes or specifications which could not be placed in the blueprint is said here.
- The number of spots to be welded in spot welding or in any other cases is shown here.
- This is just to point out that the everything will remain the same with respect to the leader line no matter the orientation of welding.
- This is known as the depth of preparation and indicates the depth up to which welding has to do in cases such as plug and grove welding.
By this time, you have covered all the basics of welding symbols. You know almost all the welding joints and their symbol and can relate among the two of them.
So, you’ll never have to see the dissatisfactory face of the engineers and do the thing over and over just because you couldn’t understand what he was trying to say.
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