How to Read Welding Blueprints

Architects and drafters commonly include welding instructions in their designs.  This ensures that the welder will know exactly how the architect wanted the welding to be performed.  These instructions often include which type of weld to be used, the size of the weld, how many similar welds need to be performed, and in specific instructions they will tell the welder which joint the weld should be made.  If you are just staring out in the welding world, odds are at some point in your career you will be required to read welding blueprints in order to complete your job.

Weld-symbols
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The first thing you will need to do is to look at the back of the welding symbol.  It will contain either a symbol or an abbreviation used to describe the type of welding process that must be used.  This word or abbreviation will typically be located between two lines that enclose the reference line.  Once you have located the symbol you should then follow it into the reference line.  The reference line will inform you where the welding should be done.  Sometimes the symbol will end at the reference line while other will go beyond it and may even branch out into multiple arrows which are used to indicate the need for multiple welding tasks to be performed. 

Sometimes in welding blueprints the reference line may include a break.  A break in the reference line indicates that a joint preparation must be performed.  The appearance of a break shows the type of preparation that must be done prior to welding.  The next thing you should look for at the end of the reference line is the arrow.  Once you have located the arrow you should look for symbols on the arrow.  If there are any symbols on the arrow in the same side of the reference line this is an indication that an arrow side weld must be performed.  An arrow side weld refers to performing a weld on the side that the arrow is pointing to.  If the symbol is located above the arrow, the weld should be performed on the opposite side.  If you happen to notice a symbol on the arrow side and another break on top of it, this means that the weld must be performed on both sides of the item described in the draft.

Reading welding blueprints can be a very complicated and confusing task.  But after you have gained some experience in reading welding blueprints it will be second nature to you.  As with all welding techniques, with some time and practice you will soon master them.  Reading welding blueprints is no different, as complicated and confusing as they may seem in the beginning; the longer you read them the easier it will be to understand.  If, for any reason you find that you don’t understand the requirements of the welding blueprint you can always ask another welder.  There is no shame in not knowing what a symbol means; it could be more costly to perform the wrong type of weld in the wrong area.  Welding blueprints contain a lot of required information and you should never rush when reading them.  To ensure that the proper weld is performed take your time when reading a welding blueprint.

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