There is considerable myth  uncertainty and many misconceptions about welding and in particular  welder approval testing. So called experts like nothing better than to add to the confusion. There is a lot of information to assimilate and understand, but the basics can be explained fairly simply and the myths dispelled, which I will try to do below.

 

I was a mere accountant when I became involved with welding, brought into a family business that drastically needed to widen it’s customer base, being 80% dependant on one large blue chip chemical company which no longer exists! The development of the Morecambe Bay Gas Field held obvious potential and to that end I battled through the tender document to enable our company to become a supplier to Hydrocarbons Great Britain and hopefully win a “Minor Urgent Works” contract to supply pipe work and steel work to the new field in Morecambe Bay.

 

It soon became clear that “welding” was the fundamental issue. Fortunately I could rely on a couple of very good members of staff who really knew their stuff, but I didn’t like not having a clue what they talking about during our pre contract meetings. So I began the road to becoming a welding inspector  which was considerably more interesting than accountancy!!

 

But I still remember what it was like to be completely in the dark without any simple explanation available, so for you here goes.

 

Dear Muppet,

Welding.

 

The joining of two materials where the materials melt and fuse together.

Welding Procedure Specification :

 

Basically how it is proposed the  joining of two bits of metal should be done, detailing all the information the welder will require to carry out the weld.

Welding Procedure Approval Record:

 

A record of what was actually done during the welding together of the sample test piece and a record of all the results of the tests carried out to ensure the weld test piece was satisfactory.

 

(Rule of thumb, when the section  cut out of the test piece is pulled to breaking point, the weld should prove to be stronger than  the parent metal)

Welder Approval Test Record:

 

A record detailing the testing of a welding operative to prove his competence to carry out that type of weld.

Range of approval:

 

Having taken a test, the range of approval is simply what that test covers you to weld. Oviously one test can’t cover all welding and many welders will have to take a number of tests to cover the various types and sizes of material  and the welding process.

Welding Process

 

There are basically four manual welding processes.

Oxy Acetylene:

 

The heat for welding is provided by a torch burning a mixture of oxygen and acetylene and additional weld metal being introduced to the weld by a separate rod of compatible material.

 

Being a very slow process, it has fallen out of general use.

CO2, MIG/MAG, GMAW, Semi Automatic: 

 

The heat is generated by a bare wire of between 0.6mm to 1.6 mm being fed through a torch and arcing onto the parent metal. A shielding gas is also fed through the torch to protect the weld pool from the atmosphere. The gas is generally a mix of CO2 and Argon when the process is correctly called MAG, or Pure Argon when MIG is the correct term. Americans tend to use Helium as an alternative to Argon because of it’s greater availability in the States. Americans refer to the process as GMAW. Semi Automatic was another name given to the process in the earlier days of it’s development but not generally used today.

 

A very fast method of welding and used predominantly in work shop conditions. Not generally suitable for outdoors as gas shield is blown away by wind.

“Stick” welding, MMA, SMAW:

 

A metal rod of between 1.6mm and 5mm of material compatible with the parent metal, is coated with various substances (flux). When the arc is struck the coating burns and generates the gas necessary to provide the shield for the weld pool.

 

Slower than MIG/MAG but not affected by exterior elements other than rain, so ideal for working outside.

TIG:

 

Heat source generated by an ark being struck between the parent metal and a non consumable electrode of Tungsten. Filler material is added separately similar to as in Oxy Acetylene welding. As with MIG/MAG a shielding gas protects the arc from the external atmosphere making it also a process not ideally suited to working outdoors. The gas is generally pure Argon. A slow process but very good when higher degree of precision required.

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