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After getting my self stablaized in new company… now i’m evaluating the world around.

We talk about type of welds & weld joints, the talk on welding will be incomplete if we don’t talk about weld defect!

Some weld defects are visible, some are visible with aide & some are invisible and need extra process to reveal them.

Before we go into process of different methods to see those defect, one must first know what are those defects?

Let me show you some defects & with their names

• Spatter

• Incomplete Fusion

• Incomplete Penetration

•  Overlap

• Porosity 

• Undercut 

• Underfill 

Definition

welding noun /ˈwel.dɪŋ/ n [U] the activity of joining metal parts together
(Definition of welding noun from the Cambridge Advanced Learner’s Dictionary)

Welding in industry has huge spectrum! it starts for arc welding, to fusion welding, to Laser and so on and so forth,

Generally, pressure vessel speaking, we use following three type of welding

– SMAW : Shielded Metal Arc Welding
– SAW : Submerged arc welding
– TIG : Tungsten Inert Gas welding
– GMAW : Gas Metal Arc Welding

Other types are
-Atomic Hydrogen Welding(AHW)

-Bare Metal ArcWelding(BMAW)
-Carbon ArcWelding(CAW)
-Electro Gas Welding(EGW)
-Electro Slag Welding(ESW)
-Plasma Arc Welding(PAW)
-Stud Arc Welding(SW)

Lets discuss Generall Welding Process in Brief
SMAW :

As you can see in picture, the arc is created between Parent material and electrode. The oxidation is avoided by the flux coated on electrode. Due to arc the weld metal start melting, and due to high temperature, the flux also get melted, due to density difference, the flux floats over weld pool, and thus by function makes a barrier between atmosphere & weld to avoid any oxidation.
The temperature found in arc is as high as 7000ºC, at which the gas/air get ionized, providing good electrical conductivity in the arc.
The actual transfer of metal from the electrode to the workpiece is in the form of molten globules of different sizes depending on the type of electrode used. Some electrodes produce globules that are so large that they actually shortcircuit the arc for a moment.
Electrodes for manual arc welding (sometimes referred to as stick welding) consist of a rod and a coating material. As a rule, the alloy in the rod will be similar to the material to be welded.

The most common types of electrodes are:
1. The Organic type (electrodes contain large quantities of organic substances such as cellulose)
2. The Rutile type (electrodes contain large quantities of the mineral rutile)
3. The Acid type (electrodes produce an Iron Oxide / Manganese Oxide / Silica type of slag, the metallurgical character which is an acid.)
4. The Basic type (Low Hydrogen)
5. LMA (Low moisture absorption electrode)

TIG Welding:

10 year ago after completing my degree in mechanical engineering , when i joined the industry, as a fresher Fabrication & Pressure vessel both were new to me. I took help of good old hand books from Dennis Moss and Megyesy. Thought they where great tool.. I understood one fact hard way, if you ignore basic, they are no good, as there are big mistakes in Dennis Moss book, which you never come across if you put your mind aside! on other had Megyesy, is too much orientated on ASME VIII Div-1, and will not help much if you want to look beyond horizontal vessel or less complicated vertical vessel.

ASME provide all tools & guidelines to analysis Failure (limits) but fails to help me understand how to implement it in actual practice (Additional loading, Conical head with angle >30º! etc. etc…)

Hence I started this Blog to help understand how to implement old engineering know how in Practical scenario!

currently I’m in phase of switching to a new Industry all together, may be i’ll find more way to implement my know how their & learn new way to optimize things.

Take Care