Re: [MW:12196] welding procedure for distortion control

The welding procedure adopted does not actually matter for distortion
control in structural welding.The shape of the structure and the heat
input involved during welding is what causes distortion. For example,
if built up sections with thickness greater than 16 mm with lengths
varying from 5M to 10M are to be welded it is always advisable to use
GMAW/FCAW or SAW for both Quality and production. But these being high
heat input processes and the nature of welds being straight lengthy
beads, it is advisable that the sections be placed on LEVEL PLATFORMS,
FIT UP BE CHECKED FOR STRAIGHTNESS,WARPS IN PARENT METALS CAUSED BY GAS
CUTTING. These checks are a must.Thereafter one could clamp down the
sides to be welded to the platform and a staggered sequence of welding
from both sides involving 2 to 4 welders(depending on the weld length)
may be adopted. 2 welders from opposite ends on opposite sides may
start welding simultaneously and weld progression may be towards center
or start from center and proceed towards ends.Alternately staggered
weld areas may be marked on opposite sides and welders may weld
alternate staggered areas on their own sides but from opposite ends.
The idea is to achieve EVEN HEAT DISTRIBUTION. AFTER WELDING, CLAMPS
SHALL NOT BE REMOVED TILL THE WELDED AREAS HAVE COOLED TO AMBIENT.
In case of rolled sections like trestles, purlins etc. where continuous
welding is not involved SMAW can be safely used.Electrode dia should
not be allowed to exceed 3.15mm.
This is a general overview. If some details of structure type is known
I can be more specific.













On Thu, 11 Aug 2011 15:25:03 +0530 wrote
>
Dear friends,



By adopting which welding procedure (SMAW/GMAW/FCAW) we can reduce
distortion in structural welding





Regards,



Purvin Bhatt



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