Welding quality and performance
Welding is one of the principle activities in modern fabrication, ship building and offshore industry. The performance of these industries regarding product quality, delivery schedule and productivity depends upon structural design, production planning, welding technology adopted and distortion control measures implemented during fabrication. The quality of welding depends on the following parameters:
1. Skill of Welder
2. Welding parameters
3. Shielding medium and
4. Working environment
5. Work layout
6. Plate edge preparation
7. Fit-up and alignment
8. Protection from wild winds during-on-site welding
9. Dimensional accuracy
10. Correct processes and procedures
11. Suitable distortion control procedures in place Selection of Welding Process and Filler Metal:
The welding process and filler metal should be so selected that the weld deposit will be compatible with the base metal and will have mechanical properties similar to or better than the base metal.
Comparison of high energy density welding processes and TIG welding for plate thickness 6 mm.
Parameter |
TIG |
Plasma |
Laser |
EB |
Power input to workpiece |
2 kW |
4 kW |
4 kW |
5 kW |
Total power used |
3 kW |
6 kW |
50 kW |
6 kW |
Traverse Speed |
2 mm/s |
5.7 mm/s |
16 mm/s |
40 mm/s |
Positional |
Good |
Good |
Yes |
Requires |
Welding |
penetration |
penetration |
Requires optics to move the beam |
mechanism to move the beam |
Distortion |
Nominal |
Nominal |
Small |
Minimum |
Shrinkage |
Significant in V-shaped weld |
significant in V-shaped weld |
Minimum |
Minimum |
Special |
Normal |
Normal |
Safety interlock |
Vacuum |
Process |
Light |
Light |
against misplaced |
chambers, |
Requirements |
Screening |
Screening |
beam reflection |
X-ray Screening |
Surface |
Underside |
Underside |
Very fine |
Ruffled swarf |
Geometry |
Protrusion |
protrusion |
ripples |
on back face |