keyhole tig(gtaw) advantages in titanium pressure vessel longitudinal seam welding
Customer welded 9.5mm thichness,2.5m length titanium pressure vessel by traditional GTAW ,the following is thire wleding process details ：
Previous Process & Setup
The edges of the joint were bevelled 22.5degrees (45 included angle) with a gap 2.4mm and no landing.
The weld joint was cleaned with carbide, followed by a flapper wheel 50mm beyond the weld joint on both face and backside of the weld joint, then wiped with acetone to clean any residue.
The backside of the weld was ‘bagged’ with tape and foil, covering at least 50mm on either side of the joint, and flooded with argon shielding gas.
The top face of the weld joint was taped off to keep it clean and retain the back-purge gas.
The weld was performed with a manual TIG torch using a trailing cup using argon for primary and secondary shielding.
The 9mm joint was welded in 4 passes using 2.4mm and 3.2mm
welding wire.
Travel speeds for the welding were 75 to 100 mm/min.
After using our keyhole tig(gtaw)automatic welding system
Joint preparation is square butt for entire thickness, no bevel and no gap.
The joint is cleaned in the same way as previously done, carbide followed by a flapper wheel out to 50mm beyond the weld joint then wiped with acetone to clean any residue.
Purging is done using argon, the backside of the weld is ‘bagged’, covering at least 50mm on either side of the joint. A pre-weld ‘sealing pass’ is performed with a small amount of wire to seal the joint to ensure high quality purging.
The weld is performed in a single, full penetration pass.
Travel speed is 300 to 320mm/min.
0.9mm diameter wire is added at a feed rate of 500mm/min.