Operation Manual

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A7 TIG Orbital System 300© Kemppi Oy 2016 1615
OPERATING MANUAL
5.3 Common weld defects: identification and prevention
Problem Possible solution
High frequency but
no weld current
Check for broken electrode or ground cable in the weld head,
handle, or in the cable.
Defects in butt welds
Lack of penetration
with workpiece in
horizontal (5G) or
vertical (2G) positions
• Insucient current
• Rotation speed too high
• Contaminated gas, insucient gas or wrong gas
• Arc gap too great, wrong tungsten tip conguration or
Contaminated/worn tungsten electrode
• Gas ow too high
• Arc not on the joint
• Tube wall dimensional variation
• End of tube not square
• Too much gas on I.D. or no I.D. purge
• Tubes not cleaned
ID location • Increase rotation delay or increase Level 1 amps
• Increase weld current or decrease weld head speed
• Use next weld level 2 to increase amps
• Downslope starting too soon; increase time at last level or use
Start position to initiate downslope.
Concavity (suck-
back) or excessive
penetration
All ID locations
• Weld current too high
• Rotation speed too low
• Tubes not tightly butted together
• Tubes ends not square
• ID purge gas pressure too high; create larger gas exit hole
Over-penetration General
Over penetration is most common through the 12 o’ clock position
in horizontal (5G) welding.
• Increase rotation speed
• Decrease weld current
• Contaminated or improper gas
• Gas ow too high
• Tungsten arc gap may have changed or tungsten conguration
has changed
• Weld head not in calibration
• Tubes not tightly butted
• Tube ends not square
ID location
• Rotation delay period too long, too much weld current or
rotation to low
• Increase speed or decrease current.
• Current too high in weld level or may need to change to another
level with reduction in current.
Porosity or improper
gas coverage
• Contaminated gas or improper gas
• Oil, dirt or other contaminant on tube ID/OD.
• Hole in gas line aspirating air
• Pre-purge/post-purge time too short
• Poor welding tube alloy
• Gas ow rate ID or OD too low