Transcript Cooling tube material comparison

Cooling connections in the service
gap
Richard French
The University of Sheffield
Overview
Main topics covered today
• Services Gap Dimensions
• Access requirements for
Welding
• Re-work
Tangential thoughts………..
– Does the TDR lock us into a specific
service gap size
– Access will dictate tube wall size eg
poor access = thicker wall tube
– Purge gas – how to get it to the joint
that we are welding with overpressure
– All applies to rework except
• Tube end preparation for welding
• Cutting out old
• BACK TO ACCESS REQUIREMENTS
Joining and weldability
• 316
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TIG orbital welding limit is 200μm
• Have not tried to reduce further
• Butt welding successful on both 2mm
and 1/8” tube
Diameters are 2.0mm and 1/8” so standard
fittings work without modification
Brazing is ok but untested as not needed to
make this joint as never dissimilar material
Can join this material without much effort or
thinking.
• CP2
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TIG orbital welding limit is 125μm
• Have not tried to reduce further
• Butt welding successful on both
2.275mm and 1/8” tube
Diameters are 2.275mm and 1/8” so
standard fittings work on the 1/8” tube but
are hopeless for the smaller OD.
125μm wall in small OD is not for in-situ
joining or ………..
We need to make the tube preparation very
good but I don’t see this happening yet.
• Its pretty easy once you know how
• We have made thousands of tube welded joints in a range of materials both
commercially, commercial research and have pushed R&D for TIG beyond commercial
requirements to date.
• We evaluate welding machinery for companies using our techniques and equipment
designed in-house.
Christophe Bault – CERN 6/2/14
Service Gap Dimension (z=91mm)
Robert Gabrielczyk - RAL
Detail
• We should not get hung up on the gap
dimensions in Z (photo)
• We should worry about the position of the
tube in relation to the end of stave eg – push
the tube further out to the EC’s to increase
clearance
• NOT WORRIED YET for installation
• WORRIED IF WE NEED TO REWORK in the sense
of a service intervention post installation
Access requirements for welding
• 5.5m cable length from power supply to weld head
• WPS qualified for this length
• Not worried about RF from machine – maybe add a
shielded cable – weld head ok.
• G – Add another 80mm as we need to move the
cassette in and out the head
• C – Add another 10m as we need to add support
collets for in-situ work to suit tube type better
(tube joint alignment and heat sinking)
Need to be realistic and work out what tubes can go
where when held by hand.
Can we use jigs – doubt it.
IM tasked with a measuring system = simple point to
point feeler – check if ok for 3D.
If in doubt we use filler rings to support the tubes. Not
tested at all yet as will be very bespoke
Re-work of connections
Things to consider
• I am not considering re-work of 125um CP2 Ti in-situ
• Here I consider 200um CP2 Ti rework in either 2.5mm OD or 1/8” OD
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We can not weld on a weld – we can but it is very bad practice (annealing)
Cut sections out and replace
Electrical break – capacitance induction or transient voltage
Gas purge must be present during re-work.
• Can we add valves to the system to prevent filling the entire volume?
• Tube ends must be flat and parrallel with excellent surface finish and all oxide
removed, no burrs, no swarf or dust in the bore –
• Debris filtering can be used