Design for Leak Testing

Robert Limpenny, IEng, MInstNDT.

4th Vacuum Symposium – Ricoh Arena Coventry

All Aspects of Leak Detection

17th October 2013

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 2

INTRODUCTION.

THE FOCUS OF DESIGN IS OFTEN DIRECTED MORE TOWARDS THE

PROCESS, OR EXPERIMENT TO BE PERFORMED WITHIN THE VACUUM,

WITH POSSIBLY LESS CONSIDERATION AT TIMES GIVEN TO THE DESIGN

OF THE VACUUM ENVELOPE, VACUUM GENERATING PLANT OR BY WHAT

MEANS THE VACUUM INTEGRITY MAY BE CHECKED, I.E. LEAK TESTED.

THIS PRESENTATION IS AIMED AT AVOIDING THE NEED FOR HINDSIGHT

IN YOUR VACUUM SYSTEM BUILD, IN FACT I HOPE THAT IT WILL

DEMONSTRATE THAT IT MAKES HINDSIGHT REDUNDANT!

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 3

OUTLINE

DESIGN AND MATERIAL FAULTS.

OVERCOMING THE LACK OF LEAK TESTING FEATURES.

DESIGN AHEAD FOR TESTING.

DESIGN FEATURES BUILT IN FOR TEST.

APPLYING DESIGN FOR LEAK TESTING.

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 4

CARRIAGES THAT FORM THE JET FAST

TRANSFER SYSTEM DIAGNOSTIC.

DESIGN AND MATERIAL FAULTS

ATMOSPHERE SIDE

VACUUM

BUTTON

TRACK WAY THE CARRIAGES RAN IN

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 5

ONE OF THE FOUR IVIS IMAGING UNITS

MOUNTED ABOVE THE TORUS VESSEL.

OVERCOMING THE LACK OF LEAK TESTING FEATURES

IN-VESSEL INSPECTION SYSTEM (IVIS)

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 6

OVERCOMING THE LACK OF LEAK TESTING FEATURES

BELLOWS LINE

HELIUM SPRAY

LINES

PUMPING PORT

ADAPTER

HEATER TAPE

BAKE OUT /

THERMAL CYCLING

LEAK TEST

PREPARATION

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 7

THE WINNING GASKET PROFILE

CUSTOM DESIGNED KNIFE EDGE

TO SUIT ALIGNMENT WITH UNIT

END OF UNIT FORMING SEAL

SURFACE ON GASKET

OVERCOMING THE LACK OF LEAK TESTING FEATURES

TAPER

LOCATION

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny @ btinternet.com – No 8

OVERCOMING THE LACK OF LEAK TESTING FEATURES

SPECIAL COPPER GASKET

SPLIT LOCKING COLLET

BACKING RING

PUMPING PORT ADAPTER

“A”

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 9

TAPER PROFILE COPPER GASKET POST

THERMAL CYCLING AND LEAK TESTING

TAPER PROFILE GASKET WITH

WITNESS MARK FROM IVIS UNIT

REVERSE OF GASKET SHOWING

THE KNIFE EDGE WITNESS MARK

OVERCOMING THE LACK OF LEAK TESTING FEATURES

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 10

OVERCOMING THE LACK OF LEAK TESTING FEATURES

HOW THE SPLIT CLAMP MIGHT LOCATE

ON THE TAPER OF THE IVIS UNIT

TWO HALVES OF SPLIT CLAMP WHICH

BOLTS UP AROUND IVIS UNIT

PUMPING PORT ADAPTER WOULD BE CLAMPED TO THE

FACE OF THE UNIT VIA BOLTING THROUGH THESE HOLES

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 11

DESIGN AHEAD FOR TESTING

INNER LINE

OUTER LINE

WELD / TEST

/ WELD, ETC

APPROACH

OUTER WELDS TESTED IN ONE GO

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DESIGN AHEAD FOR TESTING

COMPLEX MACHINED PUMPING PORT ADAPTER

REQUIRED TO LOCATE ON A TAPER SECTION

SIMPLE PUMPING PORT ADAPTER BASED ON A STANDARD

VACUUM FITTING AND LARGER RUBBER BUNG

INNER LINE

ADAPTER

OUTER LINE ADAPTER

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 13

PRE-POSITIONED CUSTOM KNIFE EDGE

TO ALLOW EASY TESTING OF ITEM

CUSTOM GASKET

DESIGN FEATURES BUILT IN FOR TEST

SPLIT CLAMP

IDEAL FEATURE

TO CLAMP TO

WELDS UNDER TEST

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 14

DESIGN FEATURES BUILT IN FOR TEST

TWO HALVES OF SPLIT CLAMP

FIT AROUND ITEM AND BOLT UP

CLAMP FORMS BOLTING

RING SO ITEM CAN BE

BOLTED DOWN TO SEAL

CUSTOM SIZE

COPPER GASKET

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4K SHIELD

4K ARM ATTACHED VIA

INDIUM SEAL TO 4K SHIELD

77K SHIELD

4K SHIELD PUMPING

PORT ADAPTER

4K SIDE ARM PUMPING

PORT ADAPTER

APPLYING DESIGN FOR LEAK TESTING

4K SHIELD INDIUM SEAL

4K SHIELD INSIDE

77K SHIELD

4K = -269°C

77K = -196°C

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ACKNOWLEDGEMENTS.

University of Leicester (UoL) & UoL Space Research Centre (SRC), Leicester, UK.

Courtesy EFDA JET and Culham Centre for Fusion, Oxfordshire, UK.

Babcock International Group, Whetstone, Leicestershire, UK.

Oxford Instruments plc (O.I.), Nanoscience, Tubney Woods, Oxfordshire, UK.

ConFlat (CF) – registered trademark of Varian Inc.

Edward & Sammy Limpenny, presentation technical support.

Thanks to – SRC / UoL – Terence Ashton, Virgil Taillandier, Dr Gauthier Torricelli,

Dr Jon Lapington, Colin Brooks, Baden Favill, Steve Leach, Kevin Turner, Chris

Bicknell, and Kamlesh Chandarna – JET – Chris Warrick – Babcock – Mick Aylwin

– O.I. – Mike Venman.

4th Vacuum Symposium UK – 16th / 17th October 2013 – Design for Leak Testing – R.J.Limpenny – limpenny@btinternet.com – No 17

THANK YOU FOR YOUR ATTENTION

Robert Limpenny., IEng., MInstNDT.

Email – limpenny@btinternet.com

Tel – 00-44-(0)116-2891123