UK Knowledge of Pipe Bending and Pressure Testing 31-5-12 Martin Gibson (RAL) Pipe bending by Ian Mercer @ Lancaster University Connector welding by Richard French @ Sheffield University Testing by Martin Gibson at RAL

Pipe Bending All the ATLAS UK pipe bending is performed by Ian Mercer at Lancaster University Simple but carefully manufactured tooling optimised for each pipe diameter and each bend radius. Manual bending with a profiled solid follower Bobbins with deep cut-out to suit pipe diameter

Pipe Bending Metrology Tool Laser micrometer. (Micro-epsilon 2500) Samples a 300 micron ‘slice’ 1 micron resolution, 3 micron reproducibility (better than a blade micrometer as it does not damage the pipe and the user needs no special skills)

Pipe Bending Results Pipe is constrained out of the bend plane by the bending technology

Typical Pipe Bending Summary Max deformation= original tube diameter – minimum in plane diameter

Pipe and Connector Testing Philosophy Need an Experiment Risk Document covers catastrophic failure, environmental considerations, cost, safety. maximum acceptable leak rate (For CO2)

Typical Technology Ranges for Finding Leaks Max (mbar.l.sec-1) [~cc .sec -1] Min Technology 103 (atmospheric) 10-2 Pressure drop 10-7 Helium sniffer 10-1 10-10 Helium leak (sample evacuation) Typical He background.... 4.6. 10-6

Helium Testing What Does it All Mean? Simple test with sample in bag filled with helium and evacuate sample using helium leak detector typically....10-10 limit, BUT sample only has -1 bar pressure differential. Can do at room temp and say -80C

Complicated test with sample pressured using helium (up to say 150 bar), sample in bag and accumulate leak for a fixed period of time ( depends upon the sample volume) and then sample the bag with the sniffer. Calculation gives the real leak rate. (easy by- product is that you know if it blows up!) Can do at room temp and say -80C

Hydraulic Testing Hydraulic testing.. Dangerous if you can’t guarantee all gas in the system is removed. Hydraulic systems always claim a few poor souls every year as the liquids pierce the skin and enter the blood stream. Even with all gas removed if one has a mechanical pump ( as opposed to a man with a manual pump)one still has the above problem. [You have all seen the children toy rockets that use water and air at a few bar, wouldn’t want a silicon module to go the same way!] After the test you do not know for certain that all liquids were removed . However.. it works easily for small samples with simple pipe layout (eg a stave pipe or a connector) but what liquid to use if you want to test at -80C?

Simple hydraulic test system at RAL reservoir Liquid = distilled water Manual pump Can reach 600 bar Multi turn wheel to increase pressure Interlocked test box

Typical Hydraulic Test Data Non linear rise indicates a change in volume ( a rupture!) Various pressure runs allowing pipe diameter to be measured as the test proceeds rupture

UK Current Testing Regime For all stave and stavelet pipes that go into planks for possible fitting with modules we.... A) hydraulically test individual items such (pipes, welds, connectors ) to qualify techniques and materials. We do not hydraulically test stave or stavelet pipe assemblies. B) We Helium vacuum test at room temperature and -80c. ( usually we reach 10-10 , we reject any that fail, only one so far.) C) We pressure test at room temperature and -80C. (not blown one up yet) D) We Helium pressure test at room and -80C (the one that failed the vac test failed this test too)

What might we do in production? No matter what, you need to perform a pressure test to ensure that there will not be a catastrophic failure in each item that will subsequently be used in a situation that may cause stressing of the pipe as far as reasonably practicable. (you can’t for example test items without connectors). Need to certify that the leak rate is commensurate with the requirement from the risk document. Need to ensure that the interior of the pipe is clean from surface contaminants ( this one gets for free from the vac test) Must keep documentation up to date and be able to identify all tested piece parts uniquely