Gallery, Projects and General > How do I??
threading
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John Rudd:
 :mmr:
--- Quote from: RobWilson on April 15, 2015, 12:59:43 PM ---Hi Lads

I think Polecats air receiver will be fine its made for the job , BUT an ill fitting threaded plug is another thing all together with roughly ,1400Lb (+/- a little bit )  of force  behind it     :med:


Rob

--- End quote ---

So in order to prove the integrity of his newly made plug, he ought to pressure test the receiver with water before filling with any compressed gas.....?
RobWilson:
Hi John

Aye a hydraulic test to twice working pressure of the  vessel  would be the safe way to test the integrity of the plug .  :thumbup:


Rob 
Jonny:
Wise words Rob, although max operating pressure is 2700psi it should withstand min 4050psi. Theres no laws governed like scuba its not a removable cylinder. I know, don't ask same results remember that Ginb 'tatting' about with a titanium cylinder that went up serves him right, had it been ok then it could have happened to the new owner or anyone else in the vacinity.

Titans later Falcons with metric threads were never tested, just the prototype.
Steel end plug decent fit I wouldn't doubt it would take 8000psi.
The weakest link is irrelevant of any reg Peter its the end plugs and or the tube. Certain English and Korean made wouldn't get through a test centres door seen rooks blow from 235bar recommended pressure 200bar then they started fitting burst discs to mask the incompetence.

Original end plugs are brass for the Titan/Falcon, 20yrs passed and fairly sure its M22X1.25 with o ring at back of thread so exposed.

Closer could test to 10000psi hydraulically no one in right mind would pump a gas in to test, fill with water and pump oil in. My worry on this replacement end plug one was the naff brass HW100 fill probe seen at 300bar registered on hydraulic unit.

Always pays to max out available thread with a better tolerance fit. Tip aluminium keep oiled or it will pick up and lock up solid, more you rotate the more it locks up. M30X0.75 top original rated at 200bar, factory initial prototype test 300bar German rated, below exceeds that.


polecat:
thank you everybody i will proceed carefully
polecat
David Jupp:
Unlikely to be an issue on something of such modest diameter, but be aware that lots of pressure equipment is never tested to as high as 2xMWP these days - it all depends on the standards applied.

If not intended to be used at elevated temperature, original pressure test might be as low as 1.43 x MWP, or it may never have been pressure tested at all.

Always arrange any pressure test based on the assumption that failure may occur.
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