Rank: Forum user 
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We have a routine maintenance process (every 3 months) where our mechanics have to remove “bullet like” items from a pressurised brake wheel in an engine room. According to the mechanics the pressure behind each of these “bullets” is around 17,000Psi.
The problem:-
The mechanics must remove the safety enclosure – awkward process which can’t be re-designed due to space restraint. Also, whilst removing there is an increased chance of knocking/catching a “bullet” and possibly having it released within the area.
So far our only last defence for protection is wearing PPE and ensuring EVERY member of staff is fully aware and trained to work with the system.
They wear a full face mask – EN 166:2001 (Imported from America). Does anybody know the standards for PPE whilst working with pressurised systems of this nature?
The mechanics have requested bullet proof vests for the process…..reasonable idea?
Any thoughts on this would be a great help…..
Thanks very much.
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Rank: Forum user 
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It must be pressurised for a purpose. But removal of these things, even inadvertently, releases the pressure (ie, the come out under great force, that is the risk)
If pressure is lost presumably the brake wheel is presumably not effective and the engine #should# be non-operational.
So why not stop the engine and release the pressure, under control, before other work commences?
There may not be a pressure release valve, but if you can create the pressure can reverse that mechanisms to release it?
I actually had a gun pointed at me a few weeks ago. But the though of an engineer wanting a bullet-proof vest is astonishing. I'd be looking for a different job!
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Rank: Super forum user 
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Well this one is certainly different? As standard, PPE should be last resort but if you do go down that road you will have to speak to the manufacturers to establish whether they have a product that will protect against your 'bullet like' objects. I'm assuming your 'bullet like objects' are something other than copper jacketed lead, aerodynmically efficient projectiles?
You will also need to establish the blunt trauma effect of the projectile stiking the body even if it is stopped by the armour.
My gut instinct is that body armour would not be considered suitable or sufficient given the nature of the risk you have described (for a start it will only cover the vital organs, from a millitary perspective that works because it is likely to be the centre mass that is targeted, a failing machine won't be so deliberate)
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Rank: Super forum user 
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I have worked with presure systems for a good part of my life but 17000 psi is higher than I have worked with. The golden rule is normally that the pressure is released before commencing work on the system. If that is possible then I suggest you look towards doing that.
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Rank: Forum user
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Thanks for the response guys.
When I first saw this process I immediately asked if the system could have the pressure released remotely/safe distance etc before commencing work. There are pressure release valves on the wheel but valves are in close proximity to the “bullets” ......tricky whilst using tools to loosen valve.
It is a delicate operation to even remove the safety guard, one knock of a “bullet” may dislodge it, and this then automatically releases the remaining 4/5 around the wheel.
As far as accidents / near misses go – thankfully nobody has been hurt in this process, but there was a near miss (before my time) where one became dislodged, shot upwards cutting a clean through a lump of plastic. The projectile was never found….
Any more adive would be welcomed.....?
Thank you all once again.
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Rank: Super forum user
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Replace the manually operated valve with a solenoid operated valve? The operating controls could then even be put in a different room.
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Rank: Forum user
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I suppose I should ask, does it have to be like that and if so what idiot designed such a dangerous piece of equipment?
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Rank: Super forum user 
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If I were your maintenance guys I too would be nervous of these pressures. Highest I ever worked with was 4500 psi.
You seem to describe one common circuit having a retained static pressure across all of these bullets, as opposed to one with a pump sustained pressure?
Is there perhaps a gas accumulator in the circuit (quite common in high pressure dynamic applications), which could be bled on the gas-side to bring the hydraulic pressure down to a much safer level in the first instance?
The system must surely have a facility somewhere/somehow to allow it to be safely de-energised as already discussed?
Anyway, when your chaps have replaced these "bullets" they will have to re-pressurise the system. How do they do that? Perhaps we can consider that process in reverse, maybe using the bleed valve on a hydraulic hand-pump. Presumably the connection valve is accessible without disturbing the safety enclosure.
Key phrase there I think: "safety enclosure". No way should that be tampered with until the system is de-energised.
Dare I ask -what happened to the manual and log book, and is the manufacturer not still around to answer these questions?
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