Safety Valve -inspection failure

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Safety Valve -inspection failure

Post  MrStationHouse on Sat 09 May 2015, 11:52 am

I am at the NTET training weekend this weekend and someone had brought a 6" Burrell. He was told by the site safety officer that his safety valve was unsafe and won't pass a boiler test. The reason being that if the spring failed the lever is not secured and would fly off.

His would be boiler inspector was also there and said that before he could get a test cert he would need to have a strap to secure it.

Has any one had any similar problems?

Simon

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Re: Safety Valve -inspection failure

Post  LiveSteam on Sat 09 May 2015, 12:14 pm

Interesting, I'd think 99% of our type of engines i.e minitures, would fail that one Neutral

TBH I'm not sure it would actually go far if the spring did fail ? would depend which end the spring broke I suspect.

Flicking through NTET's own inspection regime on their website I can see no mention of such a strap ?

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Re: Safety Valve -inspection failure

Post  LiveSteam on Sat 09 May 2015, 12:27 pm

Scrap that thought Embarassed

They are or appear to be bolted to the front safety valve, well mine is on the Burrell, so I dont think it can ping off.


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Re: Safety Valve -inspection failure

Post  MrStationHouse on Sat 09 May 2015, 1:18 pm

My safety valve is only held down by the spring.

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Re: Safety Valve -inspection failure

Post  LiveSteam on Sat 09 May 2015, 1:31 pm

Mine seems to be like this



And I am assuming the front of the lever is secured to the front valve ?

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Re: Safety Valve -inspection failure

Post  Kiwiconnection on Sat 09 May 2015, 2:23 pm

OMG it looks as though NTET have a jobsworth member who knows absolutely nothing about steam engines and engineering at all. Shocked

Virtually every traction engine, full size and miniature, use that stile of safety valve and have done for over 100 years. So what’s so bloody special about this particular valve? I assume that he will be sending everyone at the meeting home with their tails between their legs as most of the engines at the meet will probably have the same type of valve. Sad Sad

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Re: Safety Valve -inspection failure

Post  lynnr on Sat 09 May 2015, 3:12 pm

The lever is free floating on both valve heads. The pivot point is used to even out any miss alignment of the two barrels. My commercial inspector and father (ex commercial inspector) have no problem with the design of the safety's. The inspector has even had the safety valves off to see how they were constructed and to make sure clear and free.

The showman loco does not have a problem anyway as th extension pipes fully arrest the lever by virtue of their construction.

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Re: Safety Valve -inspection failure

Post  Capricorn1 on Sun 10 May 2015, 1:34 am

The photo posted by Livesteam shows a set of valves that does not have the retaining link to prevent the valves and lever being blown skywards should the spring fail - this I believe is the point the inspector was making.

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Re: Safety Valve -inspection failure

Post  Capricorn1 on Sun 10 May 2015, 3:12 am

If you look at most photo's / drawings of Ramsbottom Safety Valves you will see the lever has a slot below the spring anchor hole connected to a retaining link.
It's probably been left off for ease of manufacture but it is a safety device so could prove to be a can of worms, don't go slagging a boiler inspector off from the side lines - just remember it's his signature that states your boiler / engine is safe to operate.
As I'm only half way through my build I don't know the detailed construction of the valves on our RL's.

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Re: Safety Valve -inspection failure

Post  MrStationHouse on Sun 10 May 2015, 5:35 am

I have managed to clarify the details and apparently because the 6" has a certain water capacity it has to have the strap. Our 4" is below this so it ok. That said it is a good point especially as becaus the engine is small it is possible if it broke someone could be looking over it so I may try and engineer a solution at some point.

Best wishes
Simon

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Re: Safety Valve -inspection failure

Post  LiveSteam on Sun 10 May 2015, 12:47 pm

lynnr wrote:The lever is free floating on both valve heads. The pivot point is used to even out any miss alignment of the two barrels.

Thanks Lyn, I am still an early learner at these things have have yet/need to pull my safeties apart.



MrStationHouse wrote:I have managed to clarify the details and apparently because the 6" has a certain water capacity it has to have the strap. Our 4" is below this so it ok. That said it is a good point especially as becaus the engine is small it is possible if it broke someone could be looking over it so I may try and engineer a solution at some point.

Best wishes
Simon

Ah now that makes sense, did some more looking and the full size stuff does appear to have a holding strap up the centre of the spring from what I could see on photos ? although if we start going down the route of " someone could be looking over it" then we best not ever light a fire in them in the first place Rolling Eyes

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