Just had an argument about tightness testing

[kirkgas]

As many will know, its quite possible to have no perceptible drop but still have a smellable leak.

Equally, in the right circ you could have a drop or a rise which isnt attributable to leakage/let by.

where can you have a leak that is large enough to smell but doesnt show as a drop on a u gauge? unless you mean on the upstream side of the ECV

 

[mylesy]

You can have fluctuations with the pipework temperature, but in rare circumstances you could have let by from the ecv and a leak at the same rate, so it shows no drop but there is a leak, in two places. You would be unlucky to get that. But if in doubt, unscrew the governor and spray leak detector into the closed ecv.

 

[radswilldo]

I would say that I have to contact southern gas to either change the ecv(let by) or governor(working pressure let by) on 1 in every 6 safety checks I do. I do not understand chaps that don't do let by/tightness tests when cariing out safety checks/servicing!

 

[billybob150811]

havent read all the post but your bang on in my book ryster i do a let by and tightness before starting work so if there is a problem you let them know before you start dont know if its manditory but i do better safe than sorry

 

[tamz]

Devils Advocate.

Who is to say, after you do your let by test then open and close the valve to increase the pressure for your test, that the valve is still holding 100%?

All that is between you and a leaking ECV is perhaps a bit dried out grease!

 

[kirkgas]

You can have fluctuations with the pipework temperature, but in rare circumstances you could have let by from the ecv and a leak at the same rate, so it shows no drop but there is a leak, in two places. You would be unlucky to get that. But if in doubt, unscrew the governor and spray leak detector into the closed ecv.

if you have a leak rate at the same rate as the ecv lets by this is why you do let by at 10mb and TT at 20mb, so that the leak will show on the TT, as it is being done at a different pressure

 

[mylesy]

Take it you not has it before then, trust me it happens. Found the leak to be on a boiler, isolated it then retested, at 10 mbar at first as you rightly say you should, and I had let by. Which didn't show at first. Had transco fit a new ecv, I fixed the boiler. All good after that. That's why I'm saying it's not always so obvious, even with the guide lines and and so on. You have to be confident and know what your doing.

 

[gazzathebassman]

generally a tightness test is carried out , if it is a new supply,or the supply has been turned off, if you are going to work on the actual installation or add appliances, or the customer suspects a gas leak (smell of gas). You dont have to do a tightness test if you are servicing an appliance ,unless your company wants you to do one, as you can isolate at the isolating valve test disturbed joints with LDF. Contrary to a previous reply, a tightness test includes a let by test for 1 minute at 7-10mb, a temperature stabilisation for 1 minute at 20-21mb, and a tightness for 2 minutes at 20-21mb / this is for a low pressure installation. Its never been acceptable for a stabilisation test to be done with the let by test (thats for bartdude pubmember attention)

 

[Alex Knight]

generally a tightness test is carried out , if it is a new supply,or the supply has been turned off, if you are going to work on the actual installation or add appliances, or the customer suspects a gas leak (smell of gas). You dont have to do a tightness test if you are servicing an appliance ,unless your company wants you to do one, as you can isolate at the isolating valve test disturbed joints with LDF. Contrary to a previous reply, a tightness test includes a let by test for 1 minute at 7-10mb, a temperature stabilisation for 1 minute at 20-21mb, and a tightness for 2 minutes at 20-21mb / this is for a low pressure installation. Its never been acceptable for a stabilisation test to be done with the let by test (thats for bartdude pubmember attention)

Threads 4 years old hope they'd have worked it out by now

 

[Ray Stafford]

Threads 4 years old hope they'd have worked it out by now

Or gone KABOOM!

 

[Dotty]

And as such. Closed.

 

[newcastle phill]

Or is it ?? [emoji12]
Maybe I have been given super mod powers to open threads just by looking at them !!!

 

[firemant]

Well Kirk teaches the rules every day,so now I guess he's on a busmans holiday

Kirk is spot on, as always.
But teaching every day is no guarantee of accuracy.
I was in a training centre recently, and the trainer absolutely insisted there should be no flexible connection on a suspended heater.

 

[newcastle phill]

Familiarity breeds contempt so it goes lol .....