0.5mb drop on tightness test - Should I be worried?

[EastMidsTiler]

Hi everyone,

Just looking for some advice/reassurance. My boiler had its second annual service today and the (gas safe) engineer recorded a 0.5mb drop on the tightness test. He assured my partner that this was nothing to worry about but as I wasn't home at the time I just wanted reassurance that this is okay? British Gas did the first service and it was nowhere near as comprehensive as carried out today. I suspect this result would have appeared first time around but either the test wasn't carried out or it wasn't recoreded.

As we only have the boiler and hob running on gas is there anyway this "leak" can be located? Isolate the applicances indivually? Sniffer test? Or is this harder to find than a needle in a haystack?

And lastly, is this likely to be increasing our gas bill?

I should say the engineer was in no way worried and has signed off job sheet as safe so I'm probably worrying about nothing.

Thanks,

 

[fixitflav]

they would say its within safe limits why did you go looking for the leak when you didnt need too

Agreed, there almost certainly isn't a leak, and none within the meaning of the regs. No system would be totally leak free - if you left it for a year the pressure would fall. As others have said, change of temperature could easily cause that sort of pressure change. A fall of about 0.15°C is all it needs for the pressure to fall by 0.5mb.

 

[Old Account]

So your going to test a gas pipe with water

You are funny as usual... how about air or N nitrogenium!?!?!

 

[Old Account]

we don’t use steel for gas pipes in domestic properties. The permissible drop is to cater for old gas valves on appliances, pipework only has to be totally tight.

How come, I come across quite often steel gas pipes which are either under the floor connected to copper or bedded in concrete? However, the point I made is to check for weaknesses and cracks which could be hidden due to slag or other debris.

 

[Sharp Point]

They use to use steel many moons ago and with threaded fittings. I guess with you mentioning slag, that the joints are welded over there?

 

[ShaunCorbs]

You are funny as usual... how about air or N nitrogenium!?!?!

not funny cant air test past 0.5 bar

 

[ShaunCorbs]

How come, I come across quite often steel gas pipes which are either under the floor connected to copper or bedded in concrete? However, the point I made is to check for weaknesses and cracks which could be hidden due to slag or other debris.

you test at op and thats it

 

[Old Account]

A domestic gas installation should be tested at 1 bar for 30 mins ?
Standing pressure is usually well below 30mbar and working pressure 21 +\-2 so probably a bit overkill.
I do agree with zero tolerance though, that’s alway what I aim for anyway even if it’s within permissible drop.

Overkill ? Sorry mate but I disagree with that term. A gas pipe should be tested with a lot higher pressure than just 30mbar. You have to check the pipe under a load test which means with higher pressure than the one you will have when the pipe is in use. You will test the material and joints for weaknesses , hairline cracks or pinholes which are covered by slag. Due to the higher pressure you make sure to find those weaknesses or cracks which you won’t find by mbar.

 

[Old Account]

not funny cant air test past 0.5 bar

Lol and then complaining when properties blow up what a rule.

 

[ShaunCorbs]

Overkill ? Sorry mate but I disagree with that term. A gas pipe should be tested with a lot higher pressure than just 30mbar. You have to check the pipe under a load test which means with higher pressure than the one you will have when the pipe is in use. You will test the material and joints for weaknesses , hairline cracks or pinholes which are covered by slag. Due to the higher pressure you make sure to find those weaknesses or cracks which you won’t find by mbar.

so do you remove the boiler cooker and fires to do the test as these can only take 20 mbar

 

[Old Account]

you test at op and thats it

I know that but we having a discussing about what is right and what is wrong. I personally have a different approach to checking and testing gaspipes.

 

[JTplumbingservices]

You dont need to do a TT on a service

Unless you

Overkill ? Sorry mate but I disagree with that term. A gas pipe should be tested with a lot higher pressure than just 30mbar. You have to check the pipe under a load test which means with higher pressure than the one you will have when the pipe is in use. You will test the material and joints for weaknesses , hairline cracks or pinholes which are covered by slag. Due to the higher pressure you make sure to find those weaknesses or cracks which you won’t find by mbar.

But the pressure in the pipe is in mbar, we’re only talking about domestic installation pipework with a working pressure of 19-23 mbar and standing pressure usually a few mbar higher than that so why the need to test to 1 bar?

 

[Sharp Point]

I know that but we having a discussing about what is right and what is wrong. I personally have a different approach to checking and testing gaspipes.

Do you live in the U.K.?

 

[Old Account]

so do you remove the boiler cooker and fires to do the test as these can only take 20 mbar

Yes, you would need to otherwise you will ruin the appliances. You can only test them via there operating pressure as you know. But when it comes to testing the pipework throughout the property when installed new then you will need to use the appropriate fittings to cap them off and test them with higher pressure ( but that’s the way we do it in Germany ). We do 2 test before bedding pipes into the concrete, load testing ( 1bar with air or N ) for 30min -1hour and then a 15 min test leak test.

Sorry but it is difficult to explain german terms in English. I think you can’t be careful enough when it comes to gas. I know it’s done differently here and I do whatever is required but I would wish few things would be different.

 

[Sharp Point]

Unless you

But the pressure in the pipe is in mbar, we’re only talking about domestic installation pipework with a working pressure of 19-23 mbar and standing pressure usually a few mbar higher than that so why the need to test to 1 bar?

If I can decipher his posts, I think the gas pipework in his home country is welded and welded joints can be terrible, so it makes sense to test at much higher pressure

 

[Old Account]

Unless you

But the pressure in the pipe is in mbar, we’re only talking about domestic installation pipework with a working pressure of 19-23 mbar and standing pressure usually a few mbar higher than that so why the need to test to 1 bar?

We have also 18-25mbar but when it comes to test pipework we have to undertake those tests and get that printed off with a special machine.

 

[Old Account]

Do you live in the U.K.?

Yes

 

[ShaunCorbs]

Yes, you would need to otherwise you will ruin the appliances. You can only test them via there operating pressure as you know. But when it comes to testing the pipework throughout the property when installed new then you will need to use the appropriate fittings to cap them off and test them with higher pressure ( but that’s the way we do it in Germany ). We do 2 test before bedding pipes into the concrete, load testing ( 1bar with air or N ) for 30min -1hour and then a 15 min test leak test.

Sorry but it is difficult to explain german terms in English. I think you can’t be careful enough when it comes to gas. I know it’s done differently here and I do whatever is required but I would wish few things would be different.

dont want to be rude but your / were not in germany doesnt matter what the german standards are there not ours

 

[JTplumbingservices]

We have also 18-25mbar but when it comes to test pipework we have to undertake those tests and get that printed off with a special machine.

So how would you carry out a tightness test in a domestic property after making an alteration to the installation pioework ?

 

[Old Account]

If I can decipher his posts, I think the gas pipework in his home country is welded and welded joints can be terrible, so it makes sense to test at much higher pressure

Yes back in Germany we have steel pipe, malleable pipes, copper pipes which could be welded, screwed or crimped. So I am just trying to say that it would be good if we had 0 tolerances as well as checking pipes slightly different. But as we know it is different in each country. I think you would find much more leaks when pipes are tested with higher pressure and it would just help to rectify the leaks before something horrible happens.

 

[Old Account]

dont want to be rude but your / were not in germany doesnt matter what the german standards are there not ours

You aren’t rude. You are quite right and I agree with that. I was just mentioning my own opinion as we had a discussed about zero tolerances. I just tried to explain few more things in depth. But if you understand my point of view I think you would agree with me that I am not so wrong.

 

[Sharp Point]

I’d like to see the statistics between Germany and the U.K. on gas explosions from leaks, that’ll be interesting

 

[Scott_D]

If I can decipher his posts, I think the gas pipework in his home country is welded and welded joints can be terrible, so it makes sense to test at much higher pressure

welded should be better than any soldered joint!

We should test at 20mb to avoid regulator lockout and not testing pioework the other side of it

 

[Old Account]

So how would you carry out a tightness test in a domestic property after making an alteration to the installation pioework ?

As normal checking ecv Letby 10mbar and after that tightness test of 20mbar

 

[JTplumbingservices]

As normal checking ecv Letby 10mbar and after that tightness test of 20mbar

So you’d be happy with it holding at 20mbar for 3 mins ?

 

[Old Account]

I’d like to see the statistics between Germany and the U.K. on gas explosions from leaks, that’ll be interesting

That would be interesting to me too.

 

[Old Account]

welded should be better than any soldered joint!

We should test at 20mb to avoid regulator lockout and not testing pioework the other side of it

You are right scott. I know that and that’s you would not be able to test the pipework with higher pressures. You would need to test them without having anything connected. We also check only the downstream side of it

 

[Sharp Point]

welded should be better than any soldered joint!

We should test at 20mb to avoid regulator lockout and not testing pioework the other side of it

Not everyone can weld, lots of people can solder. Soldering is easy... you can pretty heat the front of the fitting and add solder... job done( usually)
Try welding a small pipe with tig/ stick / mig

Different story..

So no, welded joints could potentially leak

 

[Old Account]

So you’d be happy with it holding at 20mbar for 3 mins ?

Of course. According to what I learned here I am happy with 3min holding the pressure at 20mbar. If I can’t smell gas

 

[Old Account]

Not everyone can weld, lots of people can solder. Soldering is easy... you can pretty heat the front of the fitting and add solder... job done( usually)
Try welding a small pipe with tig/ stick / mig

Different story..

So no, welded joints could potentially leak

Agree with you. Welding is practing it comes with time. You will need to do it very regularly to have a good decent weld done which doesn’t leak. Do you actually learn welding in apprenticeships? I remember we had to bend steel pipe with sand, welding joints, soldering copper, brazing, ... using basically all kind of materials and fittings.

 

[Sharp Point]

No, steel welding isn’t part of plumbing qualifications, lead welding is though.