Gas leak

[GUMPY]

Seems like it's a regular occurrence?

 

 

Edited April 9, 2021 by Loddon

[blackrose]

24 minutes ago, Loddon said:

Seems like it's a regular occurrence?

 

 

 

If by regular you mean once every 11 years then you may have a point. Without reading the whole thread, from memory the only other gas leak I've had was from the back of my gas water heater and that wasn't one of my joints, it was the heater manufacturer's.

[Alan de Enfield]

 

All this talk of bubble testers is quite interesting when the RCD (Recreational Craft Directive) actually requires a pressue gauge to be incorporated so you can watch for leaks, (but I have yet to see one installed).

 

 

RCD Requirement under : ISO 10239 "Small craft -- Liquefied petroleum gas (LPG) systems"

 

 

4 General provisions

 

4.1 An LPG system and all its components shall be capable of withstanding storage at −30 °C to +60 °C.

 

4.2 LPG systems shall be of the vapour withdrawal type, i.e. fuel released only under gas phase conditions.

 

4.3 All LPG appliances installed on the craft shall be designed for use at the same working pressure.

 

4.4 Each system shall be fitted with a pressure gauge. The gauge shall read the cylinder pressure side of the pressure regulator. The gauge scale shall have a pressure range from 0 kPa to a minimum of 1 200 kPa and a maximum of 1 400 kPa.

NOTE The purpose of the gauge is to provide a convenient, simple means to test the system for leakage before each use of the appliances. The gauge does not provide an indication of liquid LPG remaining in the cylinder, only its vapour pressure, which is a constant at any given temperature.

 

 

10 LPG installation system tests

 

10.1 Before putting the LPG system into operation, verify, from the connection at the pressure regulator to the closed burner valves at the appliances, that the system has been correctly installed; prior to charging the system with LPG, submit it, with shut-off valves open, to an air pressure test at three times the nominal pressure but not more than 0,015 MPa. The system shall be deemed sound if, after a period of 5 min (to allow for pressure equilibrium), the pressure remains constant at ± 0,000 5 MPa for the following 5 min. An appropriate leak detection fluid may be used on connections to locate sources of leakage. NOTE Foam producing solutions for leak detection on gas installations in accordance with EN 14291 meet these requirements.

 

CAUTION — Ammonia, which is present in some soaps and detergents, attacks brass fittings. Although damage is undetectable at first, brass fittings may crack and leak within a matter of months after contact with ammonia.

 

10.2 All connected appliances, including the function of the flame supervision devices at the burners and pilot lights, shall be subjected to a burner function test following the system pressure test. A visual check for flame lift off due to excessive pressure at individual burners shall be made; a visual check for adequate flame height shall also be made with all appliance burners in the system operating (this ensures adequate, not excessive, working pressure at each appliance).

 

10.3 Where a bubble leak detector is permanently fitted in the system, it shall be securely mounted in the low pressure side of the system and in the cylinder housing or cylinder locker. A pressure gauge shall be installed in the high pressure side of the system. See 4.4.

[blackrose]

2 minutes ago, Alan de Enfield said:

 

All this talk of bubble testers is quite interesting when the RCD (Recreational Craft Directive) actually requires a pressue gauge to be incorporated so you can watch for leaks, (but I have yet to see one installed).

 

 

Thank goodness very few of us bother with the recreational craft directive on this forum.

[Tonka]

Sorry to say but I would not let a "gas safe engineer" work on my boat. Having had a "corgi " engineer work on a house I owned once and then left me with a leak because of a dry joint in a soldered union. 

[ditchcrawler]

14 minutes ago, Alan de Enfield said:

 

 

CAUTION — Ammonia, which is present in some soaps and detergents, attacks brass fittings. Although damage is undetectable at first, brass fittings may crack and leak within a matter of months after contact with ammonia.

 

You would think all the taps and plumbing fitting around the sink would fall to pieces, The ones on my boat have been contaminated with washing up liquid for almost 20 years and over 35 in the house, but non have cracked or fallen to pieces yet.

[Ex Brummie]

https://www.ebay.co.uk/itm/UK-Combustible-Gas-Leak-Detector-Methane-natural-Gas-Tester-Sound-Alarm-Sensor/223988711771?hash=item3426c4815b:g:6boAAOSwNHZeo~9h

 

I find one of these invaluable for finding small leaks. For last BSS, after lay up last year, when testing before BSS, every hob tap was leaking ,I removed the gas rail and greased the taps but all to no avail, so new cooker time.

It is possible the isolators are leaking around the spindle. You may need to remove the operating handle to see with leak detector.

[blackrose]

1 minute ago, Ex Brummie said:

https://www.ebay.co.uk/itm/UK-Combustible-Gas-Leak-Detector-Methane-natural-Gas-Tester-Sound-Alarm-Sensor/223988711771?hash=item3426c4815b:g:6boAAOSwNHZeo~9h

 

I find one of these invaluable for finding small leaks. For last BSS, after lay up last year, when testing before BSS, every hob tap was leaking ,I removed the gas rail and greased the taps but all to no avail, so new cooker time.

It is possible the isolators are leaking around the spindle. You may need to remove the operating handle to see with leak detector.

 

Thanks I might buy one of those.

 

I think I can remove the handle from one of my isolators but not the other. I'm going to do that overnight test than Nicknorman recommended. Close both isolators overnight and purge any gas in the lines to the oven and hob. See if there's any gas in the lines in the morning by trying to light the hob.

[Ex Brummie]

Just be sure to remove the batteries after use. It is easy to leave them for a long time and they corrode. It is also wise to test after switching on before you start to look for leaks. A disposable gas lighter, or similar is good for this.

[bizzard]

If any of the isolator taps are the old tapered plug cock type these can be restored if leaking by removing the nut and spring washer on the back, withdraw the tapered plug and handle and lap it in to the female taper with a spot of rubbing compound T-Cut, dilute with a drop of water for final lap,  twisting back and forth similar to lapping in engine valves to their seats.

[blackrose]

8 minutes ago, Ex Brummie said:

Just be sure to remove the batteries after use. It is easy to leave them for a long time and they corrode. It is also wise to test after switching on before you start to look for leaks. A disposable gas lighter, or similar is good for this.

 

Thanks, I've ordered one from Amazon for the same price. The benefit of Amazon is that returns are easier and less hassle than ebay if you do need to send something back.

 

I'll test it with a lighter before starting. 

 

Would you take a 9v battery out of a multimeter for the same reason? I've got a few bits of kit with batteries inside that lay around for years. Maybe I should check them all.

[blackrose]

I don't think it's going to be very easy to take the handle off the bigger isolator unless I take the whole isolator off, in which case I'd probably just replace it. 

 

Sorry I meant a gas safe engineer will just replace it...?

 

In case you were wondering, the pipe in the picture below is the branch to the oven. The yellow handled isolator is on the main pipe behind it.

 

 

Edited April 9, 2021 by blackrose

[bizzard]

3 minutes ago, blackrose said:

I don't think it's going to be very easy to take the handles off the island isolators unless I take the isolators off, in which case I'd probably just replace them. 

 

Sorry I meant a gas safe engineer will just replace them...?

 

In case you were wondering, the pipe in the picture below is the branch to the oven. The yellow handled isolator is on the main pipe behind it.

 

 

I don't think those taps are the tapered plug cock type but ball valve type.

I always understood that it's ok to carry out gas work on ones own boat but not to perform gas work on other peoples.

[blackrose]

6 minutes ago, bizzard said:

 

I always understood that it's ok to carry out gas work on ones own boat but not to perform gas work on other peoples.

 

I thought the distinction was that competent people can carry out work on any gas system on anyone's boat, but if that boat is used as liveaboard accommodation then only a gas safe engineer should work on it - and that rule includes one's own boat.

Edited April 9, 2021 by blackrose

[bizzard]

4 minutes ago, blackrose said:

 

I thought the distinction was that competent people can carry out work on any gas system on anyone's boat, but if that boat is used as liveaboard accommodation then only a gas safe engineer should work on it - and that rule includes one's own boat.

Ok, Apart from brand new already fitted out boats I doubt if very many other boats, sailaways for example had their gas systems installed by a qualified boat gas safe bod.

[nicknorman]

39 minutes ago, blackrose said:

 

I thought the distinction was that competent people can carry out work on any gas system on anyone's boat, but if that boat is used as liveaboard accommodation then only a gas safe engineer should work on it - and that rule includes one's own boat.

That is often said by people in the trade because they want a closed shop (and your money), however if you actually read the GSIUR it just says that anyone working on gas must be competent, it then goes on, at great length, to talk about working on gas as employment (getting paid for it) and that requires gas safe registration.

 

So as far as I can tell, to work on your own gas the law only requires you to be competent. Of course, if anything goes badly wrong, clearly you weren’t competent and you might be successfully prosecuted.

[blackrose]

1 hour ago, bizzard said:

Ok, Apart from brand new already fitted out boats I doubt if very many other boats, sailaways for example had their gas systems installed by a qualified boat gas safe bod.

 

I think you're probably right.

[blackrose]

1 hour ago, nicknorman said:

 

So as far as I can tell, to work on your own gas the law only requires you to be competent. Of course, if anything goes badly wrong, clearly you weren’t competent and you might be successfully prosecuted.

 

Either that or you'll be brown bread so they can't prosecute you.

[plumbob]

I am a Gas Safe Registered engineer

I would suggest you be very clinical and careful if you are doing this yourself as you know LPG is heavier than air and is a much more fickle gas to deal with than Natural Gas. See Link

https://www.installeronline.co.uk/wp-content/uploads/2014/07/Testing-procedure.pdf

 

The grease required for sealing dried out gas taps is Molycote grease available from BES

 

If you really want to test your self i usually use the half way system, remove and cap the nearest joint on the cooker end of the system to the pipe coming from the gas cylinder and test at the bubble tester for 2 mins. No bubbles you can rule out the pipe and anything up to the bubble tester, bubbles showing, then you will have to locate and check every joint also spray bubble test fluid around the bubble tester button shaft. If the main pipe is sound then you can reconnect the pipe and work your way along towards cooker. 

Any smell of gas in the gas locker is RED FLAG leak detection fluid on all joints even the pipe up to and including the bottle connection and the shaft seal on the bottle tap (had those leak on my own boat). One issue with LDF is that a large leak creates a bubble and bursts it quickly so not always easy to find.

The electronic leak detector is a good thing have one myself, however do not use it after spraying with any fluid all joints should be dry as the detector will misinterpret the vapour coming from the fluid as gas as they react to many chemicals other than gas and don't try to use it for prolonged periods in the same location as it can acclimatise itself to the environment. Take it outside and reset every five to ten mins.

Also don't assume that the shut off valve near the cooker is shutting off, again can be tested by disconnecting down  stream and a little LDF on the outlet with the vale turned off.

My experience is that the cooker is the most likely source of the leak loads of valves and joints.

Having done this sort of thing for years on natural gas it can be time consuming and tedious.

 

One last thing before pursuing the leak turn of all electrical systems on the boat for obvious reasons, gas + spark = at best explaining to wife how you blew up the boat or worse ..........

Hope this helps

[Ex Brummie]

3 hours ago, bizzard said:

I don't think those taps are the tapered plug cock type but ball valve type.

I always understood that it's ok to carry out gas work on ones own boat but not to perform gas work on other peoples.

they are both ball valve types, and the seals on the ball will be nitrile or EPDM. both of which can degrade over time.

[blackrose]

44 minutes ago, plumbob said:

I am a Gas Safe Registered engineer

I would suggest you be very clinical and careful if you are doing this yourself as you know LPG is heavier than air and is a much more fickle gas to deal with than Natural Gas. See Link

https://www.installeronline.co.uk/wp-content/uploads/2014/07/Testing-procedure.pdf

 

The grease required for sealing dried out gas taps is Molycote grease available from BES

 

If you really want to test your self i usually use the half way system, remove and cap the nearest joint on the cooker end of the system to the pipe coming from the gas cylinder and test at the bubble tester for 2 mins. No bubbles you can rule out the pipe and anything up to the bubble tester, bubbles showing, then you will have to locate and check every joint also spray bubble test fluid around the bubble tester button shaft. If the main pipe is sound then you can reconnect the pipe and work your way along towards cooker. 

Any smell of gas in the gas locker is RED FLAG leak detection fluid on all joints even the pipe up to and including the bottle connection and the shaft seal on the bottle tap (had those leak on my own boat). One issue with LDF is that a large leak creates a bubble and bursts it quickly so not always easy to find.

The electronic leak detector is a good thing have one myself, however do not use it after spraying with any fluid all joints should be dry as the detector will misinterpret the vapour coming from the fluid as gas as they react to many chemicals other than gas and don't try to use it for prolonged periods in the same location as it can acclimatise itself to the environment. Take it outside and reset every five to ten mins.

Also don't assume that the shut off valve near the cooker is shutting off, again can be tested by disconnecting down  stream and a little LDF on the outlet with the vale turned off.

My experience is that the cooker is the most likely source of the leak loads of valves and joints.

Having done this sort of thing for years on natural gas it can be time consuming and tedious.

 

One last thing before pursuing the leak turn of all electrical systems on the boat for obvious reasons, gas + spark = at best explaining to wife how you blew up the boat or worse ..........

Hope this helps

 

Thanks for this. What is LDF?

 

I installed the system and it's passed 4 BSS inspections so far so I think I'm adequately competent and I do understand the hazards of LPG on boats.

 

I would have guessed it was the hob or oven too but assuming the isolators are working then the leak seems to be upstream of the isolators. I'm away for about a week for work but I'll hunt down the leak when I get back with detector spray and electronic detector and let everyone know what I find.

21 minutes ago, Ex Brummie said:

they are both ball valve types, and the seals on the ball will be nitrile or EPDM. both of which can degrade over time.

 

Maybe it is the hob or oven then.

[David Mack]

1 minute ago, blackrose said:

What is LDF?

Leak detecting fluid?

[blackrose]

17 minutes ago, David Mack said:

Leak detecting fluid?

 

Ah ok thanks

[Iain_S]

11 hours ago, Alan de Enfield said:

 

All this talk of bubble testers is quite interesting when the RCD (Recreational Craft Directive) actually requires a pressue gauge to be incorporated so you can watch for leaks, (but I have yet to see one installed).

 

 

RCD Requirement under : ISO 10239 "Small craft -- Liquefied petroleum gas (LPG) systems"

 

 

4 General provisions

 

4.1 An LPG system and all its components shall be capable of withstanding storage at −30 °C to +60 °C.

 

4.2 LPG systems shall be of the vapour withdrawal type, i.e. fuel released only under gas phase conditions.

 

4.3 All LPG appliances installed on the craft shall be designed for use at the same working pressure.

 

4.4 Each system shall be fitted with a pressure gauge. The gauge shall read the cylinder pressure side of the pressure regulator. The gauge scale shall have a pressure range from 0 kPa to a minimum of 1 200 kPa and a maximum of 1 400 kPa.

NOTE The purpose of the gauge is to provide a convenient, simple means to test the system for leakage before each use of the appliances. The gauge does not provide an indication of liquid LPG remaining in the cylinder, only its vapour pressure, which is a constant at any given temperature.

 

 

(snip)

I don't see how a pressure gauge on the high pressure side can give any indication of leakage, unless it's a major leak which would be obvious without it. A leak on the low pressure side will release a relatively small quantity of gas in a short space of time and any pressure drop will be concealed by LPG in the cylinder going from a liquid to a gaseous state. Conversely, if there is a high gas demand, the temperature of the cylinder will drop, leading to a drop in pressure. 

[ditchcrawler]

8 hours ago, Iain_S said:

I don't see how a pressure gauge on the high pressure side can give any indication of leakage, unless it's a major leak which would be obvious without it. A leak on the low pressure side will release a relatively small quantity of gas in a short space of time and any pressure drop will be concealed by LPG in the cylinder going from a liquid to a gaseous state. Conversely, if there is a high gas demand, the temperature of the cylinder will drop, leading to a drop in pressure. 

If you close off the cylinder the pressure should remain static, if you have a leak in the high or low pressure side it will leak away. A bubble tester will only detect leaks down stream of the bubble tester.  We use to leak test using helium gas mixed with nitrogen as if will pass through smaller holes.