Gas pipe size

[truckcab79]

An oft asked question that seems to get people in a spin so I’ll add to it and ask again about gas pipe sizes. At this stage I’m only really interested for the purposes of buying bubble tester, bulkhead fittings, and thinking about where it will run. Keeping access to fittings for BSS etc.

 

So…. What size copper pipe. 8mm or 10mm? 
 

Only gas appliances will be a Cointra / Pegaso / Ferolli Eco 6 water heater and a small

oven and hob. Probably something like the Thetford Triplex. 
 

From reading it seems that it used to be the case that you couldn’t go too large, and then someone started panicking about the amount of gas potentially sat in the pipes so current thinking seems to be that you should go ‘large enough’. 
 

And is it the case that ALL joints should be compression.  No soldered fittings at all?  
 

 

 

[Slim]

12 minutes ago, truckcab79 said:

An oft asked question that seems to get people in a spin so I’ll add to it and ask again about gas pipe sizes. At this stage I’m only really interested for the purposes of buying bubble tester, bulkhead fittings, and thinking about where it will run. Keeping access to fittings for BSS etc.

 

So…. What size copper pipe. 8mm or 10mm? 
 

Only gas appliances will be a Cointra / Pegaso / Ferolli Eco 6 water heater and a small

oven and hob. Probably something like the Thetford Triplex. 
 

From reading it seems that it used to be the case that you couldn’t go too large, and then someone started panicking about the amount of gas potentially sat in the pipes so current thinking seems to be that you should go ‘large enough’. 
 

And is it the case that ALL joints should be compression.  No soldered fittings at all?  
 

 

 

Sometimes one can over research an issue. Given that the greatest risk from gas piping would be from a leak. I fail to see how the volume of gas within a given length of pipe is of any significance. Far more important is how gas might escape into the cabin of a boat. The greatest weakness is obviously at joints. Soldered joints are a no, no. Think of the reasoning behind the ban. Solder melts at a fairly low temperature . A soldered joint could fail in the event of a non gas related fire thereby turning the fire into a gas related fire of greater intensity. Easy when you think of it. As I understand it brazed or silver soldered joints are acceptable both of which require a much higher temperature to fail ie melt.   

[truckcab79]

Cheers. I was pretty certain from the BSS criteria that that was the case. I’m more used to residential where in the main soldering is considered far superior. Odd that it’s never seen as an issue in homes. I understood the perceived risk was more to do with fatigued joints due to vibration rather than heating temp though. If the fire is hot enough to melt your soldered joints you need to have been out the way long before  that. 
 

Any idea on the 8/10 question?  

[Alan de Enfield]

5 minutes ago, truckcab79 said:

Any idea on the 8/10 question?  

 

 

Why not just follow the ISO specification for gas installation in 'small Craft' (there is a later issue of this spec)

 

Note : "Small Craft" is defined as up to 24 metres length

 

 

 

Edited November 20, 2023 by Alan de Enfield

[truckcab79]

Cheers for that. Not seen that before. Was working from BSS. 

[Alan de Enfield]

Just now, truckcab79 said:

Cheers for that. Not seen that before. Was working from BSS. 

 

The BSS is basically a watered down version of the ISO

[truckcab79]

Which is probably all I need for one pipe feeding two appliances a few feet away but cheers for the extra info. 

[Slim]

14 minutes ago, truckcab79 said:

Any idea on the 8/10 question?

I just used 1/2" (aka 15mm). It was malleable and ran from the cockpit isolation valve (as required at the time) to the appliances without joints.. Getting it through the forward bulkhead and fashioning a suitable grommet was 'interesting'.   

[Alan de Enfield]

14 minutes ago, truckcab79 said:

Which is probably all I need for one pipe feeding two appliances a few feet away but cheers for the extra info. 

 

There is a table in the spec that will show you exactly the size of pipe you need for YOUR appliance gas usage. It also takes into account the length of run and has a multiplication factor for each bend and joint (they all effectively add 'length' due to flow restrictions)

 

eg : A 'T' or 'elbow' adds 0.6 metres equivalence.

 

If you install to the spec then it will meet the BSS.

 

Check the latest version of the spec to ensure there have been no changes.

Edited November 20, 2023 by Alan de Enfield

[truckcab79]

Just now, Alan de Enfield said:

 

There is a table in the spec that will show you exactly the size of pipe you need for YOUR appliance gas usage. It also takes into account the length of run and has a multiplication factor for each bend and joint (they all effectively add 'length' due to flow restrictions)

 

If you install to the spec then it will meet the BSS.

 

 

Cheers. Annex A you mean?  Yes. Already had a copy of that as it happens. 
 

None of which really answers the original question especially as Slim has run his in 15mm and almost all of the bubble testers are  8mm or 10mm so it seems.  
 

According to the table 8mm for mine is fine but really I wanted to know I suppose if 10mm was going to cause an issue in case I decided to upgrade to larger units later.  

[MtB]

22 minutes ago, Alan de Enfield said:

 

 

Why not just follow the ISO specification for gas installation in 'small Craft' (there is a later issue of this spec)

 

Note : "Small Craft" is defined as up to 24 metres length

 

 

 

 

Point of Order....

 

Thats well out of date. The current edition according to my notes is 2017, not 2008. 

 

There might even be a later version! 

[Alan de Enfield]

Just now, MtB said:

 

Point of Order....

 

Thats well out of date. The current edition according to my notes is 2017, not 2008. 

 

There might even be a later version! 

 

 

I KNOW - and as I mentioned in each post that this is an older version and :

 

7 minutes ago, Alan de Enfield said:

Check the latest version of the spec to ensure there have been no changes.

 

 

[truckcab79]

2020 is current according to what I found.  

[Alan de Enfield]

5 minutes ago, truckcab79 said:

None of which really answers the original question especially as Slim has run his in 15mm and almost all of the bubble testers are  8mm or 10mm so it seems.

 

 

You do realise that Bubble Testers are not mandatory don't you ?

[truckcab79]

4 minutes ago, Alan de Enfield said:

 

 

You do realise that Bubble Testers are not mandatory don't you ?

I didn’t, but it states:

 

24. All LPG systems must have a suitable means to test that the system is gas-tight.

 

And bubble testers are the only type I’ve read about to date.  What others would you suggest?   

[blackrose]

8 minutes ago, truckcab79 said:

I didn’t, but it states:

 

24. All LPG systems must have a suitable means to test that the system is gas-tight.

 

And bubble testers are the only type I’ve read about to date.  What others would you suggest?   

 

Other suitable means to test gas tightness include a bleed nipple in the system for someone with a drop tester such as an inspector to use. But if you have a functioning bubble tester in the gas locker you don't need a bleed nipple.

Edited November 21, 2023 by blackrose

[truckcab79]

I’ll just get a bubble tester.  Seems sensible to  have something I can easily use to test the system myself if I choose to.  

[blackrose]

5 minutes ago, truckcab79 said:

I’ll just get a bubble tester.  Seems sensible to  have something I can easily use to test the system myself if I choose to.  

 

That was my thinking when I installed my gas system, it's a very easy way to test the system. Other forum members constantly deride bubble testers, usually without explaining exactly why they don't like them.

 

By the way, when I test my system which I do at least every time I change a gas bottle, I press the button for a full minute. I've got one of those cheap magnetic LED lights attached to the bottle to make sure there's enough light shining though the sight glass of the bubble tester.

 

 

The bubble tester only tests the low pressure side of the system after the regulator, so after I change a bottle I also spray a bit of leak detector spray (Screwfix) onto the brass pigtail fitting which goes into the gas bottle to make sure the high pressure side isn't leaking. As it's in the gas locker it's not such a safety issue but I once lost a full bottle overboard in about 2 weeks and they usually last me 6 months, so a small leak there can get quite expensive. You can also use a washing up liquid solution, but don't use it on other joints as it's corrosive. People say they wash it off afterwards but if a washing up liquid solution is drawn into a joint by capillary action, how would one know if it's been rinsed off properly inside, or if it's still sitting there attacking the olive? I'd rather spend a fiver on a can of non-corrosive leak detector spray.

[truckcab79]

Many thanks. 
 

Every gas guy I know just uses soapy water. Mind you I normally find pro gas / plumbers / sparkys are the worlds worst for what I would consider best practice or just tidy work.  You should see the condensate pipe I found when refitting a shower today.  Kinked and shoved into a hole drilled into the soil pipe with a load of silicone smothered over it. Oh and running uphill just for good measure.  🙄

 

I’ll fit the bubble tester.  I like the idea of them and to be honest half of this forum seems to deride pretty much everything anyone else does so it doesn’t surprise me that some don’t like them. 😂

[blackrose]

1 hour ago, truckcab79 said:

Every gas guy I know just uses soapy water. Mind you I normally find pro gas / plumbers / sparkys are the worlds worst for what I would consider best practice or just tidy work.  You should see the condensate pipe I found when refitting a shower today.  Kinked and shoved into a hole drilled into the soil pipe with a load of silicone smothered over it. Oh and running uphill just for good measure.  

 

. 😂

 

That's the trouble with most tradespeople - they just don't care. They're on the clock so they're rushing which is understandable, but so many do half arsed jobs. Nobody loves your boat like you which is why I always try to do everything myself. I just do plenty of research, take my time and the result is generally better than I'd get even if it was possible to find someone to come to the boat. 

 

I've got no trade skills, but I fitted my entire gas system myself and it's been passed and even praised by 4 different BSS inspectors. Let's face it, when you speak to some of these tradespeople they're not the brightest individuals. So my approach has always been, if that guy can do it then I'm sure I can do it myself. 

2 hours ago, truckcab79 said:

None of which really answers the original question especially as Slim has run his in 15mm and almost all of the bubble testers are  8mm or 10mm so it seems.  

 

According to the table 8mm for mine is fine but really I wanted to know I suppose if 10mm was going to cause an issue in case I decided to upgrade to larger units later.  

 

You'll most likely be using Imperial size soft copper pipe. So if you're using the 8mm bubble tester I think that's equivalent to 5/16" imperial (others can correct me if that's wrong). If you're using larger pipe what you can do is either use additional fittings to reduce and expand to get your pipe though the 8mm bubble tester. I don't think additional joints inside the gas locker are viewed as "unnecessary" under BSS rules. However, it's not an elegant solution and you may run out of space with all those joints. So a better plan is to do what I did and simplify things by using a 10mm bubble tester. Put the bubble tester in a vice and crack off the fittings and then you can replace the olives and compression nuts with the correct imperial sizes for your pipe. 

[magnetman]

I was told by BS inspectors that you need a bubble tester if the boat is a 'primary residence' but not if it isn't. 

 

I don't like bubble testers on principle as it seems to me that adding more connections into a system where you definitely don't want any leaks is a bad move. 

 

Also it it was in the gas locker you have to be certain the bottles can't move and accidentally impact it and that nothing else is kept in the locker. 

 

Good test for leaks is turn bottle orf leave overnight then light the cooker in the morning. The gas retained in the pipework with regulator pressure means in a sound system the gas will light for a short time then go out. 

 

This should also work over longer time periods. 

 

 

 

[blackrose]

3 hours ago, magnetman said:

I don't like bubble testers on principle as it seems to me that adding more connections into a system where you definitely don't want any leaks is a bad move. 

 

That principle seems based on flawed thinking to me. If you have extra connections for a bubble tester within a gas locker that doesn't represent any safety issues because a leak within the locker will drain overboard. However if you don't have a bubble tester you must have a test nipple on the low pressure side of the system in the cabin. That test nipple will have its own connections and so ironically results in more connections overall on the side of the system where any leak won't drain overboard.

 

I'm not saying one is better than the other. I'm just saying your principle doesn't make sense. If you're concern is about losing gas overboard though a bad high pressure connection you'd simply use some leak detector spray on the bubble tester connections, as you would for any other connection on that side of the system if your gas bottle seemed to run out too quickly.

 

3 hours ago, magnetman said:

I was told by BS inspectors that you need a bubble tester if the boat is a 'primary residence' but not if it isn't. 

 

That's a new one on me. I don't think it's true.

3 hours ago, magnetman said:

Good test for leaks is turn bottle orf leave overnight then light the cooker in the morning. The gas retained in the pipework with regulator pressure means in a sound system the gas will light for a short time then go out. 

 

I don't think that's a good test. I think it's a very crude test. The only acceptable tests I know of for soundness/integrity of a gas system are either a drop test or a bubble test, but there may be other tests I don't know about.

Edited November 21, 2023 by blackrose

[Jen-in-Wellies]

59 minutes ago, blackrose said:

 

3 hours ago, magnetman said:

I was told by BS inspectors that you need a bubble tester if the boat is a 'primary residence' but not if it isn't. 

 

That's a new one on me. I don't think it's true.

Sort of true in practice, but a little more complicated. If the boat is used as a primary residence, then the BSS inspector needs to be Gas Safe registered before they can do any work on a gas system. Connecting a manometer to the test point counts as work, so they can't do it if not registered, with the additional LPG and boat qualifications on their card. So you could have a live aboard boat with no bubble tester, but you would either have to get a rare BSS inspector with Gas Safe registration, or get and pay for both a BSS inspector and an almost as rare boat qualified Gas Safe fitter in at the same time to carry out this check.

In practice, it is a lot easier to get a bubble tester fitted, as pressing the button on top counts as not working on the system and any BSS inspector can do it to check that the system is leak free.

See this from the BSS web site:

Quote

The BSS Examiner may ask you about your boat's use:

The examiners who are not on the Gas Safe register are advised as part of their initial dealings with owners to ask in advance of turning up at the mooring, about the status of the craft.

To avoid falling foul of UK law and avoiding criminal prosecution they need to find out whether the boat's use will mean they should not carry out a tightness-test using a manometer.  They may ask the following questions, just for their own personal record:

• Is the boat hired out in the course of a business?
• Is the boat used primarily by anyone for domestic or residential purposes (In this matter, it makes no difference to if the boat is owner-occupied or rented-out)?
• Are people invited on board the boat in the course of a business, e.g. is it a café or shop?

Even if the answer to all the questions above is 'no', the examiner is advised to make a brief record that he or she has asked the questions and received the negative answers. This information will not be shared with BSS Office or other parties unless there is an investigation linked to gas testing by the examiner.

 

[Tony Brooks]

8 hours ago, Slim said:

I just used 1/2" (aka 15mm). It was malleable and ran from the cockpit isolation valve (as required at the time) to the appliances without joints.. Getting it through the forward bulkhead and fashioning a suitable grommet was 'interesting'.   

 

I think this is misleading. 1/2" gas tube has a thicker wall than 15mm household copper pipe. I am not sure if ordinary 15mm copper meets the ISO or BSS, I have an idea that at one time it did not.

[BEngo]

"Ordinary" 15 mm copper pipe used for gas did not initially meet the BSS requirements.  Then someone (possibly Roger Lorenz)  did some hoop stress calculations and showed that 15 mm copper was perfectly strong enough and would withstand bottle pressure in the event of a regulator failure.  BSS then agreed to accept it.

 

"Proper" half hard gas pipe does have a greater wall thickness.  This makes it easier to get a good, non-wrinkled or linked bend, so possibly cutting down on the number of fittings needed.

 

I have not looked at the ISO recently, so I am not sure what it now specifies.

 

N