Gas pipe size

[Phoenix_V]

23 minutes ago, Tony Brooks said:

 

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.

afaik the 15 mm (or any other water pipe is not likely to meet the thickness (of the pipe wall requirements) of the ISO/RCD wheras the imperial sizes (as sold for refrigeration) are available in the required thickness. As far as BSS goes how would they know?

Edited November 21, 2023 by Phoenix_V

[MtB]

18 minutes ago, Phoenix_V said:

As far as BSS goes how would they know?

 

The spec is written on the side of the pipe these days.

 

As the chair polishers dream up ever more 'safety requirements', I can imagine a day arriving where gas pipe without the specification marked on the outside being an automatic fail. 

 

 

[system 4-50]

Bubble testers have a maximum throughput, not that it is relevant in this small load case.  So I had two.  No inspector ever used them, they all connected a manometer instead.  One did eventually show that gunk from the bottles was getting down the lines which was useful.  Bubble testers do introduce extra joints but they live in the relatively safe area near the bottles.  In my next boat, probably on the Astral Plane, I will not bother with installing them.  (One ispector said I should have installed only one bubble tester with a bypass loop and valves.)

[BWM]

I'd start by looking at the size of the fittings on water heater and cooker, this shows their designed input and will save on unnecessary reducing with fittings. Most are 3/8" on standard lpg appliances. 

[TandC]

Slight diversion but connected to the topic - if I were to go into my local council-run (not university etc)  library and enquire as to whether they can provide access to specific ISO standards such as this discussed here, what exactly am I asking for....   Is it just "how can I access ISO Standards please..."

 

Or are these buried in something else?  

 

I've done a quick online search through the library catalogue service for "ISO Standards" - "British Standards Online" etc -but it doesn't return anything so prior to going to talk to someone at the library it'd be good to know what to actually ask for..... 

[MtB]

10 minutes ago, BWM said:

I'd start by looking at the size of the fittings on water heater and cooker, this shows their designed input and will save on unnecessary reducing with fittings. Most are 3/8" on standard lpg appliances. 

 

This is a misunderstanding. 

 

The connection size tells one nothing about the length of pipe supplying the appliance and therefore the pressure loss. The calcs need to be done. 

[Phoenix_V]

51 minutes ago, TandC said:

Slight diversion but connected to the topic - if I were to go into my local council-run (not university etc)  library and enquire as to whether they can provide access to specific ISO standards such as this discussed here, what exactly am I asking for....   Is it just "how can I access ISO Standards please..."

 

Or are these buried in something else?  

 

I've done a quick online search through the library catalogue service for "ISO Standards" - "British Standards Online" etc -but it doesn't return anything so prior to going to talk to someone at the library it'd be good to know what to actually ask for..... 

As you are in Oxford according to your profile https://www.oxfordshire.gov.uk/residents/leisure-and-culture/libraries/reference-online/z-list

[Alan de Enfield]

 

2 hours ago, BEngo said:

"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.

 

 

I think the BSS specification changed when the RCD (ISO specs) changed.

[BWM]

51 minutes ago, MtB said:

 

This is a misunderstanding. 

 

The connection size tells one nothing about the length of pipe supplying the appliance and therefore the pressure loss. The calcs need to be done. 

The OP already stated it is a very short run, so why not use the input size? It would seem pointless to go smaller than the terminal size.

[TandC]

26 minutes ago, Phoenix_V said:

As you are in Oxford according to your profile https://www.oxfordshire.gov.uk/residents/leisure-and-culture/libraries/reference-online/z-list

Thanks - i just found via a slightly different route - but one that probably applies to other areas - the library has a Business and Intellectual Property Centre (BIPC) and one of the services they provide is full access to the Standards. 

 

 

[Slim]

6 hours ago, Tony Brooks said:

 

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.

Tony, point taken. I mentioned 15mm as an indication of size only. Indeed, when I installed my pipework I was advised that household copper pipe was not acceptable.  

[truckcab79]

6 hours ago, BWM said:

I'd start by looking at the size of the fittings on water heater and cooker, this shows their designed input and will save on unnecessary reducing with fittings. Most are 3/8" on standard lpg appliances. 

‘Fraid not.  Not bought the oven yet but the water heater is 3/4”. 

[BWM]

18 minutes ago, truckcab79 said:

‘Fraid not.  Not bought the oven yet but the water heater is 3/4”. 

Crikey, that's massive!

[Tony Brooks]

20 minutes ago, BWM said:

Crikey, that's massive!

 

Could this be the usual BSP size v actual size mistake?

[Tracy D'arth]

1 hour ago, Tony Brooks said:

 

Could this be the usual BSP size v actual size mistake?

Its probably a 1/2" BSP threaded connection which of course measures 20mm, 3/4" OD. Common error for those not used to gas fitting.

It is much easier to use soft copper pipe in imperial sizes as the compression fittings are most commonly imperial and it is easier to work the pipe in a boat. Small appliances on short runs will be 5/16" pipe usually,  3/8" is the next size if the required flow is larger or the run longer.

I would expect the water heater to need 1/2" pipe at least, keep the run short.

Beware of the bubble tester, even 10mm may not be large enough so it is better to use an 8mm one, out of the box, with a bypass valve in 1/2" to achieve sufficient flow for the water heater.

Edited November 21, 2023 by Tracy D'arth

[truckcab79]

1 hour ago, Tony Brooks said:

 

Could this be the usual BSP size v actual size mistake?

Just reading from the manual to be honest. Packed away currently. It’s definitely not 8/10mm. Way bigger. Manual says 1/2” water connections 3/4” gas. 

[magnetman]

12 hours ago, blackrose said:

 

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.

 

 

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

 

 

 

The point is that in general when one buys a boat with a gas system on board it already has a test point somewhere inside the boat. I've had BS inspectors use uscrewed cooker jets for this too but this may be a bit unusual.

 

I know you did your own gas system and of course the OP is intending to do the same so I accept your position as probably better than mine in that scenario. I've never had a new boat or stripped an old and would never choose to do either of these things under any circumstances.

 

So yeah. Bubble tester probably is better in a way as long as it is definitely protected from movement of the gas bottles.

 

12 hours ago, blackrose said:

 

 

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.

There is the test where you turn the gas orf for x amount of time then come back and light the cooker. If it lights and burns for the expected time (you test this with a known sound gas system) then there isn't a leak.

 

 

The regulator pressure is enough to show up leaks. If it wasn't then the cooker would not light after closing the gas for x amount of time but in reality the cooker does light because there is no leak.

 

 

Let's not get into the one about using a match to test for leaks on newly installed joints in gas piping while the bottle is turned orf but the regulator is supplying pressure.

 

That's a terrible idea.

 

 

[wakey_wake]

On 21/11/2023 at 03:21, magnetman said:

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.  [...]

Ah hmm. My ass glocker is way too big to not use the remaining space - it's in the bow under the T-bar.

Currently holding two Calor propane which might be 13kg, chained in. Water hose, 16A cable, car wash brush just in case it's ever Sunday afternoon (!) and couple bags of coal. If I tidied up there would be space for loads of the other junk too.

 

The plumbing is way up under the top aft edge of the locker (annoyingly hard to read markings on the auto-swap valve) and the only way anything is going to fall on it would be getting hung up to 45° in a lock.

 

Should I add some kind of guard for the piping? Partition it? Really waste all that lovely space?

And I do wonder what's underneath, because it has a flat bottom & doesn't go down to the baseplate or show much curvature.

 

My preferred plan is to remove the ghastly. The nice fat inverter arrived today, more LiFePO4 on the way, thanks Black Friday! 🤑

but I hear what y'all are saying about all-electric boats... and gas did make my coffee during the last power cut.

 

Edited November 29, 2023 by wakey_wake
remove double post. bug: submit did not clear the form.

[MtB]

24 minutes ago, wakey_wake said:

And I do wonder what's underneath, because it has a flat bottom & doesn't go down to the baseplate or show much curvature.

 

 

Water tank, often.

 

And... it can't go down to the baseplate or the gas locker drain could not discharge overboard. 

 

 

[magnetman]

Some gas lockers are partly flooded by design and have a slot cut out for the drain. 

 

BS inspection includes checking condition of the base of the locker and also checking the bottles can not move or foul pipework / regulator. 

[Ronaldo47]

My understanding is that the potential problem with using washing-up liquids (such as Fairy) for leak detection,  is that their detergent has had salt added to it to make the solution thicker. A neutral pure soap (Johnsons baby shampoo?) that does not contain salt should be better.  My late father was a pipe fitter at the local gasworks, and always used to use a detergent solution (Daz, Surf, or Omo washing powder, whatever mum had), but that was in the days when iron pipe was universally used. 

 

When washing-up liquids started to be sold (mid- to late- 1950's I think), he did once bring home a gallon tin of concentrated  industrial detergent from work (BP By-Prox I think).  It was as runny as water, which made it difficult not to dispense too much from a refilled Squeezy/ Fairy bottle.   That probably partly accounts for the use of added salt.

Edited November 29, 2023 by Ronaldo47
typos

[wakey_wake]

2 hours ago, wakey_wake said:

And I do wonder what's underneath,

1 hour ago, MtB said:

Water tank, often.

I'll know when I take the lid off that. Job for spring maybe?

Rust from the water tank is what killed the original domestic water pump. I've been putting it off, I'm too tall to go down that 'ole.

However when I look at the (defunct) bow thruster's cofferdam, it looks deep enough to terminate the water tank. And if it doesn't, how will I ever clean the forward part?

Mysteries or messes for another day...

 

 

1 hour ago, magnetman said:

BS inspection includes checking condition of the base of the locker and also checking the bottles can not move or foul pipework / regulator. 

Reading between the lines: junk in the trunk is not advisable, but won't cause BSS failure?

Paint could use a coat, but if it's 30 years old it has done well. Better than the poor old bilge which has a high tide mark.

[truckcab79]

Just dragging  this back up now I’ve got my bubble tester (10mm) in hand.  Need to get some pipe. As far as I can see current BSS regs make no mention at all of wall thickness. Just that it should be seamless.  ISO says 0.8mm up to 12mm. Given that readily available 10mm microbore is 0.7mm generally I see no reason not to use this it as for the sake of 0.1mm it cant fail the BSS anyway. 

 

not missing anything am I?   

Edited December 28, 2023 by truckcab79

[TandC]

46 minutes ago, truckcab79 said:

Just dragging  this back up now I’ve got my bubble tester (10mm) in hand.  Need to get some pipe. As far as I can see current BSS regs make no mention at all of wall thickness. Just that it should be seamless.  ISO says 0.8mm up to 12mm. Given that readily available 10mm microbore is 0.7mm generally I see no reason not to use this it as for the sake of 0.1mm it cant fail the BSS anyway. 

 

not missing anything am I?   

Mine was replaced last year in 10mm / 0.7mm pipe purchased from Screwfix and it passed BSS fine, with a 10mm bubble tester.    

[Alan de Enfield]

54 minutes ago, truckcab79 said:

Just dragging  this back up now I’ve got my bubble tester (10mm) in hand.  Need to get some pipe. As far as I can see current BSS regs make no mention at all of wall thickness. Just that it should be seamless.  ISO says 0.8mm up to 12mm. Given that readily available 10mm microbore is 0.7mm generally I see no reason not to use this it as for the sake of 0.1mm it cant fail the BSS anyway. 

 

not missing anything am I?   

 

Probably not a good idea to advertise the fact as both C&RT and the BSS read the forum.

 

I'd suggest you go and buy the correct stuff and comply with the specification, and then post how happy you are having used the right-piping.