Gas Pipe - Size?

[Talulah]

I've removed the galley worktops and it's an ideal opportunity to run a new length of copper gas pipe.
Can anyone tell me what size I should run (metric or imperial)? Length of run about 8m.
Many thanks.

 

[Cloven]

If it was me, I would replace with whatever was there before as this means you will be able to use your previous end fittings - you'll just need new olives.

Also, assuming you have a gimballed cooker, its an ideal opportunity to replace the flexible braided coupling between the copper piping and the cooker which has a limited life span anyway (10 years I think?)

There is problem about still getting imperial fittings etc.

 

[npf1]

I've previously been advised:

3/8 copper for 3 burner cooker plus oven.
1/4 copper for 3 burner cooker plus oven.

 

[NormanS]

Split the difference, and go for 5/16 or 8mm (to all intents the same bore), but be careful to get the correct thread sizes to suit the various valves and appliances.

 

[VicS]

There is no problem as far as I am aware in obtaining and using imperial sized pipe and fittings. You will probably be best advised to stick with what ever is used at present, likewise for the actual size of pipe to use. The inlet fitting on the cooker may well be the size to adopt.

Some links that may be useful

http://www.calormarineshop.co.uk/ for useful advice and a source of pipe and fittings.

http://www.bes.co.uk/ for what may well be more competitive prices than from Calor.

http://www.boatsafetyscheme.com/downloads/BSS_Guide_chap7.pdf The part of the "Boat Safety Scheme" for privately owned boats that deals with LPG installations.

When done you will want to test the installation. even if you opt for a test by a Corgi registered installer (Still Corgi at present I think although that is changing)
Details of the tests can be found HERE

 

[timtap]

I used to sheath the copper pipe inside flexible water pipe to give the pipe added protection from the possibility of chafing.

 

[VicS]

[ QUOTE ]
I used to sheath the copper pipe inside flexible water pipe

[/ QUOTE ] Properly clipped up at the intervals specified for the BSS should prevent chafing. Metal bulkhead are the main concern perhaps but you dont get many of them in an AWB.

I wonder if the need for the pipe to be visible can be rationalised with sheathing it in water pipe.

A good tip where it is necessary to maintain integrity of a bulkhead or the gas and air tight exit from the gas locker is to use a bulkhead fitting that has been bored through to remove the land in the centre so that it can be slipped onto the pipe without the latter being cut. That eliminates two possible leakage points. If space is tight one half of the fitting can even be cut off.

 

[Heigaro]

[ QUOTE ]
I've previously been advised:
3/8 copper for 3 burner cooker plus oven.
1/4 copper for 3 burner cooker plus oven.

[/ QUOTE ]

Hmmm... but what if you have a 3 burner cooker plus oven?? /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

 

[vyv_cox]

My old Plastimo Atlantic, 20+ years, was fitted with a 1/4 inch (6 mm) gas pigtail. Its replacement has an 8 mm pigtail. They are both two burners plus grill plus oven. The new one is currently running well on the old 6 mm pipe, pending time to upgrade right through to 8 mm. So I guess the answer is to replace with the best fit for the stove but going up a size if there is any doubt. One additional point is that 6 mm pipe and fittings are quite difficult to obtain in Europe at DIY and chandlery outlets, whereas 8 mm is available almost everywhere. This applies particularly to the armoured hose with a copper pigtail at each end, which I have never found abroad in 6 mm.

 

[NormanS]

I was reqired to run my new 5/16 copper gas pipe within a plastic pipe by The Boat Safety Scheme, as enforced by British Waterways, on boats coming under their jurisdiction. That was a few years ago now, and they may have changed the rules since then. Practically it was quite difficult to do. I guessed at the total length required - quite long, straightened out the required length, and then threaded it into clear braided plastic hose. You are then faced with threading this size through all the twists and turns on the boat. I sealed the inboard end with silicon, and left the outside end open, so that in the highly unlikely event of the copper pipe springing a leak, the gas would flow along the plastic tube to outside. It all seemed a bit of overkill to me.

 

[nimbusgb]

I needed to replace my 6mm run of about 8m since the 6mm simply would not allow enough butane through when it was warm and the cooker wouldn't even light if the temp was in the single digits. The pressure from a butane regulator is 28mb ( does anyone do and ADJUSTABLE butane regulator? ) , next to bu**er all, the loss in 8m of tubing was just too much and the cooker ran one ring with a sooty flame. the really crazy thing is that the 6mm was OEM equipment and the boat is 24 years old!

Changed the whole run to 10mm now I can run 3 rings and the oven. 10mm fittings are a little harder to find in this country but easier on the continent.

 

[VicS]

[ QUOTE ]
I was reqired to run my new 5/16 copper gas pipe within a plastic pipe by The Boat Safety Scheme

[/ QUOTE ] I see no such requirement in the current, Aug 2005, edition of the scheme.

 

[pennycar9]

I was so fed up with low gas flames and long cooking times that I ripped all our gas pipe out and relpaced it with 10mm soft copper. the original was 1/4" running 4 burner hob and oven,water heater and part time fridge,(gas when we were at sea)We now have no problems and you can get 10mm soft copper and all the fittings you need from good plumbers merchants the likes of Plumb Center or PTS. While you're there get a tin of Gas Tight paste and you will have no problems.
As said before, as long as the new pipe is adequetly and firmly fixed by properly fitting clips, you will not have the problem of chafing. On completion of the new installation I would get a tin of gasleaking testing arosol spay, or use a mixture of warm water and Fairy liquid brushed onto the joints,(with the gas turned on of course) to test for leaks. Bubbles from a joint indicates the joint is unsound.

It is well worth upsizing your gas pipe as it makes the kettle boil quicker!!!!!!!!!!

 

[VicS]

I have just spotted that Talulah is a boat used commercially as a sailing school boat.

A different version of the Boat safety scheme will I think apply. the one for Hire vessels etc: (In as much that any version of the BSS will apply)

http://www.boatsafetyscheme.com/downloads/Part%207.pdf

I have not read it so I dont know what differences there are.

re the suggestion to get stuff from Plumb Center .... I think they have gone out of business (Good riddance if they are all like the one I went to)

Re the suggestion to buy some Gastite paste. Please note that no jointing compound should be used on compression fittings. It should only be used on tapered thread joints. Tape can also be used on those but it is a special tape, not the same as used for water.

BTW copper olives , not brass, are recommended for gas installations

We are advised not to use washing up liquid for detecting leaks. it is said to be corrosive!

For a boat that is to be used commercially a full test by a Corgi Installer is vital, maybe mandatory

 

[pennycar9]

With all due respect, from a gas fitter to a chemist, where is it written that you must not use Gastite on Gas joints? I use it more or less daily on various applications and unless the information I have from Corgi is wrong, then there is no problem.
Yes Fairy liguid is mildly corrosive but is still the best indication of a leak.Better than the arosol cans that costs a fortune. Why not wash down the tested area with clean cold water on completion of testing.

The Plumb Centers, although not my favorite institution, have not gone belly up, or at least they werent this afternoon when I went to the Gt Yarmouth branch for some gas fittings.

 

[Malcb]

As an ex-gas man, I concur /forums/images/graemlins/grin.gif

 

[VicS]

[ QUOTE ]
where is it written that you must not use Gastite on Gas joints

[/ QUOTE ] Not on compression fittings. Please read what I actually wrote.

See HERE

The correct grade of tape or jointing compound are fine, necessary even, for tapered thread joints. Calor sell Rocol Gasseal.

A little confused by the fact that "Gas-Tite" is sold for lpg but that Boss "Gastite" is only suitable, according to Boss, for natural gas and town gas.

I did not actually say I believed there was a major problem with washing up liquid. merely repeated the advice normally trotted out. Anyway the installation should be pressure tested (two tests I believe in the Corgi book) and the spray, or wup liquid, used to locate any leaks if indicated by the pressure test.

Will the change from Corgi to Capita's "Gas Safe Register" in April have any implications for anyone?

 

[vyv_cox]

<<< I did not actually say I believed there was a major problem with washing up liquid. merely repeated the advice normally trotted out. >>

I too have read this on several occasions. I believe that washing up detergent is thickened by the addition of salt, sodium chloride, which of course is in plentiful supply around most boats, so I have always ignored this advice and used it to test for leaks.

The only rider I would add is that the viscosity and surface tension of soapy water is incredibly low, so it is sometimes difficult to ensure that the top part of a fitting is actually covered with the solution. The commercial leak detectors are thickened and stick quite well, but as said are very expensive for a one-off use.

 

[VicS]

[ QUOTE ]
I believe that washing up detergent is thickened by the addition of salt, sodium chloride

[/ QUOTE ] I've read that too but have vague recollections of checking some in the lab and finding it wasn't. I should have tested a variety of brands I suppose.

 

[DJE]

There is a pipe sizing table on the Calor Marine Site here. First you need to know the total power of all the burners in your cooker. Assuming four burners at 1.5kW the total will be 6.0kW. As I read the table (and the units are a bit confusing) a 30 foot run of 5/16" pipe will give your 4.41kW from butane and a 30 foot run of 3/8" will give you 10.79kW from butane. So you will need the 3/8" pipe if you want to get 6kW.
We replaced our cooker a couple of years ago and increased the pipe size from 1/4" to 5/16" for a pipe length of about 15 feet. With the old cooker and the smaller pipe there wasn't enough gas to run all the burners at full power. I would always err towards the larger pipe (especially with a long pipe run) and use reducers at the end as necessary. I'm not a gas expert just an engineer with a rudimentary knowledge of fluid mechanics. I had a CORGI man do the installation on my boat.