Ye olde gas compression joint thread

[MagicalArmchair]

I have never completed a gas compression fitting in my life - however, this being PBO, I do want to do it myself so if anything fails at sea, I will have the knowledge to put it right (not to mention having the satisfaction of doing it myself).

• I am using 8mm copper pipe, and the fittings are 5/16s - the total difference being 0.06mm between the two and I figure the tolerances of the pipe are such that that won't matter a bosuns parrot.
• I am going to use gas PTFE tape on the (copper) olive, as a secondary seal, and I am going to hand tighten plus half a turn. (I will do some 'test' joints in my garage, take them apart, and make sure the olive doesn't move to ensure they are tight.).

I am getting a bubble tester to go next to the gas locker (alas, no space in it), to test for leaks. I have a gas testing wand arriving too just in case I need to track down any leaks. Additionally I will use some deionised water and shampoo on each joint to test to see whether they leak. Each separate copper run will have a stop cock to isolate it (a kind skipper on here suggested that).

Questions:

• Hand tight plus half a turn of 5/16ths the right amount?
• Now I know I don't strictly need the PTFE on the olive - however, it won't adversely affect the joint will it?
• Seems likes lots of threads everywhere with this sort of install - I'm concerned they might vibrate apart - I note everywhere I have read they say do not put anything on the threads of the compression joints - fair?
• I am using a standard camping gaz regulator to two appliances - cooker and heater - is that okay? (a bit like this one: http://www.gooutdoors.co.uk/camping...ghiSl32RqNKn_tTzCKdn0aAqRO8P8HAQ&gclsrc=aw.ds)
• Can anyone suggest a good video/web guide/blog/book on the subject?

 

[oldbilbo]

Something tells me there will be a skilled and experienced expert along soon to tell you the error of your ways.....'specially the idea of PTFE tape on a copper olive.

You have run this planned DIY work past your insurer, haven't you....?

 

[vyv_cox]

Some people advocate PTFE tape on the olives of plumbing fittings, others consider it to be unnecessary if the job is done properly. Nobody AFAIK advocates it on gas fittings, mainly because the small fibres that will inevitably break off are likely to penetrate the small orifices of jets and control taps. It used to be standard practice to use a liquid sealant, in fact I still have some labelled 'Calortite' but best practice now is to use nothing. Annealed copper olives are very ductile and will make a perfect seal if not over-compressed. Good 'how-to' link http://www.thomson-caravans.co.uk/advice/diyprojects/gascompressionfitting.htm

No necessity at all to use it on the threads of compression fittings, which do not see any gas.

 

[pampas]

Do not use PTFE tape, and the olive need to be deformed and I expect the no of turns will not give you the right deformation. I understand the latest sealing method is to use a Special Poly something sealant squeezed into the union after the olive. personally I used ordinary tap water and fairy liquid or you can get spray fluid made for the job.
I have never come across a nut that's worked loose in a gas system but Murfies law says the it probably is true.

 

[MagicalArmchair]

Ah, thanks chaps, I'll ditch the idea of PTFE then (one less thing to buy too...) - Interesting vyv_cox, that guide recommends one and a half turns, which backs up what you are saying pampas.

And oldbilbo, nope, I havent, my last affair was DIY too - just plain ol' rubber pipe all the way to the cooker so it'll be an improvement on that at least. They will say get another bleeding survey no doubt...

 

[VicS]

Tape or jointing compound should not be used. The fittings are designed to make gas tight metal on metal joints. Tapes and compounds can mask the fact fact that a joint is not correctly tightened.

Advice at http://www.thomson-caravans.co.uk/advice/diyprojects/gascompressionfitting.htm

Copper olives are recommended rather than brass.

If you have more than one appliance each should have a local shut off valve

Use Chapter 7 of the Boat Safety Scheme Essential Guide as your guide but take note of any changes described in the 2013 revised checking procedures


http://www.boatsafetyscheme.org/media/180428/bss guide 2005 complete web.pdf

http://www.boatsafetyscheme.org/media/195630/summary of key ecp changes jan 2013 final 1.0.pdf


This suggested layout from an old PBO may be useful

This is what can happen if leaking gas ignites

The Skipper was seriously injured

 

[michael_w]

Get 8mm fittings from BES. Rather than bodge with 5/16", the sizes are purely nominal.

 

[old_salt]

There is a gas PTFE it's on a yellow spool it's thicker than the standard PTFE.
Have a look at the following there is a ton of help just Google calor gas.
There is an LPG joint compound and a small amount wiped round the pipe and threads the can help the threaded fittings make up without binding up.

:-http://www.boatsafetyscheme.org/media/164540/bss%20guide%20chap7.pdf

http://www.walshsurveyor.com/yachts/articles/gas/index.htm

http://www.ybw.com/forums/showthread.php?175970-Gas-pipe-Jointing-compound-Tape

http://www.calor.co.uk/media/wysiwyg/PDF/using-hoses-and-tubing-250913.pdf

 

[prv]

There is a gas PTFE it's on a yellow spool it's thicker than the standard PTFE.

Yes, and it's meant for threaded joints, not bodging into compression fittings.

Pete

 

[old_salt]

Yes, and it's meant for threaded joints, not bodging into compression fittings.

Pete

I don't think anywhere in my post I recommended it for compression fittings.

 

[vyv_cox]

Have a look at the following there is a ton of help just Google calor gas.

As far as I can see none of those, except possibly the ybw.com link, even mentions sealants and some not even compression fittings.

 

[old_salt]

As far as I can see none of those, except possibly the ybw.com link, even mentions sealants and some not even compression fittings.

True they where put there as general installation help.
I have looked for the Calor Gas installation site but it seems to escape me at the moment.
This one is more about Bulk storage instalations.
:-http://www.calorgas.ie/wp-content/uploads/2013/02/Calor-Installation-Manual-FINAL.pdf

 

[neilf39]

I have done several compression fittings and never used PTFE tape. Only of threaded fittings where it seals on the thread, eg BPS Female with BPST Male.
The olive will deform/compress and make a perfect seal when tightened up on its own.

 

[MagicalArmchair]

Get 8mm fittings from BES. Rather than bodge with 5/16", the sizes are purely nominal.

Thanks Michael, any other views around this? A lot of places (including the guys at Propex) use 8mm and 5/16" interchangeably - in fact fittings are supplied stating they are actually BOTH -http://www.jacksonsleisure.com/caravan-and-camping/gas-fittings/gas-connector-8mm-5-16-compression-nozzle/

Is there really that much of a difference that I should ditch the new pipe I have and buy more pipe?

 

[vyv_cox]

True they where put there as general installation help.
I have looked for the Calor Gas installation site but it seems to escape me at the moment.
This one is more about Bulk storage instalations.
:-http://www.calorgas.ie/wp-content/uploads/2013/02/Calor-Installation-Manual-FINAL.pdf

Yes, gas plumbing is now such a dangerous occupation (!) that most of the useful information that used to be available has been withdrawn. Socal had good info, as you say Calorgas did, and several others. The caravan link I posted earlier is an exception because the 'rules' don't apply to them.

 

[prv]

I don't think anywhere in my post I recommended it for compression fittings.

I suppose not, but it's not an unreasonable conclusion for the reader to have drawn in a thread which is wholly about compression fittings.

Pete

 

[emandvee44]

Gas compression Fittings

I am about to do similar work. I found several videos on utube.
Here is one:-

https://www.youtube.com/watch?v=6YqgAAMy5fk


M.

 

[BERT T]

I normally use Rocol Gaseal on all joints in a low pressure gas line; https://www.rocol.com/products/non-setting-pipe-sealant On compression joints I normally form the joint first then dismantle again and smear Gaseal around the olive before re-assembling. Always fit a bubble leak detector as close to the regulator as possible

 

[MagicalArmchair]

Thanks for reposting that pbo item vics, interesting that the stop cocks are put close to the utilities, not close to the gas... Seems odd doing it that way as if there is a fault in the gas pipe run there is no way to isolate the run and keep the other appliance running?

Any other thoughts on my 8mm pipe vs the 5 16ths fittings?

 

[nigelmercier]

With acknowledgement to similar answers above...

Don't use PTFE tape, but liquid is OK.
5/16" and 8 mm fittings have the same part number at BES.
Use copper olives.