GOK compression fittings on copper pipe

[sailoppopotamus]

I am in the process of updating my boat's LPG installation. There is a cooker in the galley. Copper pipe runs from the lazarette into the aft cabin, where the cooker shutoff valve is located (the cooker is on the other side of the bulkhead). I decided to replace the old shutoff valve which was showing signs of corrosion with a GOK stop valve.

It took me several hours to cut the old olive off the pipe, which I was proud to achieve with no damage to the pipe. I then installed the new valve. I did notice at the time that the instructions require the use of reinforcing sleeves when the compression fitting is used on copper pipe. Since these were not supplied with the valve, and the only place to source them in Greece seems to be through SVB (with the associated 2 week delay and 25 euro delivery charge), I went ahead and fitted the valve without them. I must admit I did not really follow GOK's instructions. I simply slid the compression olive on, hand tightened, and then tightened another 1 1/4 turn.

The system does not seem to leak. I tested with GOK's leak detection spray and the system pressurized to 70mbar. Yet, given the potential dangers of LPG, I'm worried that perhaps I've cut a corner here. On the other hand, the above point regarding the availability of the sleeves still applies, plus it means that I'll have to do the job all over again. Even if I again manage to not nick the pipe with my hacksaw, I'm worried that I won't be able to hammer in the reinforcing sleeve anyway given that the pipe is not new and in an awkward location.

Any opinions on how great a sin I've committed are welcome. I'd be grateful if we could skip the whole discussion about getting a certified professional to do this work -- to the best of my knowledge there is no such thing in Greece.

 

[VicS]

I am in the process of updating my boat's LPG installation. There is a cooker in the galley. Copper pipe runs from the lazarette into the aft cabin, where the cooker shutoff valve is located (the cooker is on the other side of the bulkhead). I decided to replace the old shutoff valve which was showing signs of corrosion with a GOK stop valve.

It took me several hours to cut the old olive off the pipe, which I was proud to achieve with no damage to the pipe. I then installed the new valve. I did notice at the time that the instructions require the use of reinforcing sleeves when the compression fitting is used on copper pipe. Since these were not supplied with the valve, and the only place to source them in Greece seems to be through SVB (with the associated 2 week delay and 25 euro delivery charge), I went ahead and fitted the valve without them. I must admit I did not really follow GOK's instructions. I simply slid the compression olive on, hand tightened, and then tightened another 1 1/4 turn.

The system does not seem to leak. I tested with GOK's leak detection spray and the system pressurized to 70mbar. Yet, given the potential dangers of LPG, I'm worried that perhaps I've cut a corner here. On the other hand, the above point regarding the availability of the sleeves still applies, plus it means that I'll have to do the job all over again. Even if I again manage to not nick the pipe with my hacksaw, I'm worried that I won't be able to hammer in the reinforcing sleeve anyway given that the pipe is not new and in an awkward location.

Any opinions on how great a sin I've committed are welcome. I'd be grateful if we could skip the whole discussion about getting a certified professional to do this work -- to the best of my knowledge there is no such thing in Greece.

I've never seen them mentioned before.

.

 

[vyv_cox]

I have used inner sleeves when fitting compression fittings to plastic pipe but never with copper. I have fitted many to copper without suffering leaks.

 

[sailoppopotamus]

Thanks to both of you, this is reassuring. Aside from checking with the leak detector spray, I've fitted a manometer in the locker and a gas detector below the valve in question so hopefully I will be able to catch a leak if it happens to materialize in the future. The fact that these reinforcement sleeves are not readily available, when local shops are otherwise relatively well stocked in GOK accessories, might be indicative that these are "nice to have" rather than strictly necessary. For what it's worth, they only require them with copper pipe, not stainless.

 

[VicS]

FYI

Gas Compression Fitting

 

[sailoppopotamus]

Thanks, that's very useful. I have not used any sealing compound, just a very light smear of oil on the threads of the coupling as recommended by GOK. GOK use brass olives, whereas Calor recommend copper ones. Not sure why GOK would specifically choose brass on products certified for marine use, but I imagine it can't be too wrong of a material if they are using it. Perhaps its less malleable, hence the recommendation for a reinforcement sleeve. The 2-step installation procedure described by GOK read like instructions intended for a laboratory setting, so I decided to forego it in favour of the procedure described in your link.

 

[Rappey]

the instructions require the use of reinforcing sleeves when the compression fitting is used on copper pipe

What are these reinforcement sleeves, where do they go ? Do they go inside the pipe? If so ive never come across an insert for copper pipe, only plastic.

 

[VicS]

What are these reinforcement sleeves, where do they go ? Do they go inside the pipe? If so ive never come across an insert for copper pipe, only plastic.

Yes

I looked at the BES site but could not find them. Google found them on BES' site and other places
BES.co.uk | Next Day Delivery On 15,000 + Plumbing Supplies

 

[B27]

I've seen them used in other industry, with annealed copper pipe.
Plumbing pipe is normally half hard?

 

[Daverw]

I think that’s the answer, for use with soft annealed copper tube, most we would use is hard drawn or semi hard so not needed

 

[sailoppopotamus]

Thanks to all for your input on this. For what it's worth I found this in the ISO 10239:2014 checklist for small craft LPG installations:

28. Only solid drawn copper or drawn stainless steel piping is used. Materials are galvanically compatible when connected.

49. Where cutting ring fittings are used in conjunction with copper piping, a brass insertion sleeve and brass cutting ring shall be fitted. All components match to avoid galvanic corrosion.

At any rate, my joint does not seem to leak so I'll leave it without a sleeve and test regularly. I have one more question for the forum.

My gimballed cooker (Dometic Sunlight) has an 8mm pipe inlet, which looks like it's made of stainless steel. On the other end, I have this GOK valve. It therefore seems that to connect the stove I need to slide a compression fitting like this onto the stove's inlet pipe, and connect it to the valve with a flexible rubber hose with 8mm (copper) pipe ends. My problem here is that GOK make two versions of the compression fitting, one out of brass and another out of stainless steel. Given that copper is going into one end of it, and stainless on the other, which would be more appropriate? I realize that either option raises questions of galvanic compatibility, possibly violating point 49 quoted above, which makes me wonder if there really is a practical way of adhering to the ISO standard.

I asked a local installer here and his advice was to not bother with compression fittings at all and just use a hose with a jubilee clip on it, which is certainly an easy way out.

 

[Daverw]

I don’t think galvanic corrosion should be an issue inside the boat as it needs water as well

 

[vyv_cox]

As Daverw says, the requirement makes little sense for a gas line inside the boat where there is no possibility of immersion.

In addition to that it is very common to swage stainless steel wire with copper ferrules on small boat rigging connections that clearly see plenty of seawater but last for years with no or very little corrosion.

 

[rogerthebodger]

28. Only solid drawn copper or drawn stainless steel piping is used. Materials are galvanically compatible when connected.


This also makes little sense as most tube these days is rolled and welded. Even normal galvanized and stainless tube gas tube is welded tube.

I used steel welded tube for my LPG line as the inside would not corrode as there would be no oxygen inside the tune and the outside was grit blasted and painted, joints welded, and pressure tested

 

[B27]

Thanks to all for your input on this. For what it's worth I found this in the ISO 10239:2014 checklist for small craft LPG installations:

49. Where cutting ring fittings are used in conjunction with copper piping, a brass insertion sleeve and brass cutting ring shall be fitted. All components match to avoid galvanic corrosion.

At any rate, my joint does not seem to leak so I'll leave it without a sleeve and test regularly. I have one more question for the forum.

My gimballed cooker (Dometic Sunlight) has an 8mm pipe inlet, which looks like it's made of stainless steel. On the other end, I have this GOK valve. It therefore seems that to connect the stove I need to slide a compression fitting like this onto the stove's inlet pipe, and connect it to the valve with a flexible rubber hose with 8mm (copper) pipe ends. My problem here is that GOK make two versions of the compression fitting, one out of brass and another out of stainless steel. Given that copper is going into one end of it, and stainless on the other, which would be more appropriate? I realize that either option raises questions of galvanic compatibility, possibly violating point 49 quoted above, which makes me wonder if there really is a practical way of adhering to the ISO standard.

I asked a local installer here and his advice was to not bother with compression fittings at all and just use a hose with a jubilee clip on it, which is certainly an easy way out.

A 'cutting ring fitting' is not the same as what we'd call a normal compression fitting with an olive.
Common in hydraulics etc at hundreds of psi and beyond.

Copper and stainless tend to be 'matched' enough to survive, aluminium is un-matched enough to be a problem.

 

[sailoppopotamus]

I too don't understand why galvanic corrosion would concern the authors of the standard, since to take place it would require an electrolyte. I'm glad that you all seem to agree I shouldn't worry about it.

As for ensuring an adequate seal, do you think that the brass or stainless fitting would be better given steel pipe on one end and copper on the other?

EDIT: I found another post on here with a similar question (Gas cooker hose tail fitting) where it is suggested that the inlet pipe might actually be plated steel. I need to inspect it more carefully....