Securing gas pipes - do we use rubber?

[MagicalArmchair]

In my post here http://www.ybw.com/forums/showthread.php?426435-Ye-olde-gas-compression-joint-thread some months ago I mused about fitting the gas out in copper myself on Triola (I've fitted a Propex heater, and she only ever had a very dodgy long run of flexible rubber previously). I was given lots of very good advice (and some pretty sound warnings). I have since employed a raft of safety measures to head off my 'learning curve' (read potential incompetence) including an electronic gas sniffer wand, a bubble tester, a test point on the gas set up so I can call in the cavalry, leak testing fluid, a NASA gas alarm and a CO alarm too. Note, before I'm beaten around the head with the PBO 'elf and safety haddock, I will be getting the WHOLE install tested professionally, and each joint inspected when I'm done with a full description of my install methods and how each joint was constructed - my insurer has confirmed they are happy with this. The plan was to lay out the gas as below:

So, this week, in the beautiful weekend weather, I set about frowning at my new toys and fitted the bubble tester first and had some fun with my pipe bender and making up compression joints.

I had purchased plastic P clips to attach the gas pipe (at every 150mm) to the bulkhead (these: http://www.asap-supplies.com/plastic-pipe-clips-304953), and then noted if I needed to tweak the compression joints, this would leave the pipes too snug to the bulkhead. I also noted on ordering some more bits that there are rubber lined versions of these P clips (these: http://www.asap-supplies.com/rubber-lined-stainless-steel-pipe-clips-413758).

Questions:

• I plan to make up plywood shims to stand the copper off from the bulkheads where the fastenings attach. Sensible idea? How do others get around this and attach and stand off the copper from the bulkheads? Is there some other shim I could just buy rather than making them up in plywood? Praps a thick Nylon washer?
• Should I use the rubber lined version and spend the extra money? These would strike me as more vibration resistant and thus less likely to disturb the compression joints. That said, the bubble tester IS just screwed on to the bulkhead, so am I worried about nothing and should use the plastic P clips I already have (as pictured)?

 

[prv]

I have no particular expertise in gas fitting, but I'll weigh in anyway

I would have used the rubber-lined clips, I used lots of them for fuel and water plumbing in my engine bay last winter. But I reckon the plastic clips are ok.

Pete

 

[vyv_cox]

The gas pipe on my Sadler runs through short lengths (about one inch long) of rubber hose that are Sikaflexed to the hull sides. Although it has been perfectly satisfactory like that for the past 30 years I suppose there is a chance it might not be welcomed by a modern inspector. However, the same arrangement held on with P-clips should be OK.

 

[pvb]

Plastic clips will be fine.

Looking at the photo, do you have enough access to press the bubble tester's top down easily?

 

[MagicalArmchair]

Thanks all, I will stick with my plastic clips and save my ailing bank balance a few bob. I found these spacers too which will help stand the gas pipe off by 10mm from the bulkheads.

pvb, I made sure before I fastened the bubble tester in I could get push it down okay, it will require some cockpit locker yoga to get at it mind you once the gas locker is back in place!!

Vyv, on the section that runs along the hull to the back of the cooker, I am having a similar predicament of how to attach the pipe to the hull! (the long bit pictured in the below). I am going to bond a bit of 1 inch ply onto the inside of the hull with epoxy and put the p clip on that. That section of copper will be under the work surface of the galley and thus will be inaccessible without dismantling the galley :ambivalence:... the aft side of that bulkhead compression joint will also be under the work top... I am tempted to use one single length of pipe and get rid of that bulkhead joint (its only there as I've been told that's best practise when passing through a bulkhead...) and cut a bigger hole in the bulkhead to remove the chance of chafe.

 

[VicS]

The BSS shows various ways of protecting a pipe passing through a bulkhead but it is only really necessary with metal bulkheads and perhaps GRP. Wooden bulkheads are not seen as likely to cause chafe.

Bulkhead fittings are only needed where it is necessary to maintain water ( or gas) tightness. Even if/when they are used the land in the center can be bored out and the pipe passed through without cutting and introducing two potential leakage points.

You picture appears to show the bubble tester outside the gas bottle locker. It is usual to fit this inside the locker. I would position as many of the joints as possible ie those near the centre bottom of the first picture inside the locker too. Two pipes, without any joints, can then run from the locker, one to the galley and one to the space heater. They must of course exit the locker through bulkhead fittings or similar to maintain gas tightness of the locker but again by boring out the centre land of the fitting they need not be cut and rejoined.

 

[Topcat47]

Where my copper gas pipe passes through the bulkhead into the cabin, I used a proprietary bulkhead fitting. Once inside the boat, it had to pass through three GRP mini=bulkheads and where this occurred, I used plastic tubing to prevent chafe. I also doubled up on my pipe clips which were copper, sourced from Calor. The Gas fitter who signed off my work said it was well over the top compared with most new installations he'd seen. This was 10 years ago and the system still holds pressure on drop test. I've also not seen any sign of fretting around the penetration or the clips.

 

[pmagowan]

The idea of boring out the fitting is an interesting one I had not considered. I had been concerned regarding making a watertight bulkhead while having the least number of joints outside the gas locker as, in my experiences (especially with water plumbing) the joints are where the risk is and the pipe wearing through is unlikely.

 

[GrahamM376]

You picture appears to show the bubble tester outside the gas bottle locker. It is usual to fit this inside the locker.

+1 and remember the bubble tester will only show up leaks after it, not between it and the bottle.

 

[MagicalArmchair]

Ah cracking, thanks for the response, I'll ditch that bulkhead compression joint and make that section solid. That bulkhead is basically just galley furniture and not structural in any way.

Unfortunately there is no space in the gas locker to put the bubble tester, it only just has space for the two gas bottles. From the regulator to the bubble tester will be a short length of hose that I can test carefully and will have no compression joints etc to go wrong, so not quite fully BSS, a job for another day. I reckon next winter I'll fabricate up a new locker that fits propane bottles instead (cheaper and work to lower temps than my butane jobs) and move the bubble tester inside then.