Okay,
You've asked, now here are my answers:
A) SLEEVE: Multiple materials are acceptable for the sleeve. Multiple
Material choices have been suggested.
There'll be Pro's and Con's to each of the acceptable choices. So I'd like to be able to have a technical discussion on material selection.
That's why i'm asking the community here - what they now consider best practice. (Just as an example that my approach is rational - e.g - copper sleeve and cement don't always go well together - sometimes it eats away at the copper sleeve).
If I'm paying for the materials, and am presented with multiple options, I want to make an informed choice.
Straightforward.
Solid wall - no cavity, sleeve materials recommended:
"copper,
steel,
polyethylene (PE) or
polyvinyl chloride (PVC)"
Now - RGI (Yes not the standards used where I live):
RGI - Ireland - Sleeving Best Practice
Solidly recommends GRP Sleeving. Yet GRP is not mentioned here (01/07/23):
Pipe Sleeving - Institute of Gas Engineers UK
My follow up question would be - why?
Furthermore, in both bulletins managing fire-risk is clearly relevant. In that case - i'd like to understand how any plastic sleeving can be a recommended choice?
Worth discussing at least?
B) SEALANT: Two of the gas engineers (remember, I asked 3) said "silicone" the other said 'caulk'.
It was the third one that said specifically messaged me that it will be a:
"Non-setting gas impervious, intumescent sealant".
So why did the other two qualified gas engineers not mention this?
Only when probed, did i get the "...oh yeah, right. It needs to be fire and gas proof..".
Secondly, just as with any sealant product, there are good quality products and bad quality products. Simple.
Again - I (me) am paying for the material for work to be done on my own house.
So to me - it makes sense to ask, what product / brand seems to last through multiple seasons, over the long term. Whats considered a good quality option?
C) ANNULAR SPACE - each gas engineer did not know if there is a required sleeve diameter for 22mm gaspipe. As you can see, the Irish Bulletin has a table specifying the diameters of the sleeve vs the gaspipework. It is clear and specific.
All three (and I mean all three) engineers could not confirm the recommended specific sleeve diameters in England. They said (summarised) '...as long as it protects the pipe and gives some clearance'.
However : this table from the Irish bulletin DOES specifically give recommended diameters:
Again, these standards are not written for where I live, but for ireland.
And because three separate gas engineers could not help me with this aspect either - I felt It's fair to ask for assistance here, from the community.
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Now, you have repeatedly said ask your gas engineer.
I have asked three.
Multiple sleeve materials were suggested by each.
I have to choose one. So i've asked the community here, to contribute to the discussion.
Next, There are multiple sealant products available. No harm in asking for recommendations.
Thirdly, they could not give me the regs regarding relative sleeve diameter, (if such are specified in England).
So finally. The work is going to a gas engineer. They are going to be paid.
Clearly - I am just doing due diligence. They are each giving me different answers.
I'd simply like the work done right, to a very high standard - first time.
Now, please, can we discuss some of the points raised, so we as a community can all gain from the exploration of this subject.