Copper for boilers

[Sam Longley 1Participant @samlongley1]

[Sam Longley 1Participant @samlongley1]

The only good thing to come out of my visit to the MEX at Brooklands was my chat to the chap with the 3 inch scale Marshall just inside the gate. I could have spent all day talking to him & watching his engine create steam like nothing on earth.

Among other things we got talking about copper for boilers & he started lecturing me on the difference in effect between cold air & hot steam at the same pressures. Then i mentioned a PYRTE boiler & said I could source 1.5 metres of 4 inch copper pipe from a heating engineer for not much more than I could buy 12 inches from a model supplier. He immediately went into a rant about types of copper warning me that I might be making a big mistake. I was unable to stop & talk for long, so want to check with the experts because I can get all the copper i need – including some for the end plates -from a 1.5 m length. But would it be the wrong sort of copper as he suggested it might, or was he being a bit paranoid? I could effectively save some dough & have enough for several false attempts which i will probably need , being first effort.

[Brian HParticipant @brianh50089]

As I understand it there is no specific requirement for copper to be to a certain standard but C101 for sheet and C106 for tube seem to be the most used and also seem to be the easiest to obtain.

Is there a way of comparing these specs with the specs for the copper that you can obtain?

[JasonBModerator @jasonb]

A good make like Wednesbury's black lable is made from CW024A which is the same as the C106 that should be used for boilers, other imported stuff may not be quite as good. Depending on what table the plumbing pipe is then the wall thickness may be a bit low for a 4" boiler. The 1.5mm stuff is most commonly used on plumbing which is 1.5mm wall but I would have thought you should be looking closer to 2.5mm wall on that sort of diameter and certainly on teh plates if you plan to flatten out the tube. Also be aware plumbing tube will be 108mm OD and not 4" (102mm)

At the end of the day talk to whoever will be certifying the boiler before you put your hand in your pocket.

[Sam Longley 1Participant @samlongley1]

Now Jason has raised it I see that the PYRTE design calls for 1.5mm for the tube & 2.5mm for the end plates.

As for the diameter , yes I had already picked that up, but most of the dimensions are variable on this model so i think I can work with the extra 4mm on diameter.

I am not a member of a club so knowing who is going to test the boiler is going to be a problem. Seems pointless joining a club now to get advice for something that might take a while before it is ready to test.

As far as I am aware the nearest club is in Chelmsford. Not sure how they will view someone who asks to join just to get a test done ( assuming they have a qualified tester) then disappears. Not very favourably I imagine. Cannot say I would blame them!!!

[JasonBModerator @jasonb]

Most club inspectors would also like to see the boiler at various stages during construction not just be presented with it when complete.

Although the size difference is only small it is not just a physical change which as you say on something like the PYRTE is not critical but it will also affect boiler calculations which if they were a bit on the tight side will be stretched even further, the calculations use diameter and areas of end plates both of which will now be higher. So again a good reason to talk things through first. One inspector may consider it not far enough from the original spec to worry, another may want to see a full set of calculations to show that teh changes are within what is considered safe.

I don't want to sound like I am puting a damper on things but I feel it is better to get things sorted before spending a lot of time and money on a boiler that you may then have difficulty or reluctance to certify.

[Keith HaleParticipant @keithhale68713]

As suggested by Brian use C101 and C106.. The reason is that these grades are oxygen free and are not subject to the risk of "hydrogen embrittlement"

Oxygen exists in the copper as copper oxide. If the brazing torch gets too close to the work the flame takes on reducing characterstics. The flame reduces the oxide to metal and creates steam. The exit for this steam is via the grain boundaries. The associated stress cracks the copper.

Cheaper grades of copper may also contain lead. Silver solder does not like lead. It is diissolved by the filler metal and alters ithe alloys' flow characteristics. Penetration of the filler metal may be compromised.

You pays your money and takes your choice

Keith

[KWILParticipant @kwil]

Sam,

The advice from Keith (Cup Alloys1) comes from long experience and expertise, you should heed it closely.

[Brian HParticipant @brianh50089]

I would suggest that joining a club is money well spent as the boiler test facilities alone would make it worth while. Added to that is the knowledge and help available from the club boiler testers as well as the chance to see what other club members think about all other aspects of modelling.

There is no need to attend every meeting but often the talks, visits to other clubs etc and insurance advice are all well worth considering.

[Sam Longley 1Participant @samlongley1]

The problem I have is obtaining the 4 inch copper tube ( 12 inches plus 3 inches plus the end caps) at a reasonable price. It seems from this forum that the suggested supplier ( MACC) is not supplying at present so i am stuck for an economical source < Not that MACC is what one would call "economic"

So who are the next cheapest down the line ? someone must be in the know!!!

Edited By Sam Longley 1 on 17/09/2016 12:10:39

[KWILParticipant @kwil]

Just looked at MACC site, where does it say not available?

Edited By KWIL on 17/09/2016 12:16:45

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by Sam Longley 1 on 17/09/2016 12:10:17:

So who are the next cheapest down the line ? someone must be in the know!!!

Have a look at Blackgates. Their prices look similar to MACC.

Kwil, I believe people have had difficulty getting a response from MACC lately.

Edited By Roderick Jenkins on 17/09/2016 12:42:54

[DustyParticipant @dusty]

Sam Building a boiler is never cheap, if you try to cut corners it will, I venture to suggest cost you in the long run. I might be wrong, but I do not think plumbing 'pipe' is solid drawn. Remember you are building a potential bomb if you get it wrong. I know that the Chelmsford Club do have boiler testing facilities and being a member of a club has lots of advantages as has been pointed out. None of us like paying more than we need to, but in this instance I would say pay up and feel confident that you are using the right materials. The next thing will be boiler fittings, brass is an absolute no no bronze or gunmetal, and they are expensive as well.

[Brendan CorcoranParticipant @brendancorcoran61081]

Re MACC models, they are vey much on the scene and their service is impeccable

I made a n order last week after four in the afternoon and it arrived the next morning I have no connection whatsoever with them

Brendan

[Sam Longley 1Participant @samlongley1]

Actually i searched for the thread & realise that it was an old thread so I stand corrected & apologies to MACC

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