Terrier Boiler

[IanmacParticipant @ianmac]

[IanmacParticipant @ianmac]

Some months ago I posted a question regarding what appeared to be cracking on some silver solder joints in a Terrier boiler I was building. This boiler failed and is now scrap. I have been advised that part of the problem was possibly due to the wrong grade of copper being used on part of the boiler, primarily the firebox shell..ie not C106 grade copper.

Very painfull on my wallet.

I am now looking at starting again and buying material ( Reeves did a Kit at £650 before Xmas it is now £1040!). Having had bad experiences with one metal supplier can I ask if anyone can recommend www. m-machine metals .co .uk ? (or anyone else?) for the supply of C106 copper.

I have to admit to being very foolish in as much as I bought the boiler kit and castings from E-bay. What appeared to be a bargain has been an expensive excercise + 2 wheel castings and one cylinder casting u/s indeed club opinion is that the cylinder castings were the wrong ones for the terrier.

Should know better at my age.

Ianmac

[D.A.GodleyParticipant @d-a-godley]

Ian; You will get the service and materials you require at a place in Birmingham called " John Keatley (Metals) Ltd". 33-35 Shadwell Street, B4 6HD tel 01212364300 fax 01212368576. http://www.johnkeatleymetals.com .

I assure you, I have no connection with them other than a very satisfied customer, as, I am sure ,you will be should you purchase from them.

regards,

David

[IanmacParticipant @ianmac]

Thanks David

Have asked them to quote for my maikitagain project

Ian

[julian atkinsParticipant @julianatkins58923]

hi ian,

john keatley doesnt list the correct tube required for the martin evans' terrier boiler barrel… 1/8" thick rather than 3/32", which will necessitate quite a few alterations at the smokebox and firebox end plus quite a bit extra heat required. there are quite a few improvements and alterations that can be incorporated in the original boiler design …pm me if you want further details.

cheers,

julian

Edited By julian atkins on 08/02/2013 10:03:36

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Ianmac ,

I have been advised that part of the problem was possibly due to the wrong grade of copper being used on part of the boiler, primarily the firebox shell..ie not C106 grade copper.

This sounds like the sort of thing that some plonker of a club expert would say . There are very good reasons for using the correct grade of copper but unless you've accidentaly used some really weird copper alloy cracking within the Silver Solder joint itself will have other origins .

Common causes :

(1) Too much or too little heat .

(2) Dirty job and / or inadequate flux .

(3) Parts moving relative to each other while cooling down .

I would advise you to look into matters a lot more before starting the new boiler otherwise following the original design and construction procedure for a second time may result in another failure .

My money would be on failure mode (3) .

Ask any questions you wish .

Regards ,

Michael Williams .

[nigel jones 5Participant @nigeljones5]

I am inclined to agree with Michael, I cant see silver solder cracking due to the copper. Are you sure cracking is the correct terminology – this implies that the solder had mated to both surfaces and then come apart – far more likely that it was a poor joint as items 1 & 2 above. If it had moved and come apart you wouldnt need to scrap the boiler as more heat and solder could easily have been applied. Come back to me on these points as this is an interesting one!

[nigel jones 5Participant @nigeljones5]

And…what thickness was the copper, what flux, what solder and how were you heating it?

[CuP AlloysParticipant @cupalloys]

Hi Ian,

The grade of copper does not cause the silver solder to crack. It is the effect of the blue zone of the flame acting on tough pitch copper that causes the copper to crack – called hydrogen embrittlement.

As described earlier it could be due to the components moving or are you building a crack into the back of the silver solder by not achieving full penetration of the solder into the joint.

Check joint gaps (0.1-0.15mm) joint length (3 – 4 X thickness of copper) and heating technique to promote the necessary capillary flow.

Also let everything cool down naturally. No quenching – as this can cause unnecessary thermal stresses.

regards

keith

[IanmacParticipant @ianmac]

Thanks Keith, I'll be contacting you re the SS for my new build

A few questions to answer

Julian, the boiler is a 7 1/4 terrier to Don youngs design barrel OD is 5 1/2 * 10 swg. All external copper is 3mm. Inner firebox is 2mm.

Michael, I have delved as deeply as I can into the reason(s) for my problem. Cutting the boiler open has revealed the main issue. I think it was due to inadequate riveting between the firebox tubeplate and outer cover.

The build notes on the boiler suggests no rivets in a firebox roof. I followed these build suggestions. First water test showed no leaks in the firebox but one superheater tube didnt look good so a reheat was done to rectify this. It was after this reheat that the problem began to appear with hairline cracks in the SS joint initially between the firebox roof to tubeplate joint.

As Fizzy suggests we tried a reheat/resolder to no avail and the problem was getting worse. From the cut open boiler one can see that the firebox roof and top corners were moving away from the tubeplate leaving a gap too wide for SS to fill. Further reheates compounded the problem as the outer wrapper was not returning to its original position and could not,due to the infill of solder in the wide joint. Water tests could have been compounding the issue further by allowind debris to flow into the cracks and acid not penetrating the cracks to remove it so 2 and 3 in Fizzy's suggestion are active.

Its been a steep learning curve.

Ianmac

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hello again Ianmac ,

(1) For future reference there are sometimes ways to repair problem joints of the type you describe .

(a) Bronze jack screws tightened under heat to close the gaps .

(b) Insertion of filler strips of copper under heat .

(c) Insertion of plain or threaded copper rods into drilled holes before heating .

(d) Use of brazing materials with gap filling capabilities and very local heating .

(e) Use of small areas of copper welding .

(2) For your new build .

(a) Put all the parts of the boiler together in units and then as a whole with mechanical fixings so that various parts can't move under heat . Rivets and screws are obvious but ledges , peened over bits , slightly expanded tubes and sacrificial temporary holding clamps and straps of copper all have uses . Have any screws and rivets prefluxed and put in fresh . Have screws and rivets just holding – not forced down hard .

(b) Use graduated melting point silver solders .

(c) Work out a proper order of work that makes assembly , access , heating and use of different silver solders most efective .

(c) Pay attention to minor details of design and construction . Here's just one example of this :

When using screws or rivets to hold a wrapper onto the flanges of a firebox tubeplate start drilling and fixing top centre and then work down each leg – left right left etc – to the bottoms . If you start instead at the bottoms of the legs and work up you will get a built in pucker in the wrapper as you near the top which will cause problems .

Regards ,

Michael Williams .

Edited By MICHAEL WILLIAMS on 10/02/2013 11:39:45

[IanmacParticipant @ianmac]

Thanks Michael

I did talk to others about alternatives to silver solder with better filing properties but was told that was largely a no no due to the material having already been exposed to silver solder.

For my rebuild I will follow the lines you suggest and go to a pro supplier of silver solder to get the graduated melting points. Im also considering using SS thin strip and flux inserted between mating surfaces prior to riveting.

I'm still trying to recover from the shock of the price of copper!. Its a minefield with some suppliers asking twice the price of other for individual sizes.

thanks again to all for their input,

I'll let you know when the new boiler is sucessfully completed

Ianmac

[DurhambuilderParticipant @durhambuilder]

Ian,

Copper prices do vary a lot, My 10swg x 5 1/2" barrel came from live steam models, £56 for a 13 inch length last June.

, one well known supplier wanted 3x that…..

[IanmacParticipant @ianmac]

Interesting buying copper, a wide variation in prices and responses to my enquiries

Found John Keatley Metals (recommended by Dave) to be excellent and will use them again without even trying elsewhere.

Likewise Cupalloys, they deliverd next day, I have started soldering and their combination of solder and flux works superbly.

One I will avoid is John Hood in Clydebank, they seem to be the only supplier in the Glasgow area but are part of a group based in Newcastle.

Ianmac

[SpringbokParticipant @springbok]

Ian

Cup Alloys I would trust implicitly and if you run into a prob Keith will help you
Bob.

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