TO BRAZE OR NOT TO BRAZE

[firebird]

Hi

I know there has been a lot of discussion about this over the years so I apologise for re visiting the subject

I will be embarking on a Sweetpea later in the year and I will be building the boiler myself.

I have oxy propane gear in my workshop and having spent many years in the motor trade I am experienced in the use of oxy acetylene and sifbronze brazing.

A recent article in one of the model engineering magazines has sparked my interest. I have clipped the text. I hope I'm not falling foul of any copy right issues if so please remove the photo if needed.

With the ever increasing cost of silver solder I just wondered?




Any opinions on this would be appreciated

Cheers

Rich

[uuu]

Assuming you want to get your boiler club-certified, then you need to talk to the inspectors at your club - there's no point setting off in a direction they're not happy with.

Two points against what you're proposing:

The UK boiler test code does not comment on jointing other than silver solder and welding.

The original Sweet Pea design drawing may specify a jointing method. Departure from this could open you up to a challenge.

Good luck.

Wilf

[millman]

Sif-bronze is frowned upon because it is attacked by the sulphur in the coal, don’t know the nitty gritty details but someone will be along soon to explain the chemistry of it all. It will cost more in silver solder but you won’t have any problems from boiler inspectors.

[firebird]

I thought so

Just wondered if anyone had tried it

Cheers

Rich

[mbrown]

Copper welding has certainly been tried. There is a photo of a copper welded boiler in one issue of Don Young's magazine, Locomotives Large and Small. I think it was built by Steve Titley who was a friend of Don's from (IIRC) the Fareham club. Maybe someone on the forum from that neck of the woods will remember....

But others are absolutely right, the club boiler inspector is the final arbiter.

I found that one way to cope with the price of silver solder was to buy it in small batches over the months and years before starting the boiler - it spread the pain!

Malcolm

[Jo]

Talk to your boiler inspector who is going to give it a ticket. They can be fussy wotsits and there is nothing worse than building something perfectly safe to modern standards and finding they won't give you a ticket for it.

Jo

[borderer]

I don't think the article quoted is quite correct.

As I understand it, de-zincification is a result of electrolysis with the feed water under certain conditions. It will affect brass boiler fittings for example. Whether it affects brazed joints significantly is more complicated, because the brazing material changes chemically at brazing temperatures and forms a new alloy with the mating copper, so it is no longer "brass" as such.

The writer may be confusing Sifbronze with the self-fluxing Colphos which is indeed affected by some types of coal smoke, and should not be used in boilers.

[abby]

As per borderers comment the de-zincing is due to the steam not the gasses , this is why gunmetal fittings are used rather than brass.
Although there is a grade of Sifbronze that contains nickel and which may be resistant to the aforementioned de-zincification , Sifbronze does not penetrate a joint as does silver solder.
It is used to form an external fillet so it's actual application in a boiler would be quite restricted even if acceptable.
Dan.

[nickc]

Before reading the following please note:
1.This refers to published practice of up to 100 years ago, not what is acceptable today
2. As has been stated already it your Boiler Inspector who decides what is acceptable

BUT......
LBSC wrote up many boiler designs which were assembled in the main with brazing or later on with Sifbronze combined with silver solder. He did recommend silver solder for his design for Britannia, but suggested brazing for the throatplate/barrel joint to produce a fillet which would be missing from a silver soldered joint - is this important? - ask your boiler inspector.

Jack Austin-Walton designed his boiler for 'Twin Sisters' in the early 1950s without flanged plates and assembled using a self fluxing alloy which was described a couple of years later, in a reply to a querist in ME, as 'dangerous'

So the sound advice must be to listen to your club boiler guy and make it according to todays rules and ignore grandfather rights where these have proved to be no longer acceptable.

[jasonb]

You are more likely to get problems using Sil-Fos than you are Sif-bronze as the Phosphor content of the former is upto 15% and I believe that is what is attacked by Sulphur given off by coal, no problem if you are gas firing the boiler

If that is an article by Luker then ask him on ME Forum which he frequents..