Coke for Brazing

[Nick Clarke 3Participant @nickclarke3]

Is the use of coke for brazing with propane frowned upon nowadays? – in old magazines it was recommended for insulation and added general heat – I know it might add 'dirt' but surely that was always the case yet it appears to have been widely used – also steel does not get 'dirty' when hammer welding in a blacksmiths forge burning coke.

I am looking for information from those with experience in this area.

 

Edited By Nick Clarke 3 on 16/12/2022 17:40:24

[Nick Clarke 3Participant @nickclarke3]

[BazyleParticipant @bazyle]

Coke is what people with coal burners are encouraged to use now as it burns 'cleaner' ie less sulphur. With the greenies thinking that steel spontaneously appears without use of blast furnaces coke may become less available.

[JasonBModerator @jasonb]

I think a modern propane torch with the right size burner will put out more heat than an old paraffin blowlamp so the coke is not really needed. Add to that modern vermiculite insulating blocks and various blankets

[JellyParticipant @jelly]

It's pointless, putting vermiculite brick insulation in close around the part will result in far more heat going in than using coke, (unless you basically create a blacksmith's hearth, at which point, you don't really need the torch).

​

If you don't already have the torch, you can get a second hand Type 5 welding shank with tips, then buy a new propane mixer and single stage oxygen regulator all for less than the price of a decent "propane only" torch like the Sievert Promatic; 10L bottles of Oxygen are £50 rent free from Adams gas, and just like that you get a lot on heat on tap, enough that you need the insulation more as a backstop than a heat retention device.

Oxy-Propane is way easier to use for high heat-output tasks like brazing in the home workshop as you don't have the draw-off limits that a porta-pack of old would, so you can run a big "pepper-pot" or "rosebud" type nozzle off a little propane cylinder if required.

[Dave HalfordParticipant @davehalford22513]

Posted by Jelly on 16/12/2022 18:55:36:

It's pointless, putting vermiculite brick insulation in close around the part will result in far more heat going in than using coke, (unless you basically create a blacksmith's hearth, at which point, you don't really need the torch).

Sorry Jelly I don't get that, vermiculite bricks insulate as good as Rockwool, unlike old fashioned fire bricks or night storage heater bricks that soak up heat like a sponge.

cheapest bought on Ebay in a bulk lot of 20 you can make a large hearth to reflect the heat back into the job, with self tappers and kitchen worktop brackets to hold it together.

[Andrew TinsleyParticipant @andrewtinsley63637]

Coke is still a good idea for very large boilers (71/4" narrow gauge and larger). I used a coke bed with a small blower and a couple of large propane burners and did the silver soldering with help from an oxy-acetylene torch. You can't have too much heat with really big jobs.

I have read that coke can put impurities in the soldered joints as well as particulates. I have never had any problems , so a pinch of salt is required.

The difficulty I found was not getting overheated myself, I doubt, with my advancing years, that I could cope these days.

Andrew.

[JellyParticipant @jelly]

Posted by Bazyle on 16/12/2022 17:59:51:

Coke is what people with coal burners are encouraged to use now as it burns 'cleaner' ie less sulphur. With the greenies thinking that steel spontaneously appears without use of blast furnaces coke may become less available.

I mean, they would be right about that:

1) there are now techniques for producing steel which are reaching the point of commercial readiness which use direct hydrogen reduction of ores, at reduced temperatures to produce iron suitable as a feedstock for secondary steelmaking in an EAF; this doesn't require a blast furnace, and uses a lot less energy and raw materials.

2) blast furnaces produce pig iron, not steel,

and

3) blast furnaces don't need coke, they require a fuel which will yield a source of carbon (to produce CO) and heat.

Nippon Steel in Japan has several "Direct Melting System" plants which combine Gassification of municipal waste with primary steelmaking, using black-bag waste instead of coke, they have been doing so since 1979.

The Indians too have experimented with various types of Bio-Char and Waste products as alternative blast furnace fuels to some success.

​​

Interestingly waste tyres would be a shoe-in for it that kind of thing, were it not from the sulphur from vulcanising adversely affecting the pig-iron and driving up the cost of subsequent BOF steelmaking steps…

Which is the exact same reason that British Steel gave for being unable to use the coal from the proposed mine to which you're alluding at their Scunthope plant; whilst Tata is threatening to close Port Talbot entirely.

[Boiler BriParticipant @boilerbri]

I started my working life working for my brother in law – his farther and he were blacksmiths/farriers. The forge was run on coke and his dad used to weld things together when taken from the forge. The glow of the metal was white hot and the joints were great when they were finished, all hammered together.

I am not sure where you can get hold of coke now? It was hard stuff and took some lighting, but when it burned it was like nothing else, little or no smoke or fumes.

Days long gone.

Sorry for being nostalgic.

Bri

[JellyParticipant @jelly]

Posted by Boiler Bri on 16/12/2022 20:12:59:

I started my working life working for my brother in law – his farther and he were blacksmiths/farriers. The forge was run on coke and his dad used to weld things together when taken from the forge. The glow of the metal was white hot and the joints were great when they were finished, all hammered together.

I am not sure where you can get hold of coke now? It was hard stuff and took some lighting, but when it burned it was like nothing else, little or no smoke or fumes.

You can get it from most good coal merchants still, including some of the online ones although it's not cheap.

Coke forges are still favoured by a lot of "Artist Blacksmiths" partially because it's easier to control your heat, or even to get a differential heat on a workpiece, although the reason most of them mention explicitly is that it's the best heating medium to use for forge-welding in the manner you describe.

When I was still doing more heritage rail stuff the blacksmiths at the railway would use steam coal rather than buying coke specially, and had a very specific method of feeding the coals into the hearth, such that the volatiles would be driven off before it was fed into the burning zone, effectively coking the coal just before it was required.

[BazyleParticipant @bazyle]

Posted by Boiler Bri on 16/12/2022 20:12:59:

I am not sure where you can get hold of coke now?

Bri

Doesn't it come in plastic bags labelled 'coalite' from a garage any more? I only burn wood these days.

[Martin KyteParticipant @martinkyte99762]

I would suspect and I’m open to comments that coke was used in the early days of model boiler making because there was so much of it about (every town and many villages had a coal yard) and also paraffin blow lamps were the order of the day instead of gas torches. I would question the availability of vermiculite products in those days. As with many things in model engineering old ways persist because old books are still in use. I recognise that just because it’s an old technique doesn’t mean it’s wrong but there are new ways of working too. Sulphuric Acid was always used as a pickle after solver soldering mainly because of availability but there are better and safer pickles these days which are easier to dispose of and obtain and work just as well.

regards Martin

[JellyParticipant @jelly]

Posted by Bazyle on 16/12/2022 20:38:20:

Posted by Boiler Bri on 16/12/2022 20:12:59:

I am not sure where you can get hold of coke now?

Bri

Doesn't it come in plastic bags labelled 'coalite' from a garage any more? I only burn wood these days.

It's still about, but the bags are paper… However, Coalite is nothing more than a brand name now, you pay an extra £5-£10 a bag to have a familiar name on the same imported product.

 

From the 1980's onwards they weren't really a solid fuel company, but a chemicals company which happened to produce solid fuels as a by-product.

Unfortunately when they were bought by Anglo United in the mid 90's, the debt which funded the purchase proved too much, and a death spiral where all the profitable parts of the business were asset stripped off in a vain attempts to keep financing the debt meant that by 2002 they were all but insolvent, and the last plant at Bolsover closed for good in 2004.

In part their death was hastened by the decline of the agrochemicals sector in West Yorkshire, which was a key market for their products, but themselves had fallen victim to increasing levels of globalisation, and a resurgent indian chemical industry taking an interest the highly profitable substituted phenols market as a potential high value product.

Edited By Jelly on 16/12/2022 20:59:42

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