propane brazing

[Nicholas FarrParticipant @nicholasfarr14254]

Posted by Vic on 27/11/2017 15:32:33:

When I worked in the motor trade many years ago we were told that it takes several hours for an Acetylene cylinder to explode if you get a blow back. I read a report some years back though where a cylinder exploded about 5 minutes after a blow back. Luckily no one was injured in the explosion but the building was damaged.

Hi, the state when Acetylene becomes explosive (apart from the obvious) is very unpredictable. To be reasonably sure you are safe with it, it is important to follow all the safety precautions with its use and that includes having well maintained equipment that is used with it. If there is Acetylene in a fire, there will be an automatic 200M exclusion zone around the fire, for at least 48 hours. It will only be banned from specific sites. In my day job we use Acetylene on very many sites, but it nearly always involves having to obtain a "hot work permit" before you start to use it, and all the precautions stated on the permit must be in place and adhered too.

Regards Nick.

[IanTParticipant @iant]

By the way Philip – another recent thread (brazing hearth) has reminded me of the importance of retaining/reflecting the 'heat' you do have available – as otherwise it will be much harder to get sufficient heat in place quickly.

I've mentioned the use of ceramic blanket in the other thread and you can see the ceramic I use in the background of the photo I've posted above – and it is folded around the work. Perhaps also of note – is that the part is supported on a piece of thin tin on edge – this helps circulate the heat underneath the work, doesn't conduct too much heat away and is less of a problem to remove (should an edge inadvertently brazed/soldered to the part).

Regards,

IanT

[the artfull-codgerParticipant @theartfull-codger]

Over the years I've gradally built up most of the sievert nozzles & a few torches & they've served me well from boilermaking to fabrication jobs both brazing & silver soldering,but since aquiring a flamefast brazing hearth it takes it too another level, they really are good,I also have a small "chance" air/gas torch for small jobs, it was for town gas & flamefast wanted £30 a torch to convert them,well that wasn't going to happen!! so I just tried them on propane & butane & they work fine except the regulators very sensitive but just as good as the town gas ones I used at school where I worked [Can't be spending money when we don't need too!!] they sometimes come up on ebay.

[Philip BurleyParticipant @philipburley44197]

Hello thanks every one for the advice , I am using a sievert 2941p burner and easyflo flux

[Clive Brown 1Participant @clivebrown1]

I was interested in the earlier tip from Dusty about mixing flux with meths. I don't do much silver soldering of steel, but when I do, I have reckoned that I get better results and better solder flow by putting the dry flux powder on the joint, rather than a water mix..

Sometimes more awkward to get it to stay in position though. I'll try meths next time.

[Alan VosParticipant @alanvos39612]

Posted by SillyOldDuffer on 27/11/2017 09:16:35:

I was intrigued by that too, but it does make sense depending on the Site. For example it's not allowed at Heathrow as per this Instruction.

That document states:

"If there are absolutely no practicable alternatives then acetylene may be used subject to the
approval of an “Acetylene Justification Report” by the Heathrow Fire Safety Team."

So, like all sensible prohibitions, it has a exception clause, with an approval process that is sufficiently stringent to deter the chancers.

AFAIR, the Home Secretary can still permit ownership of a handgun.

[larry PhelanParticipant @larryphelan54019]

I did that some 50 years ago,using two blowlamps,I was making a carrier for my motorbike at the time.

Took a while to get the heat up,used a few firebricks to help [all I had at the time ],but it did work.

[Brian HParticipant @brianh50089]

Many years ago, Rolls-Royce Aero specified surgical spirit to mix flux because it leaves no residue unlike meths.

The trick then is to gently heat the fluxed job so that the the surgical spirit catches fire and bakes the flux onto the parts being joined. The heat can then be turned up without the danger of the flux falling off, as happens with a water mix.

Brian

[Mark RandParticipant @markrand96270]

Posted by Brian Hutchings on 29/11/2017 17:54:07:

Many years ago, Rolls-Royce Aero specified surgical spirit to mix flux because it leaves no residue unlike meths.

Surgical spirit definitely does leave a residue. It's industrial spirit mixed with 2.5% castor oil. Industrial spirit is the one you'd want, That's ethanol with 5% methanol.

Regards

Mark 52 years a diabetic, injecting insulin

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