Fire In The Foundry

[awemawson]

Early this afternoon I melted a bit of aluminium alloy - just pouring to ingot - less than a kilogram.

For some (very fortunate) reason I decided this evening to weigh it - and unlocking the workshop was greeted by a pungent smell. Got stronger as I went through the fire doors into the foundry - somethings burning.

Now admittedly there was a bit of a splash as I poured the ingot, but nothing exceptional - but here we are  with the floor channel Acco drain totally burnt out, the timber of a stout castered dolly that was in the foundry still gently crackling with red hot embers, and charring round the fire extinguiher and up towards the only bit of timber wall cladding.

This could have been bad - and I mean REALLY bad - if that bit of timber clad wall had gone up in flames the whole back wall of my workshop could have burnt 

Oddly there was a floor mop and bucket totally melted and burnt out that I'd used to mop up antifreeze spills from recently replacing all the furnace coolant - had it dried and spontaneously combusted ? I don't think so but have no proof - I THINK what happened was a splash of molten aluminium had got into the (dry) floor drain channel which probably had quite a bit of fluff in it, and  as it burnt along it's length took the rest with it.

But heck - this is a rude awakening.

I've moved the still glowing bits of the dolly outside and doused it with a few buckets of water, and sprayed every where that there has been charring with a hand pump water spray, and will come back in an hour and re-check everything.

[vintageandclassicrepairs]

Hi Andrew,
A close encounter indeed  Luckily you went back to the foundry before it got a real hold

Where I worked there was a "Hot Work"  safety procedure, where the site had to be inspected several times in the first hour after the work had been completed,
I still follow these guidelines at my home workshop after welding and the likes

We had a field fire next to our house last August, where the barley stubble and big round bales went up due to spark from a tractor exhaust (we think).. It burned to within 6-10 ft from the house taking most of the boundary hedge with it. Without the Fire Brigade crews arriving I believe we would have lost the house
It frightened the sh*t out of me

John

[awemawson]

John, I’ve always done the ‘check after half a hour’ thing after welding, grinding and especially casting, and did so this time. I suspect something was smouldering in the Acco  drain channel but I didn’t smell it as the foundry ventilation is very good, some would say excessive! The Big Six fibre cement cladding just overlay the dwarf walls with big gaps at each corrugation

[awemawson]

So - morning after the night before - clean up time 

Oh boy the place STINKS of fire. So a quick survey of the damage tells me:

A/ The Dolly has lost three out of four castor and it's surface - i have spare of the castors & wood

B/ The Fire Extinguisher still works and has cleaned up well but will be relegated to being a source of CO2 for Sodium Silicate setting

C/ The Steel fire door has cleaned up remarkably well apart from burnt paint where the seat of the fire was.

D/ The poor old Kiln is hopping on three out of four castors, one having been lost to fire but it's control panel cleaned up OK

E/ The floor drain duct must have been the plastic variety with ribs set in the concrete, as there is only the vestigial traces of the ribs left - I will fill the channel with concrete as it was redundant anyway dating from before the foundry building was erected

It could have been so much worse - I need to plan how to replace the small area of feather board cladding that dates from when it was the outside of the building - it's only five foot by six foot - so either steel sheets that I may already have - or fibre cement board to replace it.

Then I need to have a good think about smoke alarms with a remote siren that can reach the house - there are some that WiFi to your phone but it's adds another level of complexity to go wrong.

. . . I stink of fire and need a shower 

[awemawson]

Well that unused drain channel isn't going to cause more problems - I filled it with cement this morning !

[tom osselton]

That looks much better!

[Muzzerboy]

I have several Aico smoke / heat detectors in my home, including heat detector in the workshop. These are interconnected wirelessly, so if one goes off, they all do. There's also a simple wireless terminal for silencing, testing and identifying them. Not at all expensive and didn't require hard wiring. Most are mains backed but with batteries so they work during loss of power. Unless you are a long way away from your workshop, this would work for you. Beyond that, two or more of them can be wired together to make the last leg to the house.

[vtsteam]

I have visions of you stopping the blower, the tuyers heating up and the plastic fittings dribbling down 

This because I used plastic air hose leading to steel pipe tuyeres on an outdoor furnace which was set on a sand base.

I would have never placed a furnace indoors adjacent to a covered plastic drain.

I'm sorry this happened to you Andrew, glad no more damage ensued. I don't think it's funny.

Perhaps you might also rethink  the occasional bemused criticisms of others practices here, in light of present experience.

[awemawson]

Kiln got re-mounted on new castors so at least it's now movable again without the pallet truck.

The fire door got a bit of a clean up and splash of paint to keep the rust at bay, and the new cement infill got a rough going over with some ancient floor paint to keep the dust at bay - all a bit rough and ready but that's all it needs in this application.

Not decided what to do about the small area of original wall cladding - I'll almost certainly replace it with something non-combustible, but I'm looking into fire proof squirty foams to seal whatever edges remain.

[awemawson]

This afternoon I started removing the small area of timber cladding that originates from when this wall was the external wall of a barn.

I attacked the easy (right hand) side first - this is backed by a 'new' 100 mm cement block wall so once stripped the wall itself is sufficiently fireproof. Where it joins the roof, and where pierced for services will need quite a bit of detailing but at least it's a start.

Surprisingly it produced a generous wheelbarrow of timber which is burning in a (hopefully) controlled manner in my incinerator. Better there than up the side of my workshop !

The left hand side will be a bit more complicated, as the shiplap continues through from the outer rear wall of the workshop and each plank is going to have to be sawn to length in a bit of a cramped corner. But that's for another day . .

[awemawson]

This morning I started stripping off the left hand side of the timber cladding. It's a very awkward corner, and if I wasn't left handed would be pretty well impossible - luckily I am !

The bulk is now removed and the finessing begins - all those plank ends need trimming in situ back to the wall which should be possible with the Fein Multi-tool but it only just gets in the space behind that RSJ.

Up at roof level the construction gets complicated to say the least - this is where three buildings and their roofs come together having been built at different times, and not surprisingly is where I have had an ongoing persistent leak when the wind is in the wrong direction.

I'm not as flexible as I'd like at the moment so enough for just now - but at least it's a bit of progress. The blue vapour barrier was fixed to the unclad original barn that forms my workshop, and once clad with shiplap had foam insulation sprayed from the inside. That foam, though not particularly inflammable, is not fireproof but it's not really feasible to remove it - I will probable over clad it with fire rated fibre cement sheeting, and seal the edges with fire rated expanded foam.

[awemawson]

So after what seems a ridiculous amount of time I eventually got the rest of the original timber shiplap cladding cut back and was able to start boxing in the exposed inner wall that has my workshop on the other side.

So what to use to box it in ? I happened to have two sheets of Knauf Aquapanel that is intended as a tile backer board. Knauf claim it to be fire resistant as well as suitable for damp conditions. A quick test with a propane torch showed that indeed it was fireproof, and as this corner is the one with the irritation of occasional  roof leak it seemed be the stuff to use!

The placing of the original batons wasn't the ideal spacing but the wall construction didn't allow of change so they were re-used. Firstly running a 2" border round the periphery I then cut the lower panel to size (9" diamond saw and loads of dust!

The second panel wasn't so simple having the slope of the roof and some odd cut outs so I first made a plywood template before slicing up the remaining sheet of Aqualpanel.

The complex construction of this corner offered a few challenges - the welding shop next door has a 100 mm block cavity wall spaced off a similar shiplap wall that I'd had built years ago to prevent fires, but this cavity was exposed to the foundry where the RSJ's had been welded and bolted to form the new foundry building. Very little to fix cladding to here and I resorted to bending up a metal box structure to make the necessary seals.

[awemawson]

Then it was a case of squirting fireproof expanding foam into all the joints. I hate applying this stuff! One of the main problems is that the can has to be inverted when spraying, and if you are filling the roof / wall joint this is neigh on impossible. For the first can I added a pipe extension but up in that tight space, on a ladder and reaching round the RSJ it was never going to go smoothly !

First can did about 3/4 of the job, and I had intended to trim the surplus foam back and make good missing bits with the second can. Despite claims as to 'time to trim' on the can they weren't realised so I carried on as best I could after a few hours filling in the missing bits.

As always in this situation far too much ends up on the floor - and as it finally all expands and set much will have to be trimmed back for tidiness - I guess somewhat less than the volume of one can will actually remain in the joints !

So apart from trimming the foam, I still have to re-fix the electrics and scrape mounds of set foam off the floor then I think it's 'job done'.

. . . did I tell you that I hate expanding foam !

[awemawson]

So you'll be pleased no doubt to hear that this long drawn out mini project is finished. Several days ago I trimmed back the 'fireproof' expanding foam and re-routed the cables for the light switch and pair of twin sockets.

These cables are 'Hi-Tuff' circular with an 11 mm diameter outer sheath and I had no suitable cable clips for them - clips ordered and at last they arrived this morning and were fitted. Previously these cables were routed (clipless) behind the shiplap cladding that I've removed.

So foundry now back in use - in fact I did a couple of melts yesterday one of which produced an amusing incident. I was reducing an old rotating washing spinner to ingot - it comprised channel extrusions and the main central tube that sits in a hole in the lawn. Extrusions went in first to produce a nice molten puddle, and then a 12" length of the 2" tube. As I reached down to get another tube length from my bucket the first one was ejected onto the floor 

Trying again sure enough the tube was levitated ! No big issue - I just held it down with my poker until it melted.

I assume that the tube being a complete circle had sufficient magnetic field induced in it to react with the furnace field and hence levitate - it WAS a bit of a surprise !

For neatness I do still need to shorten the mains cables for the roller shutter door and emergency light fitting that plug into that upper double 13A socket but that's trivial.

[tom osselton]

I would not have thought that it could levitate like that!