Jointing stainless steel sheets

[leenowell]

Hi All,

I have some stainless steel sheets which are predrilled with a line of smal l holes down each side. I need to join them together but unfortunately to get the sizing correct, the overlap is too much to use the holes as they ar e. Also, I will need to seal/ mastic the joints using an external/ non-fla mable product as these sheets will form part of a chimney for an outdoor BB Q.

I was planning to use some of the holes along one edge, drill through the o verlapping sheet that is being joined to it and rivet/ bolt the 2 together. Then finding some sealant to seal the joints.

Searching around, I came across a few sites which actually suggest that sta inless steel glue is a better option - and from my perspective much less ha ssle.

Does anyone have any experience of this? Any other ideas?

Thanks in advance all.

Lee.

[newshound]

Not really enough information. What sort of loads will be applied to the joint? Sounds a bit like a kitchen application, is it hot or wet? This affects glue options. If you have two bits of stainless, both of which are firmly attached to something else with no possible relative movement between them, then a good double sided tape might provide both bonding and sealing. It would be advisable to ensure there is a perfect fit without tape/glue: don't rely on the adhesive to pull the parts together. If both bits are mounted on a single piece of wood, plywood, etc. I would consider drilling as you suggest, but putting suitable screws through both holes to fix the sheets down to the substrate. When I say suitable, I mean stainless and perhaps either dome headed or countersunk, if the sheet is thick enough to chamfer the holes.

[leenowell]

Great thanks for your reply. Sorry - I should have been a bit clearer...

The BBQ itself is made from concrete blocks which form the sides (and centr al support) of the sloping bit of the chimney. The sloping bit is made out of stainless steel sheets. In good old fashioned ASCII art is it a bit lik e this when looking from the front. ____________________ / / / / / / / / /_____/______/______/ [] [] [] [] [] [] [] [] []

The 3 vertical pieces are trying to represent the concrete supporting "wall s" which go front to back and the 3 sloping sheets above represent 3 overla pping (overlap will be at least 75mm) stainless steel sheets. Overall width of the structure is 1900mm. Stainless steel sheet is rigid with a 90 degr ee bend at one edge (which stops flexing) and are probably just less than 1 mm thick.

The sheets will be supported by and "glued" (ideally but could be screwed) to the concrete "walls" so once in place, there should be no lateral moveme nt. The only force I can see that the glue would need to counter is the te ndency for the sheets to want to seperate vertically. In theory, they may o f course be some wind which gets them to flex vertically.

I think the main thing the solution will have to deal with is the weather. In theory, being a chimney it could get hot but in my experience this is n egliable. Once set, the solution must be non-flamable in case a stray flame up hits it.

Thanks again for any help

Lee.

[Dave Plowman (News)]

I'd want to make sure any glue was up to the temperatures involved with a flue.

It's easy enough to weld SS - you might even have a local car exhaust place that could do it. Normal way is TIG - but some have achieved decent results with MIG.

[leenowell]

Any idea how much welding is likely to cost? I contacted a local sheet fab ricator to see how much they would charge to cut them to size and they want ed £5 per cut! The sheets themselves are only 900mm x 560mm...

[Chris Hogg]

I really don't see the need for the joints to be sealed as you suggest. Provided you have a reasonable overlap between the sheets, not much will penetrate the join. Consider pop rivets for joining the sheets. If you must seal the join, use a high-temperature silicone sealant, such as one of the ones advertised here

[newshound]

Thanks, I am still not quite clear about the geometry but since it will get quite warm I would rule out glue. Since only one side needs to be "good" I think I would simply go for pop riveting (but I have a big strong lazy tongs tool and a good stock of rivets). Stainless steel rivets would be best, but aluminium would probably be OK.

As Dave says in another post, welding might be best. Depends really on how much you are spending and how smart you want it to be.

[newshound]

With the substantial 75 mm overlap as posted elsewhere, high temperature silicone might well be sufficient as a glue *provided the individual sheets are also well supported, e.g. by being screwed to the blockwork*.

But I'd still go for pop riveting too.

[newshound]

Cutting stainless sheet is only easy with a big guillotine, and fabricators have the monopoly on them. (OK these days there is water jet and laser cutting too, but the kit is another order of magnitude more expensive).

Welding done by a skilled person with expensive kit will look very nice, but I don't see that you need it here.

[GB]

This is for an outdoor BBQ. They don't have to be gas-tight. I love pop rivets - so much result for so little effort. :)

[leenowell]

In terms of sealing the joints, I wasn't really too bothered about the smoke but more the rain getting in a soaking the BBQ. Cooking on a wet stone BBQ isn't fun....

[GB]

In that case, I suggest you think quite hard about the direction of the overlaps.

The very 1st minis that were sold had the welded joints in the floorpan facing forwards, so they scooped up any rain. These were only spot welded, remember. It did not take them very long to realise that this was a bad idea, but surely they could have worked that out ahead of time?

[Capitol]

I'd just use stainless self tapping screws on the overlap. A bit of smoke leakage isn't really going to matter IMO.

[JimK]

/I'd just use stainless self tapping screws on the overlap. A bit of smoke leakage isn't really going to matter IMO. /Q

Indeed, sense at last. If the bbq flue is working air will be sucked IN not smoke blown out....

But what do I know?

Jim K

[Scott M]

White exhaust goo (Holts Firegum in Halfords) would be an ideal sealant.

[harry]

Rain is not an issue. Make sure the horizontal overlaps are set to shed the water (like roof tiles) All you need is a few pop rivets, nuts and bolts or self tapping screws. All can be had in SS. Forget about glue it will soon let go when the metal expands.

[Peter Parry]

Do bear in mind that some stainless steel can be very difficult to drill, certainly with a hand held drill.

[RayL12]

Go to hardware store and buy a gun and pop rivets/washers. I few coins.

...Ray.