PVC joints

[Speedy Builder5Participant @speedybuilder5]

If one was to make a rectangular sealed water reservoir of PVC sheet (its for a 5″ loco tender), would you glue the joints (Which glue) or invest in a hot air welding gun. I envisage joints to be but “welded’ with the odd boss for outlet/ filling cap etc.

I have used 100mm dia plumbing pipe using solvent glue etc for a tank, but I need more volume and use all available space in the tender and not sure that solvent glue would be the answer..

Bob

[Robert Atkinson 2Participant @robertatkinson2]

With close fitting joints solvent welding should be fine. If you want additional strength / integrity then when the butt welds have had a chance to fully “set” solvent weld an additional bead of plastic along the inside of the joints. Put the top on last obviously.

[noel shelleyParticipant @noelshelley55608]

I would use the idea but use ABS sheet, much tougher and less risk of shattering or cracking. Can be glued together. CT1 would be ideal as both sealer and joining – bit like silicone but much stronger.  Or plan B, get hold of an old copper tank, cut it up and soft solder what you need. Noel.

[DC31kParticipant @dc31k]

What are the rough dimensions of the tank?

It might be possible to make it seamless by heating up a sheet of material, draping it over a former and pressing on an outer mould.

In school D&T workshops, they have vacuum forming machines – heat the sheet, slide the heater out of the way, raise the buck and switch on Henry.

There may be companies who offer this as a service – you supply the buck; they have the machine.

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Does the total perimeter of the sides approximate the circumference of any off-the-shelf pipe? It would be easy to convert a circle to a rectangle. Then it would only need a lipped base to be welded in.

[Speedy Builder5Participant @speedybuilder5]

Rough dims:-  700mm x 250 x 120

Sheet thickness 3mm

[noel shelleyParticipant @noelshelley55608]

That will give you a working capacity of 4 gallons – that’s a big loco. Or a long run ? Noel.

[Nigel Graham 2Participant @nigelgraham2]

Perfectly viable approach.

I fabricated a fairly complicated motor-shield / splash-back for my Myford lathe, from 3mm PVC sheet.

I used standard plumbing-pipe solvent for the joints, but reinforced the corners with “angle-plastic” made by forming strips over the edge of a length of planed wood, softening the PVC with an electrician’s heat-gun.

No “welding”.

To improve air flow round the end of the motor I dished the adjacent panel by pressing the heat-softened plastic between two improvised plywood dies whose diameters happened to be suitable, using the bench-drill as an arbor-press.

(And no I would not use the drill as an arbor-press otherwise!)

[Speedy Builder5Participant @speedybuilder5]

Thanks for the ideas and comments. Unfortunately, copper tanks are a bit of a rarity over here, most are rolled steel and have been for some time.

Bob

[Nigel Graham 2Participant @nigelgraham2]

Some builders do use mild-steel for water-tanks, and coat their interiors with petrol-tank sealant.

An alternative might be to make the tank of steel with a screwed-on top plate (with rubber sealing strip), so the walls can be coated internally with fibre-glass and resin, using the kits sold for minor car-body repairs.

[blowlampParticipant @blowlamp]

Deleted.

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