Bodging a leaking diesel tank

[MrFerrous]

I've got a 1000 litre diesel storage tank in a barn which is connected to a system of hoses. The hoses are connected to the tank via some 1/2" BSP connectors a bit like these

think this kind of connector is intended to seal on its threads rather than by pressing against a washer. Although PTFE tape was applied to the thread when assembled, diesel is slowly leaking from the connectors, at a rate of a few CCs per day. The leakage is definitely from the thread rather than the hose-barb.

I know the correct answer is "drain the hoses, and reassemble the connectors with a better thread sealant", but disassembling it would be inconvenient, so I'm looking for a bodge.

I've tried wiping all the visible diesel from the exposed threads and smearing them with blue Hylomar, but that started leaking before the Hylomar fully cured.

I guess what I'm looking for is some kind of fast-setting silicone sealant that is tolerant of small amounts of diesel while setting. Ideally I'd like something that won't set completely hard, because I might want to dissamble in future. Perhaps some kind of 2-part sealant, or one that has to be heated before it is applied?

Any suggestions?

[Dave Liquorice]

"A bit like these" or "the same as these". You say BSP but the page you link to is BSPT, ie taper threaded. Taper thread should seal on the threads assuming they are fitting into a suitable depth boss on the tank.

BSP (parallel) will be difficult if not impossible to seal on the thread.

[MuddyMike]

> I think this kind of connector is intended to seal on its threads rather

Unless someone comes up with some magic sealant I think you are on a hiding to nothing. The pressure of the leak will simply push away any sealant before it even starts to set. As for getting something to stick well to a surface covered in diesel, I don't think so but am happy to be corrected.

If they are BSPT then the thread is tapered and should seal if tightened a little more. If not my plan would be to unscrew the connector a couple of threads and quickly wrap a few layers of PTFE as close as possible to the union and then re tighten. If the pressure of the diesel is not too great you will only increase the leak to a fast drip whilst doing it. This of course assumes the fitting will undo and not shear off!

Mike

[MrFerrous]

To supply some more detail, the leaks are occuring where some of these connectors:

into one of these pumps: think the person who assembled the connections (not actually me) used thick "gas" PTFE tape rather than the thinner plumbing type, I don't know if that might be a factor.

[Andy Dingley]

Oyltite stick. Found wherever old farm machinery goes to die.

However I've no idea how well it adheres to plastic pipework.

[Onetap]

PTFE is no good for diesel, as I discovered after using it on a gas- oil connection. Look on

for something more suitable.

Then drain and remake the joint. ;-)

[Tim Downie]

I would just make up a clean "drip catcher" so that you can recycle the leaking oil back to the tank. Once it's near empty, fix the problem properly.

I suspect trying to making anything stick to diesel oil coated metal isn't likely to work.

Tim

[Weatherlawyer]

BP got away with blaming esquimaux for decades before the US government made them replace all their Alaskan pipework. Apparently there are some bacteria that thrive in hostile conditions, living in oil and eating metals.

There is no such a thing as a perfect seal. One that eats Canadian clubbers comes pretty close though.

[Jim White]

I used to install petrol and diesel pumps, and we used a jointing compound called Heldite - a bit like Green Hermatite. Google it. As others have noted, the first item on the tank should be a gate valve, preferably followed by a strainer filter. Oh, and by the way, any pipe fittings should be black iron, as diesel doesn't like galvanised pipe.

-- Jim White Wimbledon London England I will not sell school property

[The Medway Handyman]

Surely PTFE is completely chemically inert?

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember harry saying something like:

Make mine a Ginsters.

[Dave]

> I think this kind of connector is intended to seal on its threads rather

There used to be a product called 'Petropatch' Would that work with diesel?

Dave