Drain-tap for fuel tank to replace large s/s nut. Any ideas?

Robert Wilson

Robert Wilson

Well-Known Member
Joined
23 May 2012
Messages
8,053
Location
Second Coast, Ross-shire, overlooking Gruinard Bay
Visit site
My diesel tank has a large (12mm? hex nut) as a drain plug which makes emptying the tank a pain; especially as the location prevents a five gallon receptacle being placed below it.
Ideally I'd like a properly sized drain-tap to screw straight in as a one-piece replacement, but as a last resort I could get the nut "drilled and tapped" then screw in a small-sized threaded drain tap into the nut. A hassle and probably costly to get an engineer to do it.

Any ideas where I can get large-diameter s/s drain taps?

TIA
 
Robert Wilson said:
My diesel tank has a large (12mm? hex nut) as a drain plug which makes emptying the tank a pain; especially as the location prevents a five gallon receptacle being placed below it.
Ideally I'd like a properly sized drain-tap to screw straight in as a one-piece replacement, but as a last resort I could get the nut "drilled and tapped" then screw in a small-sized threaded drain tap into the nut. A hassle and probably costly to get an engineer to do it.

Any ideas where I can get large-diameter s/s drain taps?

TIA
Click to expand...

Is that 12mm the thread size or the A/F of the nut.
 
ASAP Supplies have a fairly wide range of fittings.

It surely can't be a nut in the bottom of your tank, because nuts have holes in the middle. So the important question is whether it's a bolt, which will have metric or imperial (UNC?) threads, or a blanking plug which will almost certainly be BSP.

Plumbing fittings are almost always BSP, except a few items originating in the US which are NPT. So if what you have is a BSP blanking plug then an ordinary ball valve should screw straight in. If it really is just a bolt then you have a problem and might need to make something; hopefully not.

Tapping a hole is easy, and a single tap from eBay will be far cheaper than paying someone to do it.

I think you need to take the "nut" out, measure the thread, and post a photo.

Pete
 
If the tank is empty remove the plug (nut?) and take it to a plumber. He/she will almost certainly identify the thread and you can then get an appropriate drain tap ASAP or even the guy out in Lewis who supplies diesel filters and fittings who's name I forget but is much recommended.

Donald
 
Rogershaw said:
Is that 12mm the thread size or the A/F of the nut.
Click to expand...
I'm guessing the size of the threaded part

Aja said:
If the tank is empty remove the plug (nut?) and take it to a plumber. He/she will almost certainly identify the thread and you can then get an appropriate drain tap ASAP or even the guy out in Lewis who supplies diesel filters and fittings who's name I forget but is much recommended.

Donald
Click to expand...
The tank is full.......
As an inconvenient last resort I could pump-out the tank, which I will have to do anyway to check the bolt/thread size.

Finding a supplier is my first priority, then I can give them specifications when the tank is empty.
Thanks to you both.

PRV
Doh, I should have said bolt!!:o or plug.
That a blanking plug which will almost certainly be BSP is a useful hint.

I'll have to drain the tank, then seek fittings and an appropriate drain tap. I may even be lucky and fit one of the correct size and thread to screw in without further work. A 45 gallon oil drum tap may even do the job, at a very reasonable price.
fingers crossed crossed.

Thank you one and all.

​
 
Robert Wilson said:
...A 45 gallon oil drum tap may even do the job, at a very reasonable price...
Click to expand...

I wouldn't do that. A lot of drum taps are fairly "light duty" things, which is not what you want at the bottom of your fuel tank.

It's also a good idea to fit a blanking plug to the tap, for some extra security. The plug you take out might even do that job, if you're worried about prices!
 
The original drain plug on the tank in my Sadler had a very fine thread, not sure what. It was a brass plug in a stainless steel tank and had corroded due to water in the bottom of the tank. I drilled and tapped it for a BSP fitting.
 
Plenty of food for thought there!

I think in the interests of getting Khamsin in the water in a non-smelly condition and this side of August I'll do another test for water/gunge in the bottom of the tank (using a clear plastic tube etc) then syphon/pump all the rest of the diesel out overboard into a five gallon can on the drive.
Then next winter I'll attack the job, at leisure, starting with an almost empty tank!

Thanks folks, (especially the "don't use an oil-drum tap!)
 
OP: did you get around to this job and how did it go?

I'm ready to unscrew my blanking plug and replace it with a tap of some sort, pic below;

 
Take the plug out, go to your neast hydraulic trade counter and they will have a ball valve to fit, either imperial or metric
 
shoc said:
OP: did you get around to this job and how did it go?

I'm ready to unscrew my blanking plug and replace it with a tap of some sort, pic below;

Click to expand...
Prol 1/4" BSP, i have the same issue & am going to fit a 1/4" gas cock & a blanking the other end, this will be removed to operate the flow, the idea of a pump is a good one
 
You must log in or register to reply here.

Share this page

Top