Metal Tank Lining Question

[triangleforge]

I'm going to be using one of the tank liner products (probably POR-15, since that's what I'm most familiar with) on an old Norton Commado tank. It's pretty straightforward, but one thing has me a little puzzled.

There are two petcocks - one on either side of the tank, toward the back - and I'm trying to figure out how to prevent the liner mixture from filling up the threaded mounting bosses for them. I don't have a tap of anything close to the right size to chase the threads after the treatment, nor do I happen to have the correct size machine screws to plug them; it's a large-ish diameter, fine-threaded boss.

Here's my plan for the moment: Close the petcocks, fill the voids in them with melted wax and screw them back into place for the tank treatment. Unscrew them, drill or just cut out the skin of liner that will have formed over the openings, heat up the (all metal) petcocks to melt out the wax.

That said, it feels like kind of a kludge to do it that way, and I'm way open to better ideas.

[ducpainter]

I'd use corks and clean the threads with a q-tip and thinner after you drain.

No way I'd put those petcocks in it.

Any idea what thread it is?

[triangleforge]

Thanks, Nate - I hadn't thought of corks! Sounds like a perfect solution. It's been a while since I had the petcocks out, but I know there wasn't anything even close in my selection of oddball metric & SAE hardware. I suppose it could be Whitworth - in addition to the odd-dimensioned heads, did Whitworth fasteners have funky thread/pitch/diameters as well? i would imagine so.

[ducpainter]

Thanks, Nate - I hadn't thought of corks! Sounds like a perfect solution. It's been a while since I had the petcocks out, but I know there wasn't anything even close in my selection of oddball metric & SAE hardware. I suppose it could be Whitworth - in addition to the odd-dimensioned heads, did Whitworth fasteners have funky thread/pitch/diameters as well? i would imagine so.

Whitworth was pretty odd.

Good link here...http://shopswarf.orconhosting.net.nz/bsw.html

Could also be a straight pipe thread

Just make sure you clean the threads well before the POR sets up.

[Howie]

Could be British Standard Pipe Parallel thread (BSPP), British Standard Pipe Taper thread (BSPT) if the thread is tapered, SAE or, as Nate said, Whitworth.  This means finding a tap to clean the threads might be difficult.  Maybe someone on a Norton forum knows.

Nate, could Brad use a light coat of thin grease, teflon or another barrier on the threads before installing the cork to keep the POR 15 from bonding to the threads?

[Speeddog]

My Norton knowledge is next to non-existent, but I'd put my money on BSPP.

Dunno what the most effective barrier is for the POR-15.

[ducpainter]

Could be British Standard Pipe Parallel thread (BSPP), British Standard Pipe Taper thread (BSPT) if the thread is tapered, SAE or, as Nate said, Whitworth.  This means finding a tap to clean the threads might be difficult.  Maybe someone on a Norton forum knows.

Nate, could Brad use a light coat of thin grease, teflon or another barrier on the threads before installing the cork to keep the POR 15 from bonding to the threads?

If he's smart he'll use the petcock fittings to drain the POR and then just clean the threads with thinner and a q-tip. Then orient the tank so no more liquid drains out the fittings. He could use grease as a barrier, but I don't think it's necessary. If the threads are very fine and the petcocks are very soft aluminum I might be thinking differently.

The nice thing about POR is it is very thin and if you get it right away it cleans up easily. POR cures from absorption of moisture. It will be several hours before anything happens where Brad lives. He'll have time for clean up.

[triangleforge]

So I go away for a couple of days and suddenly everyone's talking about me in the third person, like a pet or a little kid? At least you're not spelling things out like T-R-E-A-T or W-A-L-K so I don't catch on. Oh, wait...  

Seriously, thanks - I think I've got a plan of action now.  

[speedknot]

Hey TF.  I did my CB360 tank in the KBS Coating.  I'm not sure what your tank set up looks like but it sounds like the petcock threads are internal?  Formulating a wax plug might be an idea but youll have to remove whatever is in there to drain the excess coating.  If the petcocks are going to be replaced then is it possible to just leave them in there and remove them at drain time?  The threads on the petcock port on my CB360 are the male external type.  I had plans on replacing the petcock anyway so I just left the old one in while I did the tilt coat process and removed it upon draining.  The stuff stays pretty liquity for a while so you can wipe it out of the areas you dont want it to be.  The KBS is fantastic stuff.  Not sure what chemicals POR uses but the KBS product went on and dried like a heavy duty industrial coating.  No bullshit.