Any 1/2" Left Hand Thread Plugs in UK?

[Phil]

mmm...

Its a good thing you didn't get one made then! I think we've all learnt something here..........

Happy boating.

 

[abrogard]

I reckon. And someone on another forum says the fitting looks like a 'barrel union' from the pipe fitting world. Finally an ID!

All the best to everyone. Especially Yorkshire. My family is from East Yorkshire.

 

[REDSAW]

donk!

 

[Dannypipe]

Yeah that does look like a 'barrel' plug. Barrel is just slang for steel pipe. Think I have a few of those plugs kicking around in my shed.

 

[tamz]

Better get yourself a brass plug. That iron one will rust quickly.

 

[SimonJohns]

Just had a thought. Have you ever heard of POLYMORPH

That may be a very quick and better fix

 

[abrogard]

Yep, brass plug.

I asked but our main nut&bolt supplier here didn't have anything but steel. And two inches the shortest. So I've got this great black steel thing sticking out of the hole at the moment. 🙂

I'll find one somewhere.

It is a 3/4" UNF. If this is a standard 'barrel union' type thing surely there's a standard plug for it?

The 1/2" plug would be a good candidate except it only goes in a little way and then gets difficult. The UNF goes in much better.

But I've been reading about threads. Maybe it is a pipe thread with that cunning trick of increasing the threads per inch so's the plug by design jams into the threads, creating a watertight fastening?

Maybe. Maybe not. The UNF wouldn't go in so well if that was the case, would it?

And rust, corrosion. Yes, good point. But what about the pipe itself? It is going to rust as quickly as any plug isn't it? I suppose it just means I must service the thing well after every use. WD40 I suppose. Is there something better?

 

[Joncpi]

Sorry but I had not looked at the photos you had attached when originally asking for help. But I now have. What someone has welded into your transom is almost certainly half of a pipe union.. If you were to clean it all up, which I would not advise, you would almost certainly find the larger hex. nut would be loose. It is intended to be screwed onto another "male" part in order to join two pipes together in such a way as they can be dismantled easily to remove say a valve or pump from the line. Anyway putting that aside I would say that your boat has had a 1/2" NPT pipe union welded into it. This is the most common thread type used in America for pipe threading. As you know they have a distinct aversion to using anything English or European e.g BSW & Metric threads for bolts or BSP for pipes so they came up with their own. ANC for bolts and NPT for pipework. So it looks as though who ever made your boat also used a pipe union from America. 1/2" NPT has an outside diameter of 0.840" compared to the 0.825" of a BSP thread.
I would now look on line and find a supplier of a 1/2" NPT brass or stainless plug. Try speedflow.com.au, not sure what material they are.

 

[abrogard]

Thank you for that. I will follow your suggestion. Including not cleaning up the area. I can see why you say it. Though it is going to have to be done sooner or later.

But later. We took the boat for an initial test launch yesterday and she's shipping water through the bottom somewhere. Probably loose or missing rivets. I'm pondering/gathering info on whether to abandon the rivetting and get it all welded up.

The UNF bolt we've got in there at the moment seemed to hold the water out okay, no seepage. I don't know what size it is, don't know how to measure it. My cheapo calipers seem to say it has 11/16th overall diameter across the top of the threads. It might be 3/4" UNF, I guess, fitting where a 1/2" BSP fits - and doing a better job of it.

I downloaded Speedflow's catalogue and I see they have a plug part number 932-12 which is 'npt 3/4' and I guess that might be what I need?

I will talk to them.

Thanks for your help.

regards,

ab

 

[REDSAW]

i was going to go into business building these type boats for fishing a couple of years ago.
got the jig gear drawings and everything, only to discover the 1051 alloy grade sheets were not available in anything bigger than 8 foot sheets!!!!?????????.

as for the seams leaking, you can get alloy sticks that you apply like brazing with a plumbing torch. i had been assured by the manufacturer of the rods they are approved for the application.

 

[abrogard]

By God, that's a good clue, Redsaw. It reminds me of something very much like that I looked into some years ago. I'll search it out again. If I remember I found it hiding in the guise of 'aluminium welding', which it isn't, really, because it is more like brazing, as you say.

That could be just the thing. I could fix the whole thing myself maybe.

I don't quite follow why the 8' sheets put an end to your project. Is it because it is not on to join sheets?

 

[Joncpi]

NPT 3/4" will be too big. (just over 1" OD) I think you need the 1/2" NPT plug (OD about 13/16") (same as 1/2" BSP)

 

[REDSAW]

yea, i wanted to build min 14' upto 18' boats with casting deck etc.
cant seem to be satisfied with a craft with a mid weakness by joining the sheets. one day?.

here is a link. - Durafix UK Ltd

 

[abrogard]

Thanks for the link. I see the Australian distributor and I think I'll get some rods and give it a try. I don't have an oxy set or oxy experience so I'll be using propane or butane - I hope it really works just as well with them?

Have you experience of it?

It is the thing I ran across some years ago. It seemed so good I couldn't believe it. Thought it must be some sort of a trick else it'd be in use everywhere. Can't help feeling somewhat the same now...

Perhaps it is in use everywhere....

Found two holes in the boat so far. Missing rivets. That might be enough to account for the amount of water it was taking on. Block them and I could be okay.

$50 for a set of these rods might be cheap for such a fix. Also long wanted to do some aluminium work and been bothered by the problem of fastening the stuff. This could be the answer...

🙂