Steel conduit wall thickness

[Marvo]

I'm hoping a few of the older members might remember this. I need to know what the standard wall thickness used to be for the very old type threaded steel conduit (20 and 25mm equivalents). I'm guessing the diameter and wall thickness was in imperial sizes so I also need to know what the newfandangled metric equivalent steel tube sizes would be. Also for good measure does anyone remember what the thread specifications were? Was it taper threads or parallel and any idea of thread pitch or TPI specs would be great.

Thanks in advance.

 

[GLENNSPARK]

1/8".....which would be the equivelant to 3mm....
but you need to remember that its the bore on british thats measured....OD on metric....hense the `strange` sizes for BSP taps n dies...but thats pipe sizes anyway......
it may not be the case for conny....

 

[Engineer54]

God your asking something now!! lol!! I can't remember the wall thickness of either the standard or heavy duty screwed conduits. I can tell you that they weren't tapered threads though, that's the American standard for their conduit!!

There are converter's available (or used to be) from the old 3/4''/1'' to metric 20mm /25'' though. And i guess for other lager sizes too...

 

[GLENNSPARK]

God your asking something now!! lol!! I can't remember the wall thickness of either the standard or heavy duty screwed conduits. I can tell you that they weren't tapered threads though, that's the American standard for their conduit!!

no...they will have been a BSP threadform.....

 

[Engineer54]

no...they will have been a BSP threadform.....

No to What?? lol!!

 

[telectrix]

you might find some data here:
Maryland Metrics: Technical Page Index

- - - Updated - - -

you might find some data here:
http://metric-metals.com/techindex.htm

 

[GLENNSPARK]

No to What?? lol!!

tapered threads....their gas threads them....

 

[Engineer54]

tapered threads....their gas threads them....

The Yanks use a tapered type thread on conduits and fittings. Certainly on they're seamless H/D conduits...

 

[telectrix]

they do that so there's a chance of it fitting somewhere up the thread.

 

[GLENNSPARK]

The Yanks use a tapered type thread on conduits and fittings. Certainly on they're seamless H/D conduits...

fair enough.....i just know that tapered threadforms are used on gas fittings.....
you can get BSP tapered n all...
the americans use NPT...national pipe thread...

 

[Marvo]

they do that so there's a chance of it fitting somewhere up the thread.

Lol, that might be tongue in cheek but it's probably the truth

I'm pretty sure the installation that's going to be giving me headaches will have been done to old British Standards rather than US standards. The entire installation is threaded. I have a threading machine but I'm concerned I might not have the tooling to cut the old threads, especially if they were tapered which thankfully it sounds like they won't be. I'll need to sourc some new pipework and I wasn't sure whether I'll need to make up some adaptor couplings and do the new stuff in metric threads or whether I can just continue with the original threads on the new pipe but wall thickness could be critical.

I'd rather use the original threads on the new installation because many of the very old light fitting and other fixtures screw directly on to the conduit tube.

 

[telectrix]

why not fit adaptors to the imperial conduit then do your new work in metric?

 

[GLENNSPARK]

why not fit adaptors to the imperial conduit then do your new work in metric?

or have yousen a little sesh with the stick plant.....
weld on a bit of metric....then run a thread on that.....

 

[Marvo]

Adapters are an option but there's other complications with fitments that we'll need to reuse that screw directly on to the old conduits threads.

 

[Silly Sausage]

Time to get your Thread Gauges out!