Taptite - questions.

[hotrodder]

Cheers. I'm guessing the tube is currently 5/8" 14swg (15.88mm x 2.03mm)? Are you using ERW, CEW (aka DOM) or CFS 3 (aka CDS)? I'm guessing ERW as CDS should be easy to source in 15.88 x 2.64mm. CDS is obviously more spendy than ERW though with CEW somewhere inbetween

Cold Drawn ERW Tube (CEW) | Hub Le Bas will give you sizes of CEW available (not so many stockholders carry CEW though), similar pdfs for ERW and CDS on that site too

I'm guessing that if the rod end doesn't have to be 1/2" for other reasons that size was chosen as it's closest to the tube ID i.e. m14 would leave you bugger all wall thickness and all pitches of m12 are in the 10.something range for tapping which'd work great if 14mm x 2.0mm tube was easy to find but off the top of my head in ERW it's not commonly available with a wall thicker than 1.5mm

 

[Bellow]

The tube I already have is the second on the list here >> Gas List Tube (BS1387) | Hub Le Bas

OD is listed as 16.8 - 17.4mm. Mine is 17.0mm. Calculated ID at 2.35mm WT is 12.3. In reality it is 12.0 >ID > 11.5mm.

Below shows same pipe but in heavy (vs medium) gauge: Gas List Tube (BS1387) | Hub Le Bas

Same OD range and for the limits at WT 2.9mm the IDs calculate at 11.0 and 11.6mm. If the OD is as per my medium (ie 17.0mm) then ID is 11.2mm. The above three IDs are fine for cutting a thread conventionally (even if 11.6 is very slightly over the recommended 11.5 hole size).
I have been told 'heavy' doesn't exist. There may be confusion as the spec has moved from BS1387 to EN10255. Still to do the buckling calculation as final check for suitability before I start pressing the stockist again but otherwise it stacks up as usable (and with conventional cutting taps and drills). Stockist suggests 21.3mm OD Schedule 40 but when I check I think they mean Schedule 160 at 4.9mm WT. Getting a bit chunky and space is at a premium. More research required. Thanks for your help here HR - much appreciated.

edit PS.
To make sense of the links (they are the same) select medium and heavy. My size is 'nominal bore 10mm' and is the second item in each list.

 

[hotrodder]

I briefly thought about pipe yesterday but didn't bother looking up any sizes/schedules as i thought they'd all be all miles out or you'd need a really heavy wall to get the ID somewhere in the ballpark

What you're after looks to exist in real life as well as spec lists... googling bs1387 10mm (UK results only) got some results including Lamberts for BS1387 Red Heavy Screwed and Socketed - 3/8in SCR/SKT 6.5M Self Colour Heavy Tube - Lamberts eShop Website who are showing 12 lengths in stock

 

[Bellow]

Cheers for that HR.
It does exist then. Spoke to my (localish) stockist yesterday and awaiting a call to see what's been found. Hoping they can come up with it as it eases the logistics of delivery. Not only is delivery free, they will deliver the next day - which saves sitting around for several days waiting for a delivery from the other end of the country unable to get anything done for fear of missing it!
Buckling calc next (oh joy!) and if that checks out, back on the phone to stockist.
It looks easy from a distance, this design malarkey. Anything but when you get proper stuck in!

 

[hotrodder]

Yeah, it's PITA when local stockholders carry a limited range. My world is mostly aluminium, stainless and (occasionally) exotics and while there's an Aalco branch 10mins away which takes care of most things aluminium & stainless anything out of the ordinary and i'm screwed unless i move to the midlands or an 'aerospace town' as some flavours of aluminium, stainless and pretty much anything magnesium, titanium or inconel based isn't stocked anywhere else due to lack of demand

Enjoy your maths i've gotta hit the phone and try and find a smallish offcut of magnesium sheet to repair a 'windowed' sump off of something old and Italian