[Tom[_7_]]

I have a propane gas appliance that claims to use 3/8 inch fittings
but I can't seem to measure any occurence of a 9.525mm dimension
(3/8th inch) anywhere in the hardware.

My measurements reveal the following data:

Minor diameter (male): 15.6mm
Major diameter (male): 16.3mm
Therefore, thread depth: 0.35mm
Thread pitch: 1.3333mm (= 19 tpi) Left-hand thread

I've been trawling many popular Google hits on the subject but
without success.

I'm just looking for an adapter for this thread so I can mate it with
a commonly available 15mm copper pipe termination.

Tim

[Roger]

The message
from Tom contains these words:

I have a propane gas appliance that claims to use 3/8 inch fittings
but I can't seem to measure any occurence of a 9.525mm dimension
(3/8th inch) anywhere in the hardware.

My measurements reveal the following data:

Minor diameter (male): 15.6mm
Major diameter (male): 16.3mm
Therefore, thread depth: 0.35mm
Thread pitch: 1.3333mm (= 19 tpi) Left-hand thread

Should be 3/8" BSP but some of your measurements don't quite fit:

Pitch 19 tpi
Major diameter 16.662 mm
Minor diameter 14.950 mm

--
Roger Chapman

[Bob Minchin[_2_]]

Tom wrote:
I have a propane gas appliance that claims to use 3/8 inch fittings
but I can't seem to measure any occurence of a 9.525mm dimension
(3/8th inch) anywhere in the hardware.

My measurements reveal the following data:

Minor diameter (male): 15.6mm
Major diameter (male): 16.3mm
Therefore, thread depth: 0.35mm
Thread pitch: 1.3333mm (= 19 tpi) Left-hand thread

I've been trawling many popular Google hits on the subject but
without success.

I'm just looking for an adapter for this thread so I can mate it with
a commonly available 15mm copper pipe termination.

Tim
There is no part of a 3/8 BSP thread that measures 3/8". Historically it
is the thread that would be cut on thick wall steel pipe with 3/8" bore
Be aware BSP male threads can either be tapered or parallel.
Left hand threads are traditionally used for fuel gases and should have
notches cut in the hexagonal 'corners' to indicate which way to turn them
I would not expect adaptors to be readily available to dissuade
improvised fitting.

Find someone with a lathe who can make you an adaptor up from some brass
to solder onto your 15mm pipe.

Bob

[Dave Baker]

"Tom" wrote in message
...
I have a propane gas appliance that claims to use 3/8 inch fittings
but I can't seem to measure any occurence of a 9.525mm dimension
(3/8th inch) anywhere in the hardware.

My measurements reveal the following data:

Minor diameter (male): 15.6mm
Major diameter (male): 16.3mm
Therefore, thread depth: 0.35mm
Thread pitch: 1.3333mm (= 19 tpi) Left-hand thread

I've been trawling many popular Google hits on the subject but
without success.

http://www.tapshop.net/bsp_etc/

[nightjar]

"Tom" wrote in message
...
I have a propane gas appliance that claims to use 3/8 inch fittings
but I can't seem to measure any occurence of a 9.525mm dimension
(3/8th inch) anywhere in the hardware.

3/8 inch British Standard Pipe Thread is the thread that could be cut on the
outside of a wrought iron pipe with a bore of 3/8 inch. The major diameter
is 0.656 inches and the thread is 19tpi.

Colin Bignell

[RobertL]

On 13 May, 18:09, "nightjar" cpb@insert my surname here.me.uk
wrote:
"Tom" wrote in message

...

I have a propane gas appliance that claims to use 3/8 inch fittings
but I can't seem to measure any occurence of a 9.525mm dimension
(3/8th inch) anywhere in the hardware.

3/8 inch British Standard Pipe Thread is the thread that could be cut on the
outside of a wrought iron pipe with a bore of 3/8 inch. The major diameter
is 0.656 inches and the thread is 19tpi.

Colin Bignell


AIUI, in the original standard the 3/8" was the internal diameter of
the pipe (the bore) but sometime after the original standard was
defined they increased the standard bore so nothing on a 3/8" pipe
measures 3/8" any more.

Robert

[nightjar]

"RobertL" wrote in message
...
On 13 May, 18:09, "nightjar" cpb@insert my surname here.me.uk
wrote:
"Tom" wrote in message

...

I have a propane gas appliance that claims to use 3/8 inch fittings
but I can't seem to measure any occurence of a 9.525mm dimension
(3/8th inch) anywhere in the hardware.

3/8 inch British Standard Pipe Thread is the thread that could be cut on
the
outside of a wrought iron pipe with a bore of 3/8 inch. The major
diameter
is 0.656 inches and the thread is 19tpi.

Colin Bignell


AIUI, in the original standard the 3/8" was the internal diameter of
the pipe (the bore) but sometime after the original standard was
defined they increased the standard bore so nothing on a 3/8" pipe
measures 3/8" any more.

What happened was that wrought iron (up to 2.5 inches) and cast iron (3
inches and above) were replaced with steel, which could have a thinner wall
for the same bursting strength. As the OD had to remain the same, the bore
changed. Today, Class E uPVC pipe is about the same wall thickness as the
original materials, at least in larger sizes - I don't usually deal with
anything smaller than 1 inch bore.

Colin Bignell

[RobertL]

On May 13, 9:18*pm, "nightjar" cpb@insert my surname here.me.uk
wrote:
"RobertL" wrote in message

...





On 13 May, 18:09, "nightjar" cpb@insert my surname here.me.uk
wrote:
"Tom" wrote in message

. ..

I have a propane gas appliance that claims to use 3/8 inch fittings
but I can't seem to measure any occurence of a 9.525mm dimension
(3/8th inch) anywhere in the hardware.

3/8 inch British Standard Pipe Thread is the thread that could be cut on
the
outside of a wrought iron pipe with a bore of 3/8 inch. The major
diameter
is 0.656 inches and the thread is 19tpi.

Colin Bignell

AIUI, in the original standard the 3/8" was the internal diameter of
the pipe (the bore) but sometime after the original standard was
defined they increased the standard bore so nothing on a 3/8" pipe
measures 3/8" any more.

What happened was that wrought iron (up to 2.5 inches) and cast iron (3
inches and above) were replaced with steel, which could have a thinner wall
for the same bursting strength. As the OD had to remain the same, the bore
changed.


out of interest, does anyone know when this change took place?

Robert

[Tom[_7_]]

On Wed, 13 May 2009 18:04:32 +0100, Bob Minchin
wrote:

There is no part of a 3/8 BSP thread that measures 3/8". Historically it
is the thread that would be cut on thick wall steel pipe with 3/8" bore

....

Be aware BSP male threads can either be tapered or parallel.
Left hand threads are traditionally used for fuel gases and should have
notches cut in the hexagonal 'corners' to indicate which way to turn them
I would not expect adaptors to be readily available to dissuade
improvised fitting.

Find someone with a lathe who can make you an adaptor up from some brass
to solder onto your 15mm pipe.

Bob


Thanks Bob, and others, all is much clearer now. I wondered about the
small notches on the facets of the fastening nut but they are exactly
as you state, indicating the left-hand thread. The threads in my case
are parallel and the seal facilitated by a conical end section mating
with a convex part withing the female connector.

A one-piece stock/bespoke adapter would work but I think will opt to
do it with a short and suitably terminated length of hose - One end
3/8 BSP (left-handed) hose connector (when I can find one) with the
other end using a domestic water plumbing thread.

If I do stumble upon a one-piece brass adapter with left/right-hand
thread combination then I am still interested in that as a solution.
It wil be intriguing to to tighten anyway!

I tend to use BES for these items, does anyone have any other online
stockist suggestions that might offer the pipe or one-piece adapter?

[nightjar]

"RobertL" wrote in message
...
....
What happened was that wrought iron (up to 2.5 inches) and cast iron (3
inches and above) were replaced with steel, which could have a thinner
wall
for the same bursting strength. As the OD had to remain the same, the
bore
changed.

out of interest, does anyone know when this change took place?

I would expect that it largely happened during the second half of the 19th
century, once the Bessemer process allowed steel to be produced cheaply.

Colin Bignell