Pipe sizes were defined in the 'old days' when everything was threaded
connections and you needed to be able to flow a certain amount of gas or
liquid.

Pipe has a defined OD so all the different pipe fittings can be be
attached. The ID is sized so that "normal" wall thickness (designated
'Schedule 40')will give an ID that is equal to or larger than the
nominal dimension. After that, there are Schedule 5, 10, 20, 40, 80, and
160 to handle different pressures which give you all the different wall
thicknesses. Confused yet?

Michael Koblic wrote:
I was looking up dimensions of steel pipe. I found a few tables with
figures. Here is what puzzles me:
Take a 3/4 pipe: ID=20 mm. OD=26.7 mm. This is the same for about five
different pipes listed. Yet each pipe *had different wall thickness*. How is
this possible? Another Tardis principle?

"RoyJ" wrote in message
m...
Pipe sizes were defined in the 'old days' when everything was threaded
connections and you needed to be able to flow a certain amount of gas or
liquid.

Pipe has a defined OD so all the different pipe fittings can be be
attached. The ID is sized so that "normal" wall thickness (designated
'Schedule 40')will give an ID that is equal to or larger than the nominal
dimension. After that, there are Schedule 5, 10, 20, 40, 80, and 160 to
handle different pressures which give you all the different wall
thicknesses. Confused yet?

Michael Koblic wrote:
I was looking up dimensions of steel pipe. I found a few tables with
figures. Here is what puzzles me:
Take a 3/4 pipe: ID=20 mm. OD=26.7 mm. This is the same for about five
different pipes listed. Yet each pipe *had different wall thickness*. How
is this possible? Another Tardis principle?

I think the ID of Schedule 80 pipe is closest to the Nominal Size. At least
it is for 3/4" as I recently made a bunch of spacers for 3/4" bolts from
3/4" Schedule 80 pipe after checking the size tables.

I recently acquired a large manual of Society of Automotive Engineers (SAE)
standards for 1957 and I noticed it has lengthy standards for many things,
such as for windshield wiper hose in two sizes. It includes requirements and
testing for such things as pressure, vacuum, and radius of bend!!!

Don Young

"RoyJ" wrote in message
m...
Pipe sizes were defined in the 'old days' when everything was threaded
connections and you needed to be able to flow a certain amount of gas or
liquid.

Pipe has a defined OD so all the different pipe fittings can be be
attached. The ID is sized so that "normal" wall thickness (designated
'Schedule 40')will give an ID that is equal to or larger than the nominal
dimension. After that, there are Schedule 5, 10, 20, 40, 80, and 160 to
handle different pressures which give you all the different wall
thicknesses. Confused yet?


OK, if I understand you right the nominal size refers to the ID but it is
the *OD* that is held constant and the ID varies with the schedule and the
wall thickness. Why, that makes perfect sense!

Not surprising I feel like Alice in wonderland...

OK, if I understand you right the nominal size refers to the ID but it is
the *OD* that is held constant and the ID varies with the schedule and the
wall thickness. Why, that makes perfect sense!

Not surprising I feel like Alice in wonderland...


Correct on both counts!!!!

"Michael Koblic" wrote in message
...

"RoyJ" wrote in message
m...
Pipe sizes were defined in the 'old days' when everything was threaded
connections and you needed to be able to flow a certain amount of gas or
liquid.

Pipe has a defined OD so all the different pipe fittings can be be
attached. The ID is sized so that "normal" wall thickness (designated
'Schedule 40')will give an ID that is equal to or larger than the nominal
dimension. After that, there are Schedule 5, 10, 20, 40, 80, and 160 to
handle different pressures which give you all the different wall
thicknesses. Confused yet?


OK, if I understand you right the nominal size refers to the ID but it is
the *OD* that is held constant and the ID varies with the schedule and the
wall thickness. Why, that makes perfect sense!

Not surprising I feel like Alice in wonderland...

You got it!!

Don Young

On Oct 26, 2:15*am, "Michael Koblic" wrote:
"RoyJ" wrote in message

m...

Pipe sizes were defined in the 'old days' when everything was threaded
connections and you needed to be able to flow a certain amount of gas or
liquid.

Pipe has a defined OD so all the different pipe fittings can be be
attached. The ID is sized so that "normal" wall thickness (designated
'Schedule 40')will give an ID that is equal to or larger than the nominal
dimension. After that, there are Schedule 5, 10, 20, 40, 80, and 160 to
handle different pressures which give you all the different wall
thicknesses. Confused yet?

OK, if I understand you right the nominal size refers to the ID but it is
the *OD* that is held constant and the ID varies with the schedule and the
wall thickness. Why, that makes perfect sense!

Because the threads are on the OD.

Steel pipe isn't precise in size and definitely isn't guaranteed to be
round, as you'll find out when you try turning it in a lathe. Brass
pipe is much closer. The pipe I've bought recently from HD and Lowes
does machine and weld nicely.

"Jim Wilkins" wrote in message
...

Steel pipe isn't precise in size and definitely isn't guaranteed to be
round, as you'll find out when you try turning it in a lathe. Brass
pipe is much closer. The pipe I've bought recently from HD and Lowes
does machine and weld nicely.

***Yes. My RedNeck lathe v3.0 has not done a good job so far I am sad to say
:-) BTW do not ask - one day I might muster sufficient courage to tell.
I have got a pair of superb little 1" pillow blocks cheap. I found a 9"
pulley to match from scrap - cleaned up nicely. However, taking 1mm off the
pipe diameter - priceless.

Still, I have solved minor intellectual puzzles (which I am sure you guys
would have done on a sub-tentorial basis), such as finding a centre on a
mounted endcap (sadly, the bolt through the centre will not turn the pipe in
a true concentric fashion even with a liberal use of hammer). On the other
end of the pipe I fashioned a decent red neck 4-jaw chuck with four 10-32
screws. Much better result.

I was thinking of a floor flange in lieu of a face plate, however the way
they fit together with the pipe I would have to take a whopping 3 mm off the
flange thickness to make it run true.

I might cut a 1"-8 thread in one end of the pipe instead - that would have
all sorts of other benefits.

BTW the local machine shop quoted me $45 for the job...

--
Michael Koblic,
Campbell River, BC

On Mon, 27 Oct 2008 19:33:21 -0700, the infamous "Michael Koblic"
scrawled the following:


"Jim Wilkins" wrote in message
...

Steel pipe isn't precise in size and definitely isn't guaranteed to be
round, as you'll find out when you try turning it in a lathe. Brass
pipe is much closer. The pipe I've bought recently from HD and Lowes
does machine and weld nicely.

***Yes. My RedNeck lathe v3.0 has not done a good job so far I am sad to say
:-) BTW do not ask - one day I might muster sufficient courage to tell.

So, Mikey, who holds your beer while you're using it?

--
Some days, it's not even worth chewing through the restraints.

On Oct 27, 5:07*pm, Jim Wilkins wrote:
On Oct 26, 2:15*am, "Michael Koblic" wrote:





"RoyJ" wrote in message

om...

Pipe sizes were defined in the 'old days' when everything was threaded
connections and you needed to be able to flow a certain amount of gas or
liquid.

Pipe has a defined OD so all the different pipe fittings can be be
attached. The ID is sized so that "normal" wall thickness (designated
'Schedule 40')will give an ID that is equal to or larger than the nominal
dimension. After that, there are Schedule 5, 10, 20, 40, 80, and 160 to
handle different pressures which give you all the different wall
thicknesses. Confused yet?

OK, if I understand you right the nominal size refers to the ID but it is
the *OD* that is held constant and the ID varies with the schedule and the
wall thickness. Why, that makes perfect sense!

Because the threads are on the OD.

Steel pipe isn't precise in size and definitely isn't guaranteed to be
round, as you'll find out when you try turning it in a lathe. Brass
pipe is much closer. The pipe I've bought recently from HD and Lowes
does machine and weld nicely.- Hide quoted text -

- Show quoted text -

Yup, been there. I wanted to make an extended support column for my
cheapie bench drill press, found a suitable piece of pipe in the drop
bin at the local hardware store. Just a bit oversize, no lathe big
enough and no pipe center anyway. I used a belt grinder to do the
deed. Found out the stuff was square when I started grinding it
down. So, round and round for several hours on a piece that was maybe
3" in diameter and 3' long. Used the table support for gauging and a
Magnum-sized magic marker for finding high spots. Got it within .005"
from end to end, close enough for the table support to lock tightly
from top to bottom. Needed the extended column for fitting a tubing
fish-mouthing jig. Works great and I'm pretty sure I wouldn't have
gotten as good a finish on a lathe, had I had one handy. Belt grinder
has proven indispensable for a lot of things since then, that was the
first real project I used it on.

Stan

wrote in message
...
Yup, been there. I wanted to make an extended support column for my
cheapie bench drill press, found a suitable piece of pipe in the drop
bin at the local hardware store. Just a bit oversize, no lathe big
enough and no pipe center anyway. I used a belt grinder to do the
deed. Found out the stuff was square when I started grinding it
down. So, round and round for several hours on a piece that was maybe
3" in diameter and 3' long. Used the table support for gauging and a
Magnum-sized magic marker for finding high spots. Got it within .005"
from end to end, close enough for the table support to lock tightly
from top to bottom. Needed the extended column for fitting a tubing
fish-mouthing jig. Works great and I'm pretty sure I wouldn't have
gotten as good a finish on a lathe, had I had one handy. Belt grinder
has proven indispensable for a lot of things since then, that was the
first real project I used it on.

***LOL! Belt sander is my best friend. I tried spinning the pipe on a sort
of mandrel. Hours of fun! Not enough patience. P.ss-poor result. But I am
working on an alternative...

--
Michael Koblic,
Campbell River, BC

"Larry Jaques" wrote in message
...

***Yes. My RedNeck lathe v3.0 has not done a good job so far I am sad to
say
:-) BTW do not ask - one day I might muster sufficient courage to tell.

So, Mikey, who holds your beer while you're using it?


That's what the hard-hat with two duct-taped cans and a hose is for!

On Oct 25, 7:35*pm, RoyJ wrote:
Pipe sizes were defined in the 'old days' when everything was threaded
connections and you needed to be able to flow a certain amount of gas or
liquid.

Pipe has a defined OD so all the different pipe fittings can be be
attached. The ID is sized so that "normal" wall thickness (designated
'Schedule 40')will give an ID that is equal to or larger than the
nominal dimension. After that, there are Schedule 5, 10, 20, 40, 80, and
160 to handle different pressures which give you all the different wall
thicknesses. Confused yet?

My understanding is that pipe had an ID that was the nominal dimension
and the OD was such that the strength was good for normal water
pressures. When the steel used for pipe improved, the OD stayed the
same so threaded fittings still worked. But with the improved steel
the ID could and was made bigger. So now steel pipe has an ID that is
somewhat bigger than the nominal size.


Dan

On Tue, 28 Oct 2008 18:07:54 -0700, the infamous "Michael Koblic"
scrawled the following:


"Larry Jaques" wrote in message
.. .

***Yes. My RedNeck lathe v3.0 has not done a good job so far I am sad to
say
:-) BTW do not ask - one day I might muster sufficient courage to tell.

So, Mikey, who holds your beer while you're using it?


That's what the hard-hat with two duct-taped cans and a hose is for!

OK, got it. So where's the video?

--
Change is the process by which the future invades our lives.
-- Alvin Toffler

"Larry Jaques" wrote in message
...
On Tue, 28 Oct 2008 18:07:54 -0700, the infamous "Michael Koblic"
scrawled the following:


"Larry Jaques" wrote in message
. ..

***Yes. My RedNeck lathe v3.0 has not done a good job so far I am sad to
say
:-) BTW do not ask - one day I might muster sufficient courage to tell.

So, Mikey, who holds your beer while you're using it?


That's what the hard-hat with two duct-taped cans and a hose is for!

OK, got it. So where's the video?


Repo man got the camcorder...