Question About Iron Pipe Dimension

[downslope]

Should the inside dimension of a half-inch black iron pipe be the same as a half-inch galvanized pipe? The reason I ask is I'm building something for a gate where I need a 5/8" pin to fit inside the pipe. I was fiddling around with the pipe at the big-box store and it seemed the pin would fit snug in the black pipe but was no go in the galvanized, but I couldn't tell if the galvanized had a burr in it.

 

[Inkomodius]

Iron pipe and tubing use different measurements. As well as it depends on what wall thickness you were looking at between the two.

So most likely no, you could try a steel supplier to find a solution or a machine shop usually has a reference book showing the ID's of various tube and pipe products that will fit your needs.

 

[Gary Fowler]

Steel pipe ID is the same for black and galvanized, however, the galvanized coating takes us a few thousandth in both ID and OD. They dont make different pipe sizes just for galvanizing. Just like painting, the coating adds to the thickness of the pipe. THis will be true for any size pipe, black is going to have a larger ID than galvanized. If I wanted to use it for pinning, I would just drill out the internal galvanizing to accept the pin and put a generous amount of grease on the pin to prevent it from rusting on the inside.

 

[Gary Fowler]

NPS pipe sizes are standardized using the inside dimensions for all sizes up to and including 12" diameter. At that point the switch to the OD so a 14" pipe is 14" in outside diameter. For the pipe that you were looking at, it must have been 3/8" NPS standard wall with an outside diameter of .675" The OD would stay the same regardless of pipe wall thickness but the internal diameter would get smaller as the pipe schedule gets higher. 3/8" pipe only comes in schedule 40 and schedule 80 with .091 wall and .126 wall respectively, any thicker and it wouldnt have a hole in it. You can find this info for all pipes by searching the net with "pipe dimensions" as your search.

 

[SPYDERLK]

Should the inside dimension of a half-inch black iron pipe be the same as a half-inch galvanized pipe? The reason I ask is I'm building something for a gate where I need a 3/8" pin to fit inside the pipe. I was fiddling around with the pipe at the big-box store and it seemed the pin would fit snug in the black pipe but was no go in the galvanized, but I couldn't tell if the galvanized had a burr in it.

As said, same pipe but with a galvanize coating that tightens the inner D slightly. Just measured -- 1/2 pipe ID ~ 0.630", 3/8 pipe ID ~ 0.470". These measurements are taken inward of the short rolled in/burr area normally left at the very end from cutting and threading the pipe.
larry

 

[BHD]

actually pipe is standard on the out side of the pipe,
even tho the internal general or average is what it is called by,
and the internal diameter can be different depending on the wall thickness or pipe type,

the concern is to be able to thread the pipe and have it all work on the same threads,

as said galvanized most likely will be smaller ID as the coating will increase the pipe thickness,

but the schedule of the pipe will change the ID, and at times the material used in the pipe may the wall thickness as well,

schedule 40 is usually the normal pipe that is sold was water pipe,

this chart show the ID as well as the wall thickness for pipes,
USA Industries

 

[SPYDERLK]

actually pipe is standard on the out side of the pipe,
even tho the internal general or average is what it is called by,
and the internal diameter can be different depending on the wall thickness or pipe type,

the concern is to be able to thread the pipe and have it all work on the same threads,

as said galvanized most likely will be smaller ID as the coating will increase the pipe thickness,

but the schedule of the pipe will change the ID, and at times the material used in the pipe may the wall thickness as well,

schedule 40 is usually the normal pipe that is sold was water pipe,

this chart show the ID as well as the wall thickness for pipes,
USA Industries

Beware of the many errors in wall thickness listed in chart.
larry

 

[downslope]

Sorry, I made a mistake in the initial post.
The pin is 5/8" (.625) not 3/8". So the 1/2" pipe (.630" ID) should be perfect.
If I use the galvanized I'll just drill/ream it a little and grease it up.

I did some reading and there is nothing on 1/2" pipe that actually measures 1/2". It all relates back to early days of pipe and having to keep the same OD as manufacturing methods improved so that things of the same size could thread together.

Pipe (material) - Wikipedia, the free encyclopedia

 

[nybirdman]

Boy ,all this pipefitter talk makes me want to unretire!!!
ya right.................25years UA Locals 117&73

 

[pat32rf]

Does the pin HAVE to be 5/8? Maybe you could use a long 9/16" or 3/4" bolt/shaft to get a closer fit.

 

[dcyrilc]

If you're just needing a short piece for using with a pin, why not use DOM tubing and just buy the length you need?

 

[OldMcDonald]

All very interesting, and confusing for those not familiar with what a couple of posters have already said - the measurements (Imperial and originally for Englsih use only) relate to the OD of the pipe for threading purposes. Try living in a metric country (I am in Portugal) everything except metal pipe is meaured in millimetres, but metal pipe is in inches. Very amusing to hear non-English speaking people talking about "eenches" unless you are the poor character trying to match up their metric measurements with your Imperial ones. But, they are such nice people so something is always worked out.

 

[rjmack]

Boy ,all this pipefitter talk makes me want to unretire!!!
ya right.................25years UA Locals 117&73

hey bro', 488 :thumbsup:

 

[Raspy]

The problem is using the word "pipe". Since that word usually means a measurement close, but not exactly, the inside diameter (depending on what schedule it is) but refers to a standardized material that is the same on the outside, but no where near the listed size (1/2 inch pipe is about 7/8"OD, 1"pipe is about 1 3/8" OD, etc). Instead, use the word "tubing". Now you are referring to the outside diameter. So, 7/8" copper tubing is 7/8" OD and it's the same exact thing as 3/4' copper pipe. Then you have to mention it's wall thickness by using letters such as "M" or "L" and then call out if it's hard or soft. Now go to the metal yard and get some steel tubing and call out its OD by refering to its size and then call out it's wall thickness in thousandths. Sheesh :laughing: :laughing:

For structural stuff where hinges and pins and fabricating frames and such is concerned, use steel tubing if you can. The ID of water pipe is very rough and has a welded seam that makes its ID non exact. Plus, you can get square tubing. :laughing: Try threading that!