Today's excitement was a trip to "Global House" I ask for some  32mm to 25mm adapters for ldpe pipe they sell..........anyway they hadnt got any but as i walked over to their "pipe display" I noticed all the pipe sizes were wrong for the ldpe pipe, these had been typed  up and stuck on with sellotape on each diameter pipe

25mm = 3/4  inch

32 mm = 1inch

40 mm = 1-1/4 inch

 

etc etc all the way  up to 100mm +

 

I asked my Wife to explain to them but they insist its correct and "weve sold it for 10 years"

So be warned when buying ldpe or hdpe pipe from Global that if you ask for 1  inch pipe your'e  going to get  32mm etc etc apparently Thai pipe is " different" even with a rule I showed them 1 inch was 25mm.......nope not having any of it.

Next time im in there Ill take a photo of it, its  clear someone who has typed up the signs and stuck them on all the different sized pipes has ferked up

Looked at a couple of Thai sites and they all list it the same way 32 mm is 1  inch although a Uk site shows it as 3  different sizes due to wall thickness

If only I could find it...

I had investigated the topic after finding that a so called "1/2 inch" PVC pipe has absolutely no size of 0.5 inch (1.25 cm).

Try on your own!

Interior as well as exterior much bigger than 0.5 inch.

Exterior diameter about 2.2 cm (0.86 inch).

I learned that this applies to all sizes smaller than 4(?) inch .

From 4 inch upward the exterior diameter is identical to the "label" (maybe "metricized" with 1 inch = 2.5 cm instead of 2.54 cm.

All sizes below that limit are "trade names" for "historic reasons" only.

 

Interior diameters can vary on wall thickness of course.
 

 

Edited September 19, 20169 yr by KhunBENQ

2 hours ago, kannot said:

Looked at a couple of Thai sites and they all list it the same way 32 mm is 1  inch although a Uk site shows it as 3  different sizes due to wall thickness

 

I just have a piece of PVC pipe at hand.

Labeled as 25 mm (1 "). "mm" in Thai script.

Diameter 34 mm, inside about 30 mm.

Absolutely "normal".

Edited September 19, 20169 yr by KhunBENQ

Found it, here is the table with the real sizes of PVC water pipes:

 

http://www.thaipipe.com/products&services/upvcpipe.htm

 

You can see the 25 (1") with 34 mm outside diameter.

But memory seemed to serve me wrong about the bigger diameters.

All "nominal size" are different from the real size.

Edited September 19, 20169 yr by KhunBENQ

"Nominal" size is the operative word which often means loosely related, a trade name, etc.

 

http://www.engineeringtoolbox.com/nps-nominal-pipe-sizes-d_45.html

Quote

 

Pipes are made of a wide variety of materials - like galvanized steel, black steel, copper, cast iron, concrete, and various plastics such as ABS, PVC, CPVC, polyethylene, polybutylene and more.

Pipes are identified by "nominal" or "trade" names that are loosely related to the actual dimensions. For instance, a 2-inch galvanized steel pipe has an inside diameter of about 2 1/8 inches and an outside diameter of about 2 5/8 inches.

In plumbing pipe size is referred to as nominal pipe size - NPS, or "Nominal Pipe Size". The metric equivalent is called DN or "diametre nominel". The metric designations conform to International Standards Organization (ISO) usage and apply to all plumbing, natural gas, heating oil, and miscellaneous piping used in buildings. The use of NPS does not conform to American Standard pipe designations where the term NPS means "National Pipe Thread Straight".

 

 

 

9 hours ago, KhunBENQ said:

 

I just have a piece of PVC pipe at hand.

Labeled as 25 mm (1 "). "mm" in Thai script.

Diameter 34 mm, inside about 30 mm.

Absolutely "normal".

I got similar with inside diameter of 1inch being 28mm...............it actually  helped me at the time as i was calculating friction loss and the slightly  bigger internal diameter made it better!!!

8 hours ago, Pib said:

"Nominal" size is the operative word which often means loosely related, a trade name, etc.

 

http://www.engineeringtoolbox.com/nps-nominal-pipe-sizes-d_45.html

 

 

except  when it comes to hdpe  pipe then 25mm is 3/4 inch and all the others are the same ie 32mm is 1 inch etc etc bizarre. Theres  nominal then "nominal Thai"

So if  you are joining up to something and ask for 1  inch your gonna  be in for a shock when the reel arrives

Edited September 20, 20169 yr by kannot