Thread + Tube Info

Thread + Tube Info

Info about pool hoses and threads

Plastic tubes and hoses have different dimensions depending on the region.

In Europe the metric system is usually installed.

In Great Britain, America and partly in the Far East (China), this is usually the inch system.

Here I show the differences.  Go direct to the hose and pipe info


There are also differences in the screw connections and threads.



Overview of common pipes in the Pool + Spa area

Metric system:

Plastic tubes Outer diameter:

20 mm

32 mm

40 mm

50 mm

63 mm

75 mm

Hose for pool and spa (metric):


American / British system:

Why is a 1 inch pipe 33 mm?

At the beginning of the 20th century, the pipe size was related to the inside diameter. Since the inside diameter is an important value for the pipe, the inside width of a 1-inch pipe is 25.4 mm. Due to the steel quality at that time, the outer diameter was approx. 33 mm. Accessories and tools were also made. The steel quality was improved and the pipe wall could be made thinner. Since the accessories and threading tools were manufactured according to the outer diameter, the result was a larger inner diameter. If a pipe with an outside diameter of approximately 33mm is installed, it is still "1" pipe.

Plastic tubes Outer diameter:

3/8 "- 17.2 mm

1/2 "- 21.3 mm

3/4 "- 26.9 mm

1 "- 33.7 mm

1 1/2 "(1.5") - 48.3 mm

2 "- 60.3 mm

2 1/2 "- 72.5 mm

Hose for Pool and Spa (British / American):