double_nipple

BSP - NPT standards

BSP NPT

NPT = American National Pipe Tapered 60 degree thread

BSP could be either:
BSPP = British Standard Pipe Parallel
BSPT = British Standard Pipe Tapered 55 degree thread

With the 1/2" and 3/4" in both of these they are difficult to tell the difference as both of these have 14 threads per inch. The other sizes the threads per inch is different.

The site below show the slight differences, More information in the following document:

 

Pipes threads data table
dimension's data of irrigation systems pipes threads. BSPT and NPT piping threads  standards

Nominal
Diameter

BSPT pipe threads

NPT pipe threads

Diameter

number of loop
in 1 inch length

Diameter

number of loop
in 1 inch length

The Pipe
(mm)

Outer
(mm)

Internal bore
hole for thread

The Pipe
(mm)

Internal bore
hole for thread

    1/8"

10.00

9.73

8.6

28

10.29

8.49

27

    1/4"

13.25

13.16

11.4

19

13.72

11.00

18

    3/8"

16.75

16.66

14.9

19

17.15

14.42

18

    1/2"

21.25

20.95

18.6

14

21.34

17.81

14

    5/8"

22.42

22.12

20.6

14

    3/4"

26.75

26.44

24.1

14

26.67

23.13

14

  1"

33.50

33.25

30.3

11

33.40

29.06

11.5

  1  1/4"

42.25

41.91

38.9

11

11.5

  1  1/2"

48.25

47.80

44.8

11

11.5

  2"

60.00

59.61

56.6

11

11.5

  2  1/2"

75.50

75.18

72.2

11

 

 

8

  3"

88.90

87.88

84.6

11

 

 

8

  4"

114.30

113.03

110.1

11

 

 

8

This information is a courtesy of irrigationglobal.com drip irrigation systems and equipment

 Most countries uses BSP threads for irrigation systems assembly.

Known (to us) countries who uses NPT threads for irrigation systems:
USA, Mexico, Venezuela, Japan. Peru, Puerto Rico, Hawaii

Read about BSP in wikipedia
Read about NPT in wikipedia
http://www.colder.com/Portals/0/pdfs/NPT.pdf

Utility links:

irrigation filters mesh and micron conversion

irrigation pe piping metric standarts

irrigation pe piping head losses

inches to metric conversion table