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Table 4.14
Nominal Thread L, l , D 1, D 2, B, b 1, b 2, h, Number Chamfer
bore, Dy, G, inch mm mm mm mm mm mm mm mm of ribs с, mm
mm
10 3/8 30 8 22 20 2 2 3.5 2 2 1
15 1/2 36 9 26 24 2 2 4 2 2 1,5
20 3/4 39 10.5 32.5 30 2.5 2 4 2.5 2 1,5
25 1 45 11 39.5 37 2.5 2.5 4.5 2.5 4 2
32 1 50 13 49 46 3 2.5 5 3 4 2
40 1 55 15 56 53 3 3 5 3 4 2
50 2 65 17 68.5 65 3.5 3 5 3.5 6 2
Note. Sizes of external and internal diameters are resulted in table 4.12.
The example of the conventional denotation of a pipe coupling with the nominal bore 20 mm:
Pipe Coupling 20 State Standard 8955-75.

4.5.5.4 REDUCERS OR REDUCING COUPLINGS (STATE STANDARD 8957-75)

Figure 4.29 – Conventional drawings of reducing coupling

Table 4.15
Nominal Threads L, l , l 1, l 2, D 1, D 2, D 3, D 4, b, b 1, b 2, h,
bore, Dy, G 1хG 2, mm mm mm mm mm mm mm mm mm mm mm mm ribs
mm inch Number of

20х10 3/4 х3/8 39 10 13 10 32 30 20 22 2 2 3.5 2 2
20х15 3/4х1/2 39 10 13 10 32 30 24 26 2 2 3.5 2 2
25х15 1 х 1/2 45 11 15 12 39 37 24 26 2 2 4 2 4
32х15 1 х1/2 50 13 17 12 48.5 46 24 26 2.5 2 4 2.5 4
32х20 1 х3/4 50 13 17 12 48.5 46 30 32.5 2.5 2 4 2.5 4
32х25 1 х 1 50 13 17 12 48.5 46 37 39.5 2.5 2 4 2.5 4
40х20 1 х3/4 55 15 19 13 55.5 53 30 32.5 2.5 2.5 4.5 2.5 4
40х25 1 х 1 55 15 19 13 55.5 53 37 39.5 2.5 2.5 4.5 2.5 4
50х25 2х1 65 17 21 15 68 65 37 40 3 2.5 5 3 6

The example of the conventional denotation of a reducing coupling with the nominal bore 20
mm: Reducing Coupling 20 State Standard 8957-75.

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