Stainless steel reducing nipple, male/male 316, BSP threaded
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|---|---|---|---|---|
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Stainless steel reducing nipple, male/male 316, BSP threaded
Stainless steel reducing nipple, male/male 316, threaded BSP (R taper to ISO 7-1) at both ends. It joins two Rp tapped ports of different sizes, in 26 size pairs from 1/4" × 1/8" to 3" × 2"1/2 (DN8 × DN6 to DN80 × DN65). PN 20 up to 40 °C, drinking water compliant, for all fluids compatible with stainless steel.
Description of the stainless steel BSP reducing nipple
In plumbing, this threaded stainless steel pipe fitting sits between two female components of different sizes, with no welding or soldering. Investment cast (lost wax) in CF8M (AISI 316) stainless steel, it is designed, manufactured and inspected to the ISO 4144 standard.
The size pair is read large end first: a 1/2" × 3/8" (French size 15x21 × 12x17, i.e. DN15 × DN10) screws into a 1/2" Rp tapped port at one end and a 3/8" one at the other. The R threads, which are taper, fit into a parallel Rp tapped thread and are not compatible with NPT. In the middle, six flats take the spanner.
Stainless steel reducing nipple: technical specifications
| Material | CF8M (AISI 316) stainless steel |
| Manufacture | Investment casting (lost wax) |
| Standard | Designed, manufactured and inspected to ISO 4144 |
| Thread | R1 and R2 male (taper) to ISO 7-1 (BSP, R series). Mate with an Rp tapped thread (parallel). Not compatible with NPT |
| Connection | Male/male |
| Nominal pressure | PN 20: 20 bar from −20 to 40 °C, lower above that |
| Temperature | −20/+220 °C, permissible pressure reduced above 40 °C |
| Fluids | All fluids compatible with stainless steel |
| Sizes | 26 size pairs, from 1/4" × 1/8" to 3" × 2"1/2 |
| Compliance | 4MS; drinking water: French order of 25 June 2020 |
Pressure and temperature
PN 20 applies from −20 to 40 °C. Above that, the permissible pressure falls. Values marked ≈ are read from the pressure/temperature curve in the technical data sheet.
| Temperature (°C) | Max. pressure (bar) |
|---|---|
| −20 → 40 | 20 |
| 100 | ≈ 16.5 |
| 150 | ≈ 15 |
| 220 | ≈ 13.5 |
Certification and compliance
According to the technical data sheet for the series:
- 4MS: compliant with the 4MS requirements, the harmonized European rules for materials and products in contact with drinking water.
- Drinking water: compliant with the French order (arrêté) of 25 June 2020 on metallic materials and products in contact with water intended for human consumption.
Uses and installation advice
This reducing nipple is used on drinking water systems and on circuits carrying fluids compatible with 316 stainless steel. For two tapped ports of the same size, choose a stainless steel male/male nipple; between two male threads, a stainless steel female/female reducing coupling. Check fluid compatibility and the permissible pressure at the working temperature.
- Thread sealing: an Rp/R joint seals on the threads, using PTFE or jointing compound suited to the fluid and the working temperature.
- Galling: with stainless steel on stainless steel, the thread can gall. Screw in gradually, without forcing.
- Tightening: tighten with an open-ended or adjustable spanner on the central flats, not with pipe grips or pliers, which mark stainless steel.
- Dissimilar metals: on a water system, stainless steel forms a galvanic couple with galvanized steel or cast iron. On the brass side, with few exceptions, our flat-seal and conical-seat fittings are threaded to ISO 228-1 (BSPP, parallel), not Rp.
Technical drawing
Dimensions (mm)
Dimensions in millimetres, PN in bar, weight in kilograms. R1 and R2: large and small threads. ØA and ØB: bores of the large and small ends. C: dimension across flats. L1 and L2: thread lengths at the large and small ends. L3: overall length.
| R1 × R2 size | French size | ØA | ØB | C | L1 | L2 | L3 | PN (bar) | Weight (kg) |
|---|---|---|---|---|---|---|---|---|---|
| 1/4" × 1/8" | 8x13 × 5x10 | 8.5 | 6 | 14.5 | 13.5 | 11 | 30 | 20 | 0.017 |
| 3/8" × 1/8" | 12x17 × 5x10 | 11 | 5.5 | 18.5 | 15.5 | 15.5 | 38.5 | 20 | 0.030 |
| 3/8" × 1/4" | 12x17 × 8x13 | 11 | 8 | 19 | 14.5 | 12.5 | 34.5 | 20 | 0.031 |
| 1/2" × 1/8" | 15x21 × 5x10 | 14.5 | 5.5 | 22 | 17 | 11 | 36 | 20 | 0.040 |
| 1/2" × 1/4" | 15x21 × 8x13 | 14.5 | 8 | 23 | 17 | 14 | 38 | 20 | 0.046 |
| 1/2" × 3/8" | 15x21 × 12x17 | 14.5 | 11 | 23 | 17 | 14.5 | 40 | 20 | 0.050 |
| 3/4" × 1/4" | 20x27 × 8x13 | 20 | 8.5 | 29 | 18 | 13 | 40 | 20 | 0.069 |
| 3/4" × 3/8" | 20x27 × 12x17 | 20.5 | 11 | 29 | 18 | 15 | 41.5 | 20 | 0.071 |
| 3/4" × 1/2" | 20x27 × 15x21 | 20 | 14.5 | 28.5 | 17 | 17 | 42.5 | 20 | 0.069 |
| 1" × 1/4" | 26x34 × 8x13 | 26.5 | 8.5 | 35 | 18 | 12.5 | 40.5 | 20 | 0.086 |
| 1" × 3/8" | 26x34 × 12x17 | 26.5 | 11 | 36 | 18.5 | 15 | 44.5 | 20 | 0.106 |
| 1" × 1/2" | 26x34 × 15x21 | 26 | 14.5 | 35.5 | 19 | 17 | 47 | 20 | 0.108 |
| 1" × 3/4" | 26x34 × 20x27 | 26 | 20 | 35.5 | 18.5 | 18 | 48 | 20 | 0.111 |
| 1"1/4 × 1/2" | 33x42 × 15x21 | 34.5 | 14.5 | 44.5 | 21 | 17 | 50 | 20 | 0.165 |
| 1"1/4 × 3/4" | 33x42 × 20x27 | 34.5 | 20 | 44.5 | 21 | 18 | 51 | 20 | 0.169 |
| 1"1/4 × 1" | 33x42 × 26x34 | 34.5 | 26 | 45 | 21.5 | 19.5 | 52 | 20 | 0.173 |
| 1"1/2 × 1/2" | 40x49 × 15x21 | 40 | 14.5 | 50.5 | 22 | 17 | 51 | 20 | 0.207 |
| 1"1/2 × 3/4" | 40x49 × 20x27 | 40 | 20 | 51 | 22 | 18 | 51.5 | 20 | 0.211 |
| 1"1/2 × 1" | 40x49 × 26x34 | 40 | 26 | 50.5 | 21 | 19 | 52.5 | 20 | 0.213 |
| 1"1/2 × 1"1/4 | 40x49 × 33x42 | 40 | 35 | 50.5 | 22 | 21 | 55 | 20 | 0.214 |
| 2" × 3/4" | 50x60 × 20x27 | 51.5 | 20 | 62.5 | 26 | 18.5 | 57.5 | 20 | 0.312 |
| 2" × 1" | 50x60 × 26x34 | 51.5 | 26 | 62.5 | 26 | 19.5 | 57.5 | 20 | 0.318 |
| 2" × 1"1/4 | 50x60 × 33x42 | 51.5 | 34.5 | 62.5 | 26 | 21.5 | 60 | 20 | 0.321 |
| 2" × 1"1/2 | 50x60 × 40x49 | 51 | 40 | 62.5 | 26 | 22.5 | 60.5 | 20 | 0.329 |
| 2"1/2 × 1"1/2 | 66x76 × 40x49 | 64.5 | 40 | 77.5 | 31 | 22.5 | 66 | 20 | 0.575 |
| 3" × 2"1/2 | 80x90 × 66x76 | 77.5 | 64.5 | 91.5 | 33 | 30.5 | 77.5 | 20 | 0.839 |
Size conversion
Conversion between the French size designation, inches, DN and the outside diameter stated in the designation (a rounded value, not a pipe dimension).
| French size | 5x10 | 8x13 | 12x17 | 15x21 | 20x27 | 26x34 | 33x42 | 40x49 | 50x60 | 66x76 | 80x90 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Inches | 1/8" | 1/4" | 3/8" | 1/2" | 3/4" | 1" | 1"1/4 | 1"1/2 | 2" | 2"1/2 | 3" |
| DN | DN6 | DN8 | DN10 | DN15 | DN20 | DN25 | DN32 | DN40 | DN50 | DN65 | DN80 |
| OD (French size) | 10 mm | 13 mm | 17 mm | 21 mm | 27 mm | 34 mm | 42 mm | 49 mm | 60 mm | 76 mm | 90 mm |
Stainless steel reducing nipple: frequently asked questions
Reducing nipple or male/female reducing bush?
The reducing nipple has two male ends: it joins two tapped ports. The stainless steel male/female reducing bush has only one male end, on the larger size, and takes a male thread of the smaller size. At 1" × 1/2", the reducing nipple is 47 mm long and the reducing bush 27 mm.
What is the internal bore?
The narrowest point is the bore at the small end, ØB. At 1" × 1/2", ØA is 26 mm and ØB 14.5 mm.
What is the pressure rating at 100 °C?
≈ 16.5 bar, against 20 bar from −20 to 40 °C.
316 or 304 stainless steel?
This reducing nipple is 316 (CF8M). Unlike 304, 316 contains molybdenum and has better resistance to chlorides.
The appearance of the part may vary depending on the batch in stock. Contact us for confirmation.
See also
Full range: all stainless steel BSP fittings
Other stainless steel fittings: stainless steel male/male nipple, stainless steel male/female reducing bush, stainless steel union PN 20.
Other materials: brass reducers, black malleable iron reducers.
Useful guides:
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