Stainless steel union, male/female 316, PN 20, BSP threaded
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Shipping and Delivery
| Product Type | Delivery Method | Preparation Time | Transport Time | Delivery Time |
|---|---|---|---|---|
| All Parts | Pickup Point | 0 to 3 days | 3 to 6 days | 3 to 9 days |
| All Parts | Home Delivery | 0 to 3 days | 3 to 5 days | 3 to 8 days |
| Tubes > 90cm | Home Delivery | 0 to 3 days | 3 to 5 days | 3 to 8 days |
| Tubes < 200cm | Home Delivery | 0 to 3 days | 3 to 5 days | 3 to 8 days |
| Tubes > 200cm | Home Delivery | 0 to 6 days | 6 to 10 days | 6 to 16 days |
| Assembled Products | Home Delivery & Pickup Point | 0 to 5 days | (see methods) | 3 to 11 days |
* Tubes longer than 90cm cannot be delivered to a pickup point
For orders of more than 50 units of the same item or more than 100 kg, restocking may exceptionally extend the delivery time by up to 10 working days.
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Stainless steel union, male/female 316, PN 20, BSP threaded
Stainless steel union, male/female 316, PN 20, threaded BSP to ISO 7-1: R male at one end, Rp tapped at the other, from 1/4" to 4" (DN8 to DN100). This 3-piece conical (taper) seat union screws into a tapped port and provides a point of disconnection. PN 20 up to 40 °C, drinking water compliant, for all fluids compatible with stainless steel.
Description of the stainless steel male/female union PN 20
This 3-piece stainless steel union consists of two ends and a nut. The seal between the ends is metal to metal, at the conical seat. With the nut undone, the joint opens without unscrewing the pipework.
It is investment cast (lost wax) in CF8M (AISI 316) stainless steel, to the ISO 4144 standard. The ends have flats (dimension A). The nut (dimension B) has 8 sides from 1/4" to 3/4" and 10 sides from 1" to 4".
Need a weld end on one side? See the stainless steel union, male/butt weld, PN 20.
Stainless steel male/female union PN 20: technical specifications
| Material | CF8M (AISI 316) stainless steel |
| Manufacture | Investment casting (lost wax) |
| Standard | Designed, manufactured and inspected to ISO 4144 |
| Type | Conical (taper) seat union, 3-piece: two ends and a nut |
| Seal at the seat | Metal to metal |
| Shape | Ends with flats, nut with 8 or 10 sides depending on size |
| Thread | Male end: R (taper), mates with an Rp female thread. Female end: Rp tapped (parallel), mates with an R male thread. To ISO 7-1 (BSP, R series). Not compatible with NPT |
| Connection | Male/female |
| 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 | 11 sizes, from 1/4" to 4" |
| 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 union is used on drinking water systems and on circuits carrying fluids compatible with 316 stainless steel, wherever a component must stay removable. 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 temperature.
- Conical seat: keep it clean at every assembly.
- Galling: with stainless steel on stainless steel, the thread can gall. Screw in gradually, without forcing.
- Tightening: use an open-ended or adjustable spanner on the flats of the end and the nut, not 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.
Technical drawing
Dimensions (mm)
Dimensions in millimetres, PN in bar, weight in kilograms. A and B: across-flats dimensions of the end and the nut. ØC: inside diameter at the male end. L1: from the female face to the shoulder on the male end. L2: length of the nut. L3: length of the male thread. L1 + L3: overall length. A and B for the 1/4" and 3/8", and L1 for the 3", are not currently available: contact us if you need them.
| Rp/R size | French size | A | B | ØC | L1 | L2 | L3 | Nut sides | PN (bar) | Weight (kg) |
|---|---|---|---|---|---|---|---|---|---|---|
| 1/4" | 8x13 | – | – | 8 | 34 | 13.5 | 11 | 8 | 20 | 0.078 |
| 3/8" | 12x17 | – | – | 11.5 | 33 | 15.5 | 13 | 8 | 20 | 0.110 |
| 1/2" | 15x21 | 26 | 37 | 15 | 40 | 16.5 | 15 | 8 | 20 | 0.157 |
| 3/4" | 20x27 | 31 | 46 | 20.5 | 45 | 17.5 | 16 | 8 | 20 | 0.229 |
| 1" | 26x34 | 38 | 52 | 26 | 52 | 20.5 | 16.5 | 10 | 20 | 0.308 |
| 1"1/4 | 33x42 | 48 | 65 | 34.5 | 55 | 22.5 | 21 | 10 | 20 | 0.527 |
| 1"1/2 | 40x49 | 54 | 70 | 40 | 58 | 24 | 21 | 10 | 20 | 0.595 |
| 2" | 50x60 | 66 | 84.5 | 51 | 65.5 | 27 | 25.5 | 10 | 20 | 0.981 |
| 2"1/2 | 66x76 | 82 | 108 | 65.5 | 74 | 29 | 26.5 | 10 | 20 | 1.659 |
| 3" | 80x90 | 95.5 | 116.5 | 77.5 | – | 31.5 | 29.5 | 10 | 20 | 2.062 |
| 4" | 102x114 | 120.5 | 141 | 99 | 112 | 35 | 37 | 10 | 20 | 2.660 |
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 | 8x13 | 12x17 | 15x21 | 20x27 | 26x34 | 33x42 | 40x49 | 50x60 | 66x76 | 80x90 | 102x114 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Inches | 1/4" | 3/8" | 1/2" | 3/4" | 1" | 1"1/4 | 1"1/2 | 2" | 2"1/2 | 3" | 4" |
| DN | DN8 | DN10 | DN15 | DN20 | DN25 | DN32 | DN40 | DN50 | DN65 | DN80 | DN100 |
| OD (French size) | 13 mm | 17 mm | 21 mm | 27 mm | 34 mm | 42 mm | 49 mm | 60 mm | 76 mm | 90 mm | 114 mm |
Stainless steel male/female union PN 20: frequently asked questions
Male/female or female/female?
This union has one R male end and one Rp female end. The female/female union PN 20 takes an R male thread at each end.
PN 20 or PN 40?
The choice depends on the pressure at the working temperature. The male/female union 316L PN 40 covers 1/2" to 2", with no published high-temperature values: for hot applications, contact us. A PN 20 union is not suitable if your installation requires PN 40.
What is the pressure rating at 100 °C?
≈ 16.5 bar, against 20 bar from −20 to 40 °C.
BSP or NPT thread?
BSP to ISO 7-1: R taper and Rp parallel. This union is not compatible with NPT.
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: female/female union PN 20, male/female union PN 40, male/male nipple.
Other materials: brass fittings, black malleable iron unions.
Useful guides:
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