Stainless steel union, female/female 316L, PN 40, 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, female/female 316L, PN 40, BSP threaded
Stainless steel union, female/female 316L, PN 40, tapped BSP (Rp to ISO 7-1) at both ends, from 1/2" to 2" (DN15 to DN50). This machined conical (taper) seat union provides a point of disconnection on threaded pipework. PN 40, drinking water compliant, for all fluids compatible with stainless steel.
Description of the machined stainless steel union 316L PN 40
This 3-piece stainless steel union consists of two 316L stainless steel ends and a CF8M stainless steel nut. 316L is the low-carbon version of 316. At the conical seat, the seal is metal to metal between the two ends. Undoing the nut opens the joint without unscrewing the connected pipework.
One end is 6-sided; the other is cylindrical on the outside, with spanner flats. Both ends are Rp tapped: the cylindrical side is not a weld end.
Does your working pressure stay within the PN 20 limits? See the stainless steel union 316 PN 20, from 1/4" to 4".
Stainless steel union 316L PN 40: technical specifications
| Material | 316L stainless steel ends, CF8M stainless steel nut |
| Manufacture | Machined conical (taper) seat union |
| Standard | ISO 4144 |
| Type | 3-piece: two ends and a nut |
| Seal at the seat | Metal to metal |
| Shape | One end 6-sided, the other cylindrical with spanner flats |
| Thread | Rp tapped (parallel) at both ends, to ISO 7-1 (BSP). Mates with an R male thread (taper). Not compatible with NPT |
| Connection | Female/female |
| Nominal pressure | PN 40. Permissible pressure falls as temperature rises |
| Temperature | Stated range −20/+220 °C, with no high-temperature pressure values: consult us for hot applications |
| Fluids | All fluids compatible with stainless steel |
| Sizes | 6 sizes, from 1/2" to 2" |
| Compliance | 4MS; drinking water: French order of 25 June 2020 |
Pressure and temperature
This union is rated PN 40. The permissible pressure falls as temperature rises, and we have no high-temperature pressure curve for this part. The stated range of −20 to +220 °C therefore does not mean PN 40 across the whole range. For hot applications, contact us before choosing.
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 stainless steel, wherever a component must stay removable. Check the fluid’s compatibility with 316L and CF8M.
- Thread sealing: an Rp/R joint seals on the threads, using PTFE or jointing compound suited to the fluid and the working temperature.
- Conical seat: it seals metal to metal. Keep it clean on assembly and at every reassembly.
- Galling: with stainless steel on stainless steel, the thread can gall. Screw in gradually, without forcing.
- Tightening: hold the end with an open-ended or adjustable spanner on its hexagon or spanner flats and tighten the nut the same way, 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. Allow for this when choosing the connected components.
Technical drawing
Dimensions (mm)
Dimensions in millimetres, PN in bar, weight in kilograms.
| Rp size | French size | M1 | M2 | L | PN (bar) | Weight (kg) |
|---|---|---|---|---|---|---|
| 1/2" | 15x21 | 16 | 9 | 37 | 40 | 0.151 |
| 3/4" | 20x27 | 17 | 9 | 38 | 40 | 0.194 |
| 1" | 26x34 | 18 | 9 | 44 | 40 | 0.332 |
| 1"1/4 | 33x42 | 18 | 10 | 46 | 40 | 0.410 |
| 1"1/2 | 40x49 | 18 | 10 | 50.5 | 40 | 0.768 |
| 2" | 50x60 | 20 | 12 | 54 | 40 | 0.964 |
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 | 15x21 | 20x27 | 26x34 | 33x42 | 40x49 | 50x60 |
|---|---|---|---|---|---|---|
| Inches | 1/2" | 3/4" | 1" | 1"1/4 | 1"1/2 | 2" |
| DN | DN15 | DN20 | DN25 | DN32 | DN40 | DN50 |
| OD (French size) | 21 mm | 27 mm | 34 mm | 42 mm | 49 mm | 60 mm |
Stainless steel union 316L PN 40: frequently asked questions
PN 40 or PN 20?
The choice depends on the working pressure at the working temperature. A PN 20 union is not suitable if your installation requires PN 40. The PN 20 union covers 1/4" to 4", with published high-temperature values. This PN 40 union covers 1/2" to 2".
What is the pressure rating at high temperature?
We have no figure for this part. The permissible pressure falls as temperature rises. Contact us with the size, fluid, temperature and working pressure.
Is the cylindrical side a weld end?
No. Both ends are Rp tapped. This side is simply cylindrical on the outside, with spanner flats.
BSP or NPT thread?
BSP to ISO 7-1: Rp parallel tapped thread, for use with an R taper male thread. 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: stainless steel union 316 PN 20, stainless steel 90° female/female elbow, stainless steel female/female coupling.
Other materials: brass fittings, black malleable iron unions.
Useful guides:
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