Stainless steel union, female/butt weld 316, PN 20, BSP threaded
Shipping and Delivery
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.
For confirmation of delivery times on specific items, please send us a message
Stainless steel union, female/butt weld 316, PN 20, BSP threaded
Stainless steel union, female/butt weld 316, PN 20, tapped BSP (Rp to ISO 7-1) at one end, with a plain butt weld (BW) end at the other, from 1/4" to 2" (DN8 to DN50). It connects an R male thread to a pipe by welding, while keeping 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 union, female/butt weld 316 PN 20, with conical seat
This 3-piece stainless steel union combines a female end with flats, a weld end and a nut. At the conical seat, the seal is metal to metal between the ends. Undoing the nut opens the joint without cutting the pipe.
The union is investment cast (lost wax) in CF8M (AISI 316) stainless steel, and designed, manufactured and inspected to ISO 4144. The BW end is butt welded: its dimension ØB ranges from 13.5 to 60.3 mm.
Does your working pressure exceed the PN 20 limit at your temperature? See the stainless steel union, female/butt weld 316L PN 40, from 1/2" to 2", which has no high-temperature figures: for hot applications, contact us before choosing.
Stainless steel female/butt weld union: 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: a female end, a weld end and a nut |
| Seal at the seat | Metal to metal |
| Shape | Female end with flats, plain weld end, nut with flats |
| Thread | Rp tapped (parallel) to ISO 7-1 (BSP, R series). Mates with an R male thread (taper). Not compatible with NPT |
| Weld end | Plain BW end, for butt welding, Ø 13.5 to 60.3 mm |
| Connection | Female/butt weld |
| 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 | 8 sizes, from 1/4" to 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 union is used on drinking water systems and on circuits carrying fluids compatible with 316 stainless steel. Check fluid compatibility and the permissible pressure at the working temperature.
- Welding: to be carried out by a qualified welder. The welding process and filler metal depend on the installation. Dismantle the union before welding to protect the conical seat.
- 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: hold the female end with an open-ended or adjustable spanner on its 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.
Technical drawing
Dimensions (mm)
A: overall length. ØB: outside diameter of the weld end. C: outside dimension of the nut. SW1: outside dimension of the female end with flats. Ø on the drawing: tapped thread, Rp size column. Dimensions in millimetres, PN in bar, weight in kilograms.
| Rp size | French size | A | ØB | C | SW1 | PN (bar) | Weight (kg) |
|---|---|---|---|---|---|---|---|
| 1/4" | 8x13 | 32.3 | 13.5 | 33 | 17 | 20 | 0.073 |
| 3/8" | 12x17 | 37.1 | 17.2 | 36.8 | 20.6 | 20 | 0.115 |
| 1/2" | 15x21 | 40.3 | 21.3 | 40 | 24.5 | 20 | 0.121 |
| 3/4" | 20x27 | 45.1 | 26.9 | 49.5 | 30.2 | 20 | 0.170 |
| 1" | 26x34 | 49.1 | 33.7 | 56 | 37.1 | 20 | 0.290 |
| 1"1/4 | 33x42 | 55 | 42.4 | 67.3 | 46 | 20 | 0.391 |
| 1"1/2 | 40x49 | 59 | 48.3 | 73 | 51.8 | 20 | 0.442 |
| 2" | 50x60 | 67.8 | 60.3 | 90 | 63.5 | 20 | 0.759 |
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). On the weld side, go by dimension ØB.
| French size | 8x13 | 12x17 | 15x21 | 20x27 | 26x34 | 33x42 | 40x49 | 50x60 |
|---|---|---|---|---|---|---|---|---|
| Inches | 1/4" | 3/8" | 1/2" | 3/4" | 1" | 1"1/4 | 1"1/2 | 2" |
| DN | DN8 | DN10 | DN15 | DN20 | DN25 | DN32 | DN40 | DN50 |
| OD (French size) | 13 mm | 17 mm | 21 mm | 27 mm | 34 mm | 42 mm | 49 mm | 60 mm |
Stainless steel female/butt weld union: frequently asked questions
What diameter on the weld side?
Dimension ØB gives the outside diameter of the end, to compare with that of your pipe. Approving the weld on that pipe is a matter for your welder.
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: 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 male/butt weld union PN 20 for a tapped component, stainless steel butt weld union PN 20 for welding at both ends, stainless steel female/female union PN 20 for screwing at both ends.
Other materials: brass fittings, black malleable iron unions.
Useful guides:
Payment & Security
Payment Method
Your payment information is managed securely. We do not store or have access to your credit card information.