Stainless steel union, female/butt weld 316L, PN 40, BSP threaded
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| 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
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Stainless steel union, female/butt weld 316L, PN 40, BSP threaded
Stainless steel union, female/butt weld 316L, PN 40, machined, from 1/2" to 2" (DN15 to DN50): its BSP tapped end (Rp to ISO 7-1) takes an R male thread, its plain end is butt welded (BW) to the pipe, and the nut undoes to open the joint. PN 40, drinking water compliant, for all fluids compatible with stainless steel.
Description of the machined stainless steel union, female/butt weld 316L PN 40
This 3-piece stainless steel union combines 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. Dismantling the union requires neither cutting the pipe nor unscrewing the threaded component.
The female end is 6-sided. The BW end is plain and is butt welded: its dimension Ø ranges from 21.3 to 60.3 mm.
Stainless steel female/butt weld union 316L: technical specifications
| Material | 316L stainless steel ends, CF8M stainless steel nut |
| Manufacture | Machined conical (taper) seat union |
| Standard | ISO 4144 |
| Type | 3-piece: a female end, a weld end and a nut |
| Seal at the seat | Metal to metal |
| Shape | 6-sided female end, plain weld end, nut with flats |
| Thread | Rp tapped (parallel) to ISO 7-1 (BSP). Mates with an R male thread (taper). Not compatible with NPT |
| Weld end | Plain BW end, for butt welding, Ø 21.3 to 60.3 mm |
| Connection | Female/butt weld |
| 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. Check the fluid’s compatibility with 316L and CF8M.
- 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.
Technical drawing
Dimensions (mm)
L: overall length. Ø: outside diameter of the weld end. Rp: tapped thread, Rp size column. M1: length of the nut. M3: length of the flats on the female end. Dimensions in millimetres, PN in bar, weight in kilograms.
| Rp size | French size | Ø | M1 | M3 | L | PN (bar) | Weight (kg) |
|---|---|---|---|---|---|---|---|
| 1/2" | 15x21 | 21.3 | 16 | 9 | 38 | 40 | 0.101 |
| 3/4" | 20x27 | 26.9 | 17 | 9 | 41 | 40 | 0.151 |
| 1" | 26x34 | 33.7 | 18 | 9 | 43 | 40 | 0.207 |
| 1"1/4 | 33x42 | 42.4 | 18 | 10 | 48 | 40 | 0.278 |
| 1"1/2 | 40x49 | 48.3 | 18 | 10 | 50 | 40 | 0.406 |
| 2" | 50x60 | 60.3 | 20 | 12 | 56 | 40 | 0.512 |
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 Ø.
| 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 female/butt weld union 316L: 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 version covers 1/4" to 2", with published high-temperature values.
What is the pressure rating at high temperature?
We have no figure for this part. Contact us with the size, fluid, temperature and working pressure.
Which parts are 316L?
Both ends, on the tapped side as well as the weld side. The nut is CF8M.
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 316L PN 40 for a tapped component, stainless steel butt weld union 316L PN 40 for welding at both ends, stainless steel female/female union 316L PN 40 for screwing at both ends.
Other materials: brass fittings, black malleable iron unions.
Useful guides:
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