Stainless steel blanking plug, male 316, 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 |
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Stainless steel blanking plug, male 316, BSP threaded (R taper to ISO 7-1), with flats on the head. It screws into an Rp tapped thread to close an unused female outlet or one left for future connection, for example on a tee or a cross. Available from 1/4" to 4" (DN8 to DN100), PN 20 up to 40 °C, drinking water compliant, for all fluids compatible with stainless steel.
Description of the stainless steel male BSP blanking plug
This stainless steel threaded plug has a taper R male thread, extended by a head with flats for tightening with a spanner. It is investment cast (lost wax) in CF8M (AISI 316) stainless steel, and designed, manufactured and inspected to ISO 4144.
The part is not solid: it is hollow on the thread side (dimension ØC) and the head closes the end. The plug comes in 11 sizes, from 1/4" (French size 8x13) to 4" (102x114). To close a male end rather than a tapped thread, see the stainless steel female end cap.
Stainless steel male blanking plug: technical specifications
| Material | CF8M (AISI 316) stainless steel |
| Manufacture | Investment casting (lost wax) |
| Standard | Designed, manufactured and inspected to ISO 4144 |
| Shape | Head with flats, body hollow on the thread side |
| Thread | R male (taper) to ISO 7-1 (BSP, R series). Mates with an Rp female thread (parallel). Not compatible with NPT |
| Connection | 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 | 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 male blanking plug is used on drinking water systems and on circuits carrying fluids compatible with 316 stainless steel. For example, it closes the free outlet of a stainless steel equal tee, a stainless steel cross or a stainless steel 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 flats of the head, not with pipe grips or pliers, which mark stainless steel. If the tapped component has no flats, hold it with a strap wrench.
- Removal: depressurize and drain the system before unscrewing the plug.
- 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)
A is the dimension across flats of the head. The ØB column corresponds to dimension B on the drawing, the overall length of the part. ØC is the inside diameter on the thread side. Dimensions in millimetres, PN in bar, weight in kilograms. A and ØB for the 1"1/4, ØC for the 3/4", 1", 1"1/4, 1"1/2, 2", 2"1/2, 3" and 4", and ØB and the weight for the 4", are not currently available: contact us if you need them.
| R size | French size | A | ØB | ØC | PN (bar) | Weight (kg) |
|---|---|---|---|---|---|---|
| 1/4" | 8x13 | 14 | 15 | 8 | 20 | 0.014 |
| 3/8" | 12x17 | 19 | 19.5 | 11 | 20 | 0.023 |
| 1/2" | 15x21 | 23 | 23.5 | 14.5 | 20 | 0.037 |
| 3/4" | 20x27 | 28.5 | 26 | – | 20 | 0.057 |
| 1" | 26x34 | 35.5 | 29 | – | 20 | 0.084 |
| 1"1/4 | 33x42 | – | – | – | 20 | 0.126 |
| 1"1/2 | 40x49 | 51 | 31 | – | 20 | 0.167 |
| 2" | 50x60 | 66 | 34 | – | 20 | 0.265 |
| 2"1/2 | 66x76 | 78 | 39.5 | – | 20 | 0.477 |
| 3" | 80x90 | 92 | 40 | – | 20 | 0.643 |
| 4" | 102x114 | 122.5 | – | – | 20 | – |
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 blanking plug: frequently asked questions
Is the male plug solid?
No. It is hollow on the thread side, and the head with flats closes the end. Dimension ØC in the table, where given, is the inside diameter.
What does this plug screw into?
An Rp parallel tapped thread to ISO 7-1. It is BSP threaded and not compatible with NPT.
316 or 304 stainless steel?
This plug 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 female end cap, stainless steel female equal tee, stainless steel female cross, stainless steel female/female coupling.
Other materials: all caps and plugs, brass caps and plugs, black malleable iron caps and plugs.
Useful guides:
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