Stainless steel union, male/butt weld 316L, PN 40, BSP threaded

$35.00

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Size

1/2" × Ø 21.3 mm 3/4" × Ø 26.9 mm 1" × Ø 33.7 mm 1"1/4 × Ø 42.4 mm 1"1/2 × Ø 48.3 mm 2" × Ø 60.3 mm

Product variants

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

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Stainless steel union, male/butt weld 316L, PN 40, machined, with one BSP threaded side (R taper to ISO 7-1) and one plain butt weld (BW) side. Available from 1/2" to 2" (DN15 to DN50), it connects an Rp tapped thread to a pipe by welding, and its nut lets you open the joint. PN 40, drinking water compliant, for all fluids compatible with stainless steel.

Description of the machined stainless steel union, male/butt weld 316L PN 40

This machined conical seat union consists of two 316L stainless steel ends (the low-carbon version of 316) and a CF8M stainless steel nut. Its nominal pressure is 40 bar (PN 40). The seal is metal to metal at the conical seat. Once the nut is undone, the joint opens without disturbing the pipe or the screwed component.

One end is 6-sided, the other has spanner flats. The BW end is butt welded, from Ø 21.3 to Ø 60.3 mm.

Stainless steel male/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 male end, a weld end and a nut
Seal at the seat	Metal to metal
Shape	One end 6-sided, the other with spanner flats, nut with flats
Thread	R taper to ISO 7-1 (BSP). Mates with an Rp female thread (parallel). Not compatible with NPT
Weld end	Plain BW end, for butt welding, Ø 21.3 to 60.3 mm
Connection	Male/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

It is used on drinking water systems and on circuits carrying fluids compatible with stainless steel. Check the fluid’s compatibility with 316L and CF8M.

BW side: have the weld made by a qualified welder. The welding process and filler metal depend on the installation. Separate the ends 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 end with an open-ended or adjustable spanner on its hexagon or spanner flats and tighten the nut the same way. Avoid pipe grips and pliers, which mark stainless steel.

Technical drawing

Dimensions (mm)

L: overall length. Ø: outside diameter of the weld end. R: male thread, R size column. M1: length of the nut. M4: drawing dimension, thread side. Dimensions in millimetres, PN in bar, weight in kilograms.

R size	French size	Ø	M1	M4	L	PN (bar)	Weight (kg)
1/2"	15x21	21.3	16	10	52	40	0.131
3/4"	20x27	26.9	17	10	56	40	0.194
1"	26x34	33.7	18	14	60	40	0.278
1"1/4	33x42	42.4	18	14	63.5	40	0.340
1"1/2	40x49	48.3	18	14	63.8	40	0.457
2"	50x60	60.3	20	17	74	40	0.641

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). For welding, the dimension that matters is 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 male/butt weld union 316L: frequently asked questions

PN 40 or PN 20?

Compare your working pressure with the permissible pressure at your temperature. A PN 20 union is not suitable if your installation requires PN 40. The PN 20 version starts at 3/8" and publishes its high-temperature values.

What is the pressure rating at high temperature?

No figure is available. Contact us with the size, fluid, temperature and working pressure.

What length should I allow?

Dimension L ranges from 52 mm at 1/2" to 74 mm at 2".

BSP or NPT thread?

BSP to ISO 7-1: R taper thread, for use with an Rp parallel female 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.

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