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The weld-on tailpiece from Danfoss is an accessory designed for the direct connection of seat control valves to steel pipework. The tailpiece allows secure, leak-tight welding to the piping system with a nominal diameter of DN 20, while on the valve side it is connected by means of a G 1" female parallel thread. More information
Out of stock - can be requested
| Connection size | G 1" |
| Connection Type | Internal thread |
| Nominal diameter | DN 20 |
| Pressure | 25 bar |
| Weight | 0.33 kg |
Danfoss 003H6909 weld-on end connection is a two-piece straight assembly designed for the permanent connection of Danfoss globe control valves to steel pipework by welding. The union part with internal parallel thread G 1" is made of brass, while the weld-on plain end (Ø 20 mm) is made of St 35 / 1.0308 steel. Both parts are supplied without surface treatment and together form a single assembly for nominal diameter DN 20.
The weld-on end connection is used in industrial steam distribution systems, hot-water systems and heat exchanger stations where Danfoss PN 25 globe valves are installed. It is typically fitted with VGS series valves (two-way valves for steam and hot water up to 200 °C) or AVA valves (self-acting differential pressure controllers for district heating systems). A welded connection is chosen where, for design or operating reasons, it is more suitable than a threaded or flanged version - especially in permanent installations in metal pipework with high requirements for leak-tightness and joint strength.
Technical parameters:
The 003H6909 end connection is system-specific and is designed exclusively for Danfoss globe valves of the corresponding DN 20 size with nominal pressure PN 25. In Danfoss documentation, it is explicitly listed as an accessory for VGS valves (two-way valves for steam, PN 25) and AVA valves (self-acting differential pressure controllers). Always verify suitability for the specific valve type in that valve's technical data sheet or with the sales department.
The plain steel end (Ø 20 mm) is inserted into the steel pipe and welded using a standard welding procedure for St 35 steel. The brass union part with G 1" thread is then screwed onto the valve outlet thread. The weld provides a permanent, leak-tight connection to the pipework. Installation should be carried out by a person with the appropriate welding qualification for the material concerned.
The body of Danfoss VGS globe valves is made of red bronze (CuSn5ZnPb / Rg5), and the thread in the brass union part of the end connection has a compatible thread profile. By contrast, the weld-on plain end must be made of steel so that it can be welded to standard steel pipework (St 35 is a weldable carbon steel). This bimetal assembly therefore connects the different materials of the pipework and valve, while both joints - the weld and the thread - meet operating conditions up to 25 bar.
For PN 25 globe valves in DN 20 size, Danfoss also offers threaded end connections with external taper thread R ¾" to EN 10226-1 (code 003H6903) and flanged end connections PN 25 to EN 1092-2 (code 003H6916). The 003H6909 weld-on version is selected where a permanent welded joint is required - typically for new installations in steel pipework. The threaded and flanged variants allow easier removal of the valve during maintenance.
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