Mill-Pro offers a wide range of injection moulded and fabricated tee pieces including:

• Injection Moulded Electrofusion Tees 
• Injection Moulded Spigot Tees 
• Electrofusion Saddles 
• Fabricated Tees.

Injection moulded Electrofusion Tees are used for smaller diameter pipelines (≤ 315 OD). Moulded in a single shot and in both equal and reducing offtakes.  They do not contain angled butt welds and do not require de-ration. 

Injection moulded Spigot Tees are moulded in a single shot and are available in sizes up to dn 630 in equal and reducing offtakes.  They do not contain angled butt welds and do not require de-ration.

Electrofusion saddles are ideal for smaller diameter takeoffs in larger size mains where cutting in a Tee causes significant disruption and cost. Saddles can be used to conduct live cut-ins to existing pipelines and install air valves in locations where clearance above the pipe crown is limited. 

Fabricated Tees in sizes from dn355 are manufactured by CNC machining a 'Fitting Body' from extruded hollow PE bar then pipe spigots are factory butt-welded on.  The required tee reinforcement is incorporated directly into the fitting body during machining, therefore they do not require de-ration (see Fig.1 below). Any custom tee design can be made in any size, including reducing, scour and angled off takes.  Fabricated tees are ideal for use in valve and pump chambers, where unique one-off components can be manufactured, eliminating Ductile Iron fittings to reduce long term maintenance.

Note: The specifications for fabrication and type testing for the supply of fabricated fittings to ensure their performance, are given in the Hong Kong Drainage Services Department, Appendix 5A, Clause 5.5.7.

Segmented Tees are prohibited in the Hong Kong Drainage Supplies Department (DSD) network. DSD Appendix 5A, Clause 5.5.6 prohibits the use of segmented tees. A segmented Tee is manufactured by cutting PE pipe at a 45º angle and butt welding the pipe segments together (described in BS EN 12201-3 Annex B5).  Refer fabricated bends Fig.2 for a more detailed explanation of de-ration). According to BS EN 12210-3 Annex A, Figure B.4 A segmented Tee fabricated from PN10 pipe must have a de-rating factor of 0.6x (60%) applied to the original pipes PN rating, so a PN10 Segmented Tee is derated to PN6.  This makes a segmented tee, fabricated from PN10 pipe, unusable in a PN10 rising main. 

Fig. 1 - Manufacturing process for fabricated fittings

• PE100+ compound is extruded into 'hollow bar' in various diameters and thicknesses to provide feed stock for machining. Extruded hollow bar is a void free. This may not be the case with 'mandrel wrapped' hollow bar.
• Hollow bar is machined into a 'fitting body' shape. This forms the core of the fitting, including structural reinforcement. Reinforcement design is proprietary, so Type Testing is used to confirm performance.
• The completed fitting body has two pipe spigots factory butt welded onto the mainway, and a smaller spigot butt welded at 90º to create the off take for connection on site, by electrofusion or butt fusion.
• Fabricated tees are custom one of fabrications. They allow unique designs such as large reductions in this example, which provide extremely compact designs. Any size reduction or shape can be manufactured.

As the design options for fabricated fittings are unlimited, it's not possible to provide tables on every option available. However, sizes up to DN700 are shown in accordance with the WSD PS and sizes up to DN/OD 2000 are available. For more information on fabricated fitting designs not shown contact us to assist with your requirements.

Photo credits: Reinert-Ritz world leaders in the manufacture of fabricated PE fittings for water and wastewater.

Click below, to see the complex design and rehabilitation solutions delivered using large-diameter fabricated PE fittings. Reinert-Ritz.pdf