Saddle Taps

ATS Saddle Taps on Non-Operating Systems

Part Types #39 & 49

Place saddle tap against main duct at the exact location where it will be installed. Mark the centerline of the tap on the duct for alignment. Using a marker (wax pencil or china marker) inscribe the inside diameter and outside of the saddle flange.

Using a jigsaw with a carbide tip or carborundum blade, cut approximately 8mm (3/8”) outside of the tap diameter line drawn on the duct. This creates a hole for the tap which is slightly larger than the interior of the tap allowing a lip for the ChemBond™ putty to fill, sealing the cut edge of the main duct. ATS Saddle Taps come pre-sanded on the interior from the factory.

Apply ChemBond™ putty to the underside of the saddle. The putty should be about 3mm (1/8”) thick. Also apply putty mix to the cut edge of the main header duct. The tap is then placed on the main duct using the saddle centerline marks drawn previously. Stainless steel hose clamps should be used to secure the tap to the main until the putty has cured. As the hose clamps are lightly tightened, putty will ooze out from under the saddle, both on the inside and outside seams. On 3” diameter (75mm diameter) and greater, the inside of the joint can be beveled by hand. By hand, reaching inside the tap, smooth the putty on the interior to create a beveled surface.

The stainless steel hose clamps should be left on the duct for shear strength while the ChemBond™ putty is curing. *Note: Hose clamps are not supplied by ATS.

If stainless steel hose clamps are left on, no further work needs to be done. However, if it is desirable to remove the hose clamps, an additional outside layup is recommended if the duct is 14” greater (due to the weight of the taps).

(If doing outside layups, apply boat cloth to a resin-rich saddle and main duct surface. Use the chart below to determine correct number of layers and glass width. Sanding of the exterior of the Saddle Tap and the main is required for diameters greater than 40” (1000mm) diameter to ensure good adhesion. Use the Saddle Tap Glass Chart below as a guide.)

Nom. Diam. mm  Nom. Diam. Inch  # of Glass Layers Wetted with ChemBond™ Resin
Width of Boat Cloth
100 (4″) 150 (6″) 200 (8″) 300 (12″)
50–300 2”–12” Not Required
350–600 14”–24” 1 1
650–1000 26”–40” 1 1 1
1050–1500 42”–60” 1 1 1
 > 1500 > 60” 1 1 1 1