When installing anodes or reference electrodes into potable water tank interiors, access holes are commonly cut into the roof of the tank. These holes allow access for the suspension of the anodes or reference electrodes from the tank room. Typically, a 5" diameter opening is cut in the tank roof allowing adequate space for worker access.
Hand hole covers are used to close the access opening to prevent unwanted, foreign materials from entering the water tank. Provided in a variety of materials, hand hole covers are simple to use and relatively inexpensive. Each assembly consists of a 6" diameter cover plate, gasket, clamping bar and bolt and come in a variety of materials.
Each of the above assemblies include a standard 1/8" thick x 6" diameter neoprene sealing gasket.
A new, optional (see below) Hand-Hole Grommet is available that is 1/2" thick x 6" diameter neoprene with a 3/16" sealing surface. Once installed with a caulking material , the grommet never needs to be removed, which protects the painted surface of the tank and prevents surface corrosion.
This new Hand-Hole Grommet design helps to eliminate coating damage caused by the use of conventional hand-hole gaskets. Typically, standard rubber gaskets stick to newly coated tank surfaces and when the gasket is removed, the coating can be damaged allowing corrosion to occur. The Hand-Hole Grommet is installed permanently and never needs to be removed.
|With Standard Gasket||With Optional Grommet|
1. A 5" diameter access opening must be cut into the tank roof. This access opening is used to install suspension hardware, such as a electrical clevis assembly and to lower a cathodic protection anode or reference electrode into the interior of the tank.
2. Install the required suspension hardware near the 5" opening. Allow enough room between the 5" opening and the suspension hardware so the Hand Hole Cover Assembly will fit properly.
3. Repair the exterior and interior tank coating and allow the coating to dry.
4. After the anode is suspended from the appropriate suspension device, the Hand Hole Cover Assembly can be installed to seal the hole.
5. Assemble the Hand Hole Cover Assembly before installing into the 5" opening. Insert the bolt through the cover plate, the gasket (the gasket can be eliminated if you've purchased the optional grommet) and then thread the bolt into the clamping bar.
a. Leave some "slack" in the assembly so the clamping bar can be inserted into the tank opening.
b. After assembly, it's a good idea to scar or damage the bolt threads at the bottom of the bolt to keep the clamping bar from falling off the bolt when removed in the future. A file, hacksaw or similar can be used to damage the bolt threads.
6. Tighten the bolt head so that the tank roof is "sandwiched" between the clamping bar and the gasket and cover.