Telescoping valves are used primarily for sludge removal, or liquid level control, and are considered to be fully open when in the lowermost position. The valve tube travels inside a cast iron or stainless steel riser pipe as shown in the plan drawings provided by the customer. The nominal riser pipe diameter determines the valve tube diameter. Vee notch, flared, or baffled tube tops shall be provided when required by the plan drawings. Valves shall be Waterman or approved equal in quality, characteristics and performance, of a manufacturer regularly engaged with a previous experience in manufacturing similar valves.
Stainless steel or steel tubes up through 24” size shall be manufactured from seamless pipe or tube. Steel tubes are to be epoxy coated. Tube lengths shall be as shown or noted on the drawings and must be of sufficient length to facilitate valve travel and maintain an appropriate insert depth. Valve tubes are to be a minimum 3mm thick and are attached to connecting stems by use of a lifting bail.
A stainless steel companion flange and neoprene slip seal gasket shall be provided. The gasket must be a minimum 3mm thick. The inside diameter of the gasket is to be 1/8" smaller than the outside diameter of the valve tube to provide a friction seal. The gasket is to be sandwiched between the riser pipe flange and the companion flange. The gasket and companion flange shall include a 125# standard drilling pattern to match the riser pipe.
The bail shall be the same material as the tube and be rigidly welded to the tube.
LIFT AND STEMS (RISING)
Lifts shall be handwheel type, with a stub acme threaded type 304 or 316 stainless steel stem to provide automatic self-locking, infinite valve positioning. The standard rising stem lift shall use a galvanized steel square tube with torque nut design to prevent telescoping valve tube rotation. Alternately, where conditions require, a vee keyed shaft, with torque plate, shall be used to prevent valve tube rotation. Handwheels shall be a minimum of 300mm diameter and shall include a clear plastic stem cover with a Mylar strip type position indicator, graduated in 10mm increments to illustrate valve position. The Mylar strip shall be affixed by the contractor after installation to provide a true and accurate indication of the tube elevation by comparing it to the top of the rising stem. Stainless steel anchor bolts shall be provided for all pedestals.
LIFT (NON-RISING STEM)
Lifts shall be handwheel type with position indicator, mounted to a fabricated steel non-rising stem pedestal. The pedestal shall be manufactured with a square, main vertical member and a telescoping type torque tube. The torque tube shall incorporate a square thrust pocket at the top to house a square thrust nut, to prevent rotation of the valve tube assembly. The bottom of the torque tube shall be attached to the lifting bail with bolts & nuts, same as rising stem lift.
Where mounting conditions do not permit standard rising or non-rising stem lifts, a non-rising stem telescoping valve shall be provided. The valve bail design shall include nut pocket for NRS
-2- thrust nut and guides to prevent tube rotation. Stems shall be stub acme threaded type 304 or 316 stainless steel non-rising stem, threaded and keyed to either pedestal mounted type lift, or floor box type lift. Lift shall have a position indicator and 2” square nut to be operated by T-handle.