Live-Loaded packing is a methodology for maintaining steady pressure on a specific gland force that is caused by thermal cycling, pressure surges, packing relaxation, wear or extrusion. EGC has developed a data sheet for all valves providing assistance in accumulating the right dimensions and company data.
The valve stem is an integral part of the valve which converts actuating force into an open and closed motion. Between the valve stem and the valve bonnet, there exists a gap which must be sealed to stop fluid leaks from escaping into its surroundings.
The seal consists of gland packing and loaded by a gland bushing while multiple stud bolts are used to maintain constant pressure. But, due to gland wear or pressure surges, constant pressure cannot be maintained over time without re-tightening every bolt in every valve throughout the plant. This is unfeasible.
Requiring some mechanical arrangement to ensure steady pressure, EGC engineers decided on Belleville spring washers. The Belleville spring is a conically shaped disc that flattens or deflects at a given rate. It is used in combination with EGC graphite stem packing.
The Belleville spring washers are inserted on the stem OR on the fasteners and press against the check-nuts and the flange to maintain constant pressure on the gland packing. The Belleville spring washers has a high spring rate, can resolve thermal expansion and produce extremely high loads in a small area. In addition, they absorb shock, provide dampening and support extreme forces in bolted areas.
The EGC Live-Loaded data sheet can be completed either online or by a downloadable form which can be emailed to EGC. It consists of normal company data including the plant, contact name, phone numbers and email. The actual valve measurements consist of valve pressure class, operating temperature and, specific to Belleville springs, the inside diameter of the stuffing box and the outside diameter of the stem. EGC can engineer, manufacture and ship with a standard, 48 hour lead time just like our VSG Graphite Pressure Seals.
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