The leading association of utilities in Copenhagen City - HOFOR (formerly: Københavns Energi - had an acute problem with shaft seals in a counter-flap valve and it was crucial to get it back into operation as soon as possible. Grønbech & Sons talk about how they took this opportunity to build in new customer benefits.
The affected valve and pump were only activated in very heavy rain and the customer had previously experienced that the braided seals were losing volume, either because they had dried out or due to perishable additives in the seals. An acute leak around the valve spindle is problematic. This leads to non-scheduled stoppage and inconvenience for the supply company’s customers. The existing seal was of unknown type. The waste water chemical characteristics were not uniform and long standstill periods for the connected pump meant that the risk of drying out represented a special challenge for the seals’ sealing ability.
We wanted to find the ideal packing material for the two DN 1200 counter-flap valves on the waste water treatment plant, but because of the emergency nature of the task, we were unaware of the condition of the spindle: The valve had been in operation for a long time and it had not yet been opened. Furthermore, the waste water that was routed through the valve contained various chemical residues. In consultation with Betech, I therefore recommended a product which would certainly be able to absorb any irregularities on the shaft/spindle and was resistant to chemicals.
By replacing the old gasket material with Slade™ gaskets in patented graphite yarn, the customer achieved sealing with proven long service life and minimal risk of leakage. A qualified choice of seal contributed to a more economical operation and less risk of acute repair work.
Slade™ graphite seals have no filler or additives and in combination with the patented graphite yarn they eliminate the need to install a costly and cumbersome “live loading”. Graphite gasket volume and sealing characteristics simply stay the same over time.
Another advantage of Slade™ seals is that same type of seal can be used for both pumps and valves. Actually, a single sealing cord, namely Slade™ 3300G, can be used for the majority of applications. It can for example be used for all applications at a power plant. This reduces material inventory and reduces the risk of selecting the wrong type of seal.
"Once Betech had been sent the relevant data, they were quick to present a solution. We did what they suggested and the valve shafts were once again sealed. It was an effective process and the result was also a very satisfied customer. In fact, they were so happy that they asked us to repack some of their other shaft seals as a preventive measure. High sealing characteristics and easy installation of the Slade™ seal gives security and the best results."
— Peter Lauridsen, Service Manager, Grønbech & Sønner