The durability and performance provided by John Crane mechanical seals has been proven during a recent scheduled maintenance shut down at a paper plant in Canada. A John Crane Safematic seal has been removed from the plant as a preventative maintenance measure after providing no less than six years of reliable, leak-free service. This achievement is all the more remarkable as the seal was fitted to a pressure screen that is one of largest of its kind in the world, and when removed the seal faces were in good shape with only minimal signs of wear. The Domtar mill in the city of Dryden, Ontario, produces uncoated free–sheet paper. In 2001 the mill installed a Valmet TLA-1800 pressure screen to feed stock to its paper machine. A John Crane Safematic SAF 230 TREN seal was fitted to a 230mm diameter shaft, which serves this screen, and despite operating in the demanding environment of a paper mill the John Crane seal has handled a rotation speed of 92.4rpm and a pressure of 323Kpa for six years, without a single problem. A number of other John Crane Safematic products in use on this process also contributed to the seal’s impressive operational life. A constant supply of water is required to lubricate and cool the seal. This is drawn from the nearby Wabigoon River and passes through a John Crane Safematic Safefilter system before being piped into a Safeunit SFD 08 10 – AC-1, which controls the flow to the double seal as well as the back-pressure in the seal chamber. After lubricating the seal faces and dissipating heat the water flows back to the Safeunit before being piped away to drain.