Because of the difficulties of dealing with slurry as a medium, the equipment assigned to move it along faces many challenges. One that gets lost among a host of others for slurry valves is packing. While packing-less valves (such as pinch valves) exist, most valves have a stuffing box and need packing to create a seal against the stem or gate. Proper packing selection, failure analysis and installation procedures are critical to the leak-free operation of valves.

Welding and valves officially became joined at the hip with the perfection of the arc-welding process in the late 1920s. Up until then, every component in a valve was made of solid, homogeneous material, and all the end connections were either threaded or flanged.

Increased emphasis on the need to improve process performance and reduce variability mean many control loops today are optimized. This is done through digital adaptive control and predictive control algorithms in distributed control systems or programmable logic controllers. These advanced control routines make it easy to linearize control valve performance and get the most out of assets. They do not, however, guarantee accurate and repeatable input values from all the primary measuring instruments. That’s why when measuring flow, one of the easiest and most economical ways to ensure that process improvements are what we expect is to make sure our flow devices have a happy home. Let me explain:

Cobalt-based Stellite 6 has been the workhorse for providing improved wear resistance and service life in valve components installed in power generating facilities for over 75 years. However, documented failures at combined cycle and supercritical power stations suggest that new materials and new (or refined) hardfacing processes are needed as the industry continues to move toward the higher operating temperatures in ultrasupercritical (USC) and advanced ultra-supercritical applications (A-USC).