When transferring high-pressure fluids, maintaining pump safety deserves extra attention. Seals and valves should properly function as pressures rise. If not, you face the risk of catastrophic equipment failure and a serious safety concern.
Valve Packing Maintenance
Proper valve packing maintenance is critical as part of an overall pump system maintenance schedule. Valve packing is a string sealant used to prevent leaks in valve stems and stuffing boxes. The packing strings usually contain polytetrafluoroethylene (PTFE) or graphite, making them pliable, self-lubricating, and durable. Proper packing will prevent leaks while also protecting the valves from wear. You must make sure you are using the correct type of valve packing. In addition, you should always replace the packing if it is getting worn.
Significant strain on the valve components and seals makes maintenance especially crucial in high-pressure applications. The first step is understanding your application and the exact temperature and pressure range you are dealing with when transferring a particular fluid.
Knowing the fluid pressures and temperatures will narrow down your packing options that withstand these extreme conditions with ample tolerance. PTFE-impregnated packing is not going to be ideal for all applicationsm since the temperature threshold is a limiting factor with PTFE. Your plant specifications may also dictate very specific limitations that will determine if PTFE packing can be used or not.
Actuation Frequency & Thermal Cycling
Other factors to look at are actuation frequency and thermal cycling. Some fluids create high actuation frequency or high thermal cycling conditions, resulting in problematic packing consolidation. Specific applications will benefit from “live loading” when you use Belleville springs on gland bolts. Live loading reduces load loss on packing, optimizing packing life and can minimizing the risk of catastrophic valve failure.
If thermal cycling is a recurring issue, you will also want to evaluate the valve stem material. Galvanic corrosion of the stem can happen, especially with applications that present frequent temperature cycles and moisture that weakens graphite packing. Sometimes, switching to a more corrosion-resistant valve stem material like 316 stainless steel is an effective solution.
Bolt materials will also impact safety, so they need solid tensile strength in high-pressure applications. However, their tensile strength decreases as temperatures approach 1000°F, so you will need specialized bolts with more heat-resistant materials like B8M.
Proper Maintenance of Bolts and Skive Cut Rings
Skive cut rings have ends cut at a 45-degree angle, which is ideal for high-pressure valves. The ends should line up perfectly for maximum effectiveness and prevention of leak paths. During installation and maintenance, tamp each ring to ensure they are correctly seated. Any open spaces may lead to packing consolidation. Other maintenance tips include keeping the joints 90 degrees apart and using anti-seize on bolts for proper bolt tension.
As you can see, there is more to your pump system valves than meets the eye. They perform a vital function in all pumping applications, and are especially important when dealing with high pressures and temperatures. Even so, they are a common failure point, which is why they deserve to be part of your preventative maintenance program. For all your pump installation, servicing, replacement valve parts, and packing maintenance needs, you can count on DXP Pacific. We’ll help you find the right stem, bolt, and packing materials for your high-pressure application. In addition, we provide professional installation, repair, and maintenance services to improve pump performance and increase the lifespan of your equipment.