Between 2011 and early 2012, a refinery suffered repeat failures of a pair of vertical pumps. Looking at the cross section, you can see this is not an ordinary pump. It is essentially a BB5 multi-stage diffuser pump mounted vertically.
The pumping conditions are also uncommon–0.61 specific gravity hydrocarbon running at 300 F (149 C). The vapor pressure is nearly 50 psi (3.3 bar), well into the range of a flashing hydrocarbon.
In short, not an easy application–a vertically mounted, multi-stage, barrel pump in a hot, light, flashing, low viscosity hydrocarbon.
Repeat Pump Failures
The pumps were failing due to seizure of the original metal parts, which were 12% chrome alloy with a hardness difference. At the point where the refinery contacted Boulden, the pumps had failed several times in the previous year.
The engineers at the plant had heard that Vespel® CR-6100 wear parts would not seize. They discussed with Boulden that the material could handle the service conditions. The temperature limit for Vespel® CR-6100 is 500 F (260 C) and it resists all hydrocarbons without issue, so this application was well within the capabilities of Vespel® CR-6100. After several failures with the metal parts, the refinery decided to go forward with Vespel® CR-6100.
Vespel® CR-6100 wear rings, inter-stage rings, and throttle bushings were installed. Clearance at the wear rings was reduced to approximately 50% API recommended values for metal parts. A year later, the spare pump was also upgraded.
Results of Upgrading to Vespel® CR-6100
The first pump finally came out of service in early 2021 after nearly 9 years. From the look of the components, the Vespel® CR-6100 survived some really tough conditions. There was evidence of running dry, hard contact between rotating and stationary parts, and local temperatures well over 300 F (149 C). Yet, the pump never seized, and the Vespel® CR-6100 parts remained in usable condition all the way to the end of the run.
The MTBR for these pumps went from a few months to 9 years with a simple upgrade to Vespel® CR-6100. The investment in Vespel® CR-6100 has probably paid for itself 100 times over. The pumps clearly last longer, are easier to operate, and arguably much safer because they do not seize in this hot, flashing hydrocarbon service.
Do you have an application more difficult than this? Tell us about it.
Take your next repair as an opportunity to upgrade your pump. Boulden has a large inventory of material in stock and we can supply raw material or finished parts with very short lead times. We can provide all of the technical support required for you or your preferred workshop to make the upgrade a success.
Whatever the temperature, chemical, or operating conditions, it is likely that Boulden has a non-seizing, non-galling composite material to help you improve your pump reliability. Contact us today with the process conditions and we will let you know what we can do.