Inadequate lubrication and dirt do not prevent multiphase pumps from operating efficiently when using diamond-faced mechanical seals.
by Andreas Goldschmidt & Tobias Gürtler, EagleBurgmann

Diamond-facing the bearing ring and stationary seat ensured that the sliding surfaces can withstand dry running for several minutes without damage and handle temperatures in the sealing gap of up to 300 C without problems. This was all possible without using complicated API Plan 32 systems. The diamond-faced mechanical seal is equipped to cope with abrupt fluctuations in the media content of the pumped mixture, which are common in multiphase applications. The spectrum ranges from pure gas to water or oil with differing solids contents.

Optimized Peripheral Issues

Even though diamond-faced seals were the ideal solution to handle the difficult conditions at Panacocha, a few details needed to be addressed. All the metal components of the preassembled cartridge were made from super-duplex steel (G4) because of the high chloride content in the formation water (the water that is pumped up from the ground with the oil/gas mixture). To optimize the service life of the mechanical seal, the seal company chose an unpressurized quench for the Panacocha solution. This involved providing an unpressurized oil quench (ISO VG32) from the atmosphere side, per API Plan 62. This is distributed on the back of the sliding surface via milled hydrodynamic oil grooves or pockets, providing a slight cooling effect. These detailed and high-precision additional measures allow the diamond-faced system to perform to its best effect.

The seal company’s consulting engineers at the place of use in Ecuador observed how the diamond-faced Panacocha seal (four of which are installed in each booster pump) works efficiently in practice. Despite operating continuously, no signs of faults in the seal have been observed. The service life should greatly exceed the guaranteed warranty period of one year. So far, the seals are running as if lubricated—even without constant liquid lubrication.