The design of an experimental set up for the testing and characterization of mechanical face seals

Abstract

This thesis was centered on the design and manufacture of an experimental set up for the characterization of sintered silicon carbide mechanical face seals utilized in the oil and gas industry. The design process was focused on the ability to recreate operation conditions encountered by MFS in the oil and gas industry. The objectives for the research were established through discussion with the project sponsor. The requirements established for the project were the ability to control operation parameters such as: rotational speed of the seal, internal pressure differential, and oil temperature, as well as to record these operational parameters. An iterative design process was followed to develop a design of the experimental set up. During this process, the different components and their requirements were identified based on the objectives established along with the project sponsor. The different inputs, functions, and outputs of the experimental set up were defined through the embodiment design. This embodiment design was used in the selection and manufacture of different components and subsystems. The design and manufacture of the experimental set up was divided in different subsystems that were integrated. The subsystems include: driving system, which was designed to drive the rotor in the seal assembly. Similarly, a volume measurement system was designed and manufactured to monitor the volume of oil contained by the MFS tested and calculate the leakage through the sealing interface as well as to apply and monitor pressure to the contained fluid. A heating system was built to control the operating temperature of the seal. An oil circulation loop was designed to introduce abrasive particles to the test housing. These systems were integrated under a data acquisition system and a control panel developed using LabView software and National Instruments components. The integration of the subsystems under this platform allowed for the automation of the testing process and enabled long duration tests. A series of experiments were carried out during the commissioning of the system. These tests proved the ability of the experimental set up to maintain test constant parameters for a duration of 300 hours. Similarly, the ability of the experimental set up to operate under extreme environmental conditions and with atypical components was proved during the testing process. Optical fluorescent microscopy and confocal laser scanning microscopy were used to analyze two of the tested face seals: one exposed to normal operating conditions, and one in which abrasive particles were introduced to the sealing interface. This analysis allowed to identify a concentration of material erosion towards the inner radius of the sealing profile. Furthermore, microscopic analysis revealed the formation of concentric groves formed by the accumulation of abrasive particles on the sealing interface during the contaminant testing carried out.