Natural Aging of Ethylene-Propylene-Diene Rubber under Actual Operation Conditions of Electrical Submersible Pump Cables

Abstract

Ethylene-propylene-diene monomer (EPDM) rubbers used in electric submersible pump (ESP) cables were analyzed after being aged in actual operation conditions in oil wellbores. These rubbers constitute the insulation and jacket layers of the ESP cables. EPDM rubbers from four different cables operating during different time intervals (2 and 4.8 years) at different depths (from 760 to 2170 m) below sea level were studied. To verify the effects of the long exposure on the rubber performance, thermal analysis was performed to determine the thermal stability and activation energy of degradation. In addition, structural analysis, through vibrational spectroscopy and crosslinking fraction assessment, was carried out. The mechanical properties of the aged rubbers were inferred through the measurement of hardness, while the absorption of a service fluid was studied by gravimetry. The results showed only minor changes in the thermal, structural, mechanical and barrier properties of the EPDM-based ESP cable layers. It is suggested that the thermo-oxidation mechanism followed by chain scission does not have a role in the degradation of EPDM within the aged ESP cables, and no sign of variation of crosslink fractions has been encountered. Therefore, it was concluded that EPDM-based layers seem not to be weak links in the configuration of modern ESP systems.

Automatic Transmission Fluids in Electrified Transmissions: Compatibility with Elastomers

“…The thermal degradation process of the EPDM is more complex, as can be seen in Figure 12. The TG curve shows a three-stage mass loss process, and the DTG curve shows the three corresponding peaks at 303, 478, and 707 • C. The first stage occurred between 236 and 360 • C and was due to the loss of volatile matter present in the composition of the elastomer [35] and it constituted the main mass degradation (31.5%). The next stage occurred over the 458-490 • C range, with a 25.52% weight reduction due to the elastomeric matrix degradation.…”

The Fatigue Wear Process of Rubber-Metal Shock Absorbers

“…Contact or immersion in aggressive liquids also affects the properties of elastomeric materials. This effect should be related to the determination of changes in the natural frequency due to changes in stiffness and damping [ 6 , 9 , 21 ]. By analyzing the work of a shock absorber in good condition ( Figure 1 ), it can be described by the commonly known equation of forced vibration with damping [ 23 ]: where —mass, —damping, —stiffness, —displacement, —force, —angular frequency, —time, P ( t ) = A sin vt —exciting force of amplitude A and frequency v .…”

“…The analysis of the used rubber and rubber-metal shock absorbers most often concerns three issues, i.e., cyclical changes in properties, reaction to large deformations and non-linearity of the stress–strain curve. In the case of materials used for shock absorbers, these parameters have been theoretically characterized and practically verified [ 7 , 8 , 9 , 10 , 11 ]. The durability of shock absorbers is of fundamental importance in shipbuilding engineering, which is mainly related to the resistance to cyclical loads and environmental impacts, primarily related to temperature and immersion in aggressive liquids [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

“…In the case of materials used for shock absorbers, these parameters have been theoretically characterized and practically verified [ 7 , 8 , 9 , 10 , 11 ]. The durability of shock absorbers is of fundamental importance in shipbuilding engineering, which is mainly related to the resistance to cyclical loads and environmental impacts, primarily related to temperature and immersion in aggressive liquids [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. According to [ 16 , 17 ] one of the most widely used techniques to predict the lifetime of polymeric materials is the use of the Arrhenius equation; however, it will not be used in this work.…”

Effects of heat and gamma radiation on the degradation behaviour of fluoroelastomer in a simulated severe accident environment

“…where K is the Boltzmann constant (8.62*10 À5 eV/K), b is assumed as 0.457, b is the heat rate (K/min), and T is the 5% weight loss temperature (K). The 5% weight loss temperature was measured at various heating rates (5,10,15, and 20 C/min), and the E a of the fluoroelastomer was calculated to 1.09 eV. Accelerated thermal aging was conducted at 140 C for 176.10 h to simulate the operation conditions of the fluoroelastomer seal in the emergency reactor depressurization valve (ERDV) at 54.4 C for 60 years.…”