Analysis of O-Ring Seal Failure under Static Conditions and Determination of End-of-Lifetime Criterion

Kömmling, Anja; Jaunich, Matthias; Pourmand, Payam; Wolff, Dietmar; Hedenqvist, Mikael S.

doi:10.3390/polym11081251

Cited by 34 publications

(48 citation statements)

References 31 publications

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“…They operate in different conditions, including scarce lubrication or even the lack of it. From the point of view of their reliability, properties of the material from which they are made are of vital significance [2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Tribological Characteristic of a Ring Seal with Graphite Filler

Szczypiński-Sala

Lubas

2020

Materials

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This paper presents the outcome of the measurement of the tribological characteristic of O-ring seals in the event of operating in conditions with a lack of lubrication. The measurement was carried out on a seal and rod model. The measurement was carried out during the condition of the round cross-section seal sliding on the surface of the piston rod. We analyzed how the friction force during rod movement, which resulted from the cooperation of the sliding nod and the rod, was changing. The experiment was conducted for various rubber materials. The aim of the research was to evaluate the friction reducing capability of graphite in rubbers of commercial sealing parts. Typical materials used for the seal and the materials, which contained the filler in the form of graphite powder, were compared. Synthetic graphite powder with a particle size of 1-2 µm was applied, and nitrile rubber (NBR) and fluoroelastomer (FKM) were compared as typical materials for O-ring seals. In the case of the two tested materials, the addition of graphite powder had an influence on the decrease in the friction force. , depending on the type and structure of the filler, the character of material wear changes [22].Research is conducted with the aim of creating materials with better functional characteristics. A lot of various kinds of fillers are studied. The developed new materials find application in various spheres of the industry. The fillers can have different forms. Although, based on the analysis in the literature, one can infer that, in general, carbon-based materials are widely applied as fillers. The fillers introduced into rubber can significantly improve many properties of the material. Even at a relatively low quantity of the applied filler, the mechanical, thermal, and electrical properties of the elastomeric matrix can be improved. Depending on the choice of the type of filler, properties such as tensile strength, elongation at break, and thermal oxidative stability can be improved. They also enable the change of properties such as the friction coefficient and specific wear rate in the case of materials used as the elements, which need to perform relative movement. Various kinds of rubber such as isobutylene-co-isoprene (IIR), polychloroprene (CR) [23], silicone rubber (SR) [24][25][26][27], ethylene-propylene-diene rubber (EPDM) [28,29], petroleum resin, and nitrile rubber (NBR) [30][31][32] are used as a matrix material. In the literature, one can come across broadly discussed research results on the application of carbon-based materials as filler [33][34][35][36].Scientists are also interested in the methods of material optimization, including reinforcement application. The identification and description of the complex structures obtained in this way is a complicated issue [37,38].The research associated with O-ring seals, described in the literature, refers to their reliability. The mechanical behavior of chosen materials, taking into account both static and dynamic strain [38][39][40], is checked during the tests. The inf...

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Section: Introductionmentioning

confidence: 99%

Tribological Characteristic of a Ring Seal with Graphite Filler

Szczypiński-Sala

Lubas

2020

Materials

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“…But it is valid only when the degradative ageing of the material is homogeneous, i.e., free of DLO effects [ 13 ]. Previously, intender modulus measurements were carried out on the surface layers of aged EPDM O-ring surfaces in uncompressed as well as in compressed state by 25%, with the same material compound and geometry [ 16 , 34 , 36 , 48 ]. The samples aged at 150 °C age homogeneously until 101 days (which corresponds to R c = 0.06 from the experimental results, see Figure 1 ); as for these samples, no heterogeneous hardening was observed [ 16 , 34 ].…”

Section: Resultsmentioning

confidence: 99%

Erroneous or Arrhenius: A Degradation Rate-Based Model for EPDM during Homogeneous Ageing

et al. 2020

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To improve the predictive capability of long-term stress relaxation of elastomers during thermo-oxidative ageing, a method to separate reversible and irreversible processes was adopted. The separation is performed through the analysis of compression set after tempering. On the basis of this separation, a numerical model for long-term stress relaxation during homogeneous ageing is proposed. The model consists of an additive contribution of physical and chemical relaxation. Computer simulations of compression stress relaxation were performed for long ageing times and the results were validated with the Arrhenius treatment, the kinetic study and the time-temperature superposition technique based on experimental data. For chemical relaxation, two decay functions are introduced each with an activation energy and a degradative process. The first process with the lower activation energy dominates at lower ageing times, while the second one with the higher activation energy at longer ageing times. A degradation-rate based model for the evolution of each process and its contribution to the total system during homogeneous ageing is proposed. The main advantage of the model is the possibility to quickly validate the interpolation at lower temperatures within the range of slower chemical processes without forcing a straight-line extrapolation.

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“…Lifetime prediction of elastomer components is a very challenging task due to different factors. Determining a suitable and reliable end-of-lifetime criterion for O-ring seals is an important issue for long-term seal applications [ 21 ]. Ageing is a term used in many branches of polymer science and engineering when the properties of the polymer change over a period of time [ 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

Reliability Prediction of Acrylonitrile O-Ring for Nuclear Power Applications Based on Shore Hardness Measurements

et al. 2021

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The degradation of polymeric components is of considerable interest to the nuclear industry and its regulatory bodies. The objective of this work was the development of a methodology to determine the useful life—based on the storage temperature—of acrylonitrile O-rings used as mechanical sealing elements to prevent leakages in nuclear equipment. To this aim, a reliability-based approach that allows prediction of the use-suitability of different storage scenarios (that involve different storage times and temperatures) considering the further required in-service performance, is presented. Thus, experimental measurements of Shore A hardness have been correlated with storage variables (temperature and storage time). The storage (and its associated hardening) was proved to have a direct effect on in-service durability, reducing this by up to 60.40%. Based on this model, the in-service performance was predicted; after the first three years of operation the increase in probability of failure (POF) was practically insignificant. Nevertheless, from this point on, and especially, from 5 years of operation, the POF increased from 10% to 20% at approximately 6 years (for new and stored). From the study, it was verified that for any of the analysis scenarios, the limit established criterion was above that of the storage time premise considered in usual nuclear industry practices. The novelty of this work is that from a non-destructive test, like a Shore A hardness measurement, the useful life and reliability of O-rings can be estimated and be, accordingly, a decision tool that allows for improvement in the management of maintenance of safety-related equipment. Finally, it was proved that the storage strategies of our nuclear power plants are successful, perfectly meeting the expectations of suitability and functionality of the components when they are installed after storage.

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Analysis of O-Ring Seal Failure under Static Conditions and Determination of End-of-Lifetime Criterion

Cited by 34 publications

References 31 publications

Tribological Characteristic of a Ring Seal with Graphite Filler

Tribological Characteristic of a Ring Seal with Graphite Filler

Erroneous or Arrhenius: A Degradation Rate-Based Model for EPDM during Homogeneous Ageing

Reliability Prediction of Acrylonitrile O-Ring for Nuclear Power Applications Based on Shore Hardness Measurements

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