Sealing Capability Research Articles

Performance characteristics of viscoseals in laminar and turbulent flow regimes

In this paper, a numerical study of a viscoseal operating behavior, under laminar and turbulent regime, is presented. The finite element method is used under different hydrodynamic regimes associated to lubrication assumptions. The theoretical model, based on the classical Reynolds equation uses the approach of average value of turbulent coefficient. In order to include the film rupture and reformation, the Reynolds equation is modified using a mass conservative algorithm. A transition zone between laminar and turbulent flow is modelled.A comparison is done between numerical and experimental results on different seals geometries and the overall comparisons are good. Next, the proposed model is used to predict viscoseal behaviors in terms of friction and seal capability for different operating conditions.

Sealing capability and hyperelastic behaviour of silicone biocomposites via compression test

AbstractDue to the excellent chemical flexibility and elastic properties of silicone rubber, Arenga pinnata‐silicone rubber biocomposites were introduced as a candidate for sealing applications. Its sealing properties were investigated via compressive properties between oil soaked and unsoaked specimens. Compression test based on ASTM D395 was employed to obtain the compression sets and its material constants are acquired using hyperelastic material models i. e. Neo‐Hookean and Mooney‐Rivlin models. Unsoaked specimens consist of 0 wt %, 4 wt %, 8 wt % and 16 wt % fibre content while for soaked specimens, only those with 0 wt % (lowest) and 16 wt % (highest) were prepared for comparison purposes. The results indicated that 16 wt % soaked specimens exhibit the highest compressive stress compared to both soaked and unsoaked 0 wt % specimens, while the compression sets of both 0 wt % and 16 wt % soaked specimens showed lower values compared to all unsoaked specimens. Using hyperelastic material models, the 16 wt % soaked specimens indicated higher material constants than unsoaked specimens while pure silicone showed the opposite. Thus, this study has found that the silicone biocomposites have the capability in sealing applications as its compressive stress shows superior properties especially for soaked specimens compared to pure silicone rubber.

Investigating the Water Sealing Capability of Polymer Concrete

The concrete water sealing capability improved substantially by using superabsorbent polymer as admixture in the concrete mix design. Researchers tried almost every conceivable material to be mixed in concrete to alter some of its properties. In this research, superabsorbent polymer is used as an admixture to improve its water tightness properties especially in concrete tanks, aeration basins and retaining structures. The concrete tries to seal the leak by blocking the water path by semi-solid gels. This gel is the product of the interaction of the superabsorbent polymer with water. This self-sealing property of concrete can also be used in any tank or container that holds and retains any kind of liquid. The super absorbent polymer absorbs water at a rate of 300 to 500 times its own weight, in a process transforming the polymer dry powered into gel. Mixing super absorbent polymer with concrete not only improves its water tightness capability, but also provides the concrete with internal curing moisture it needs to improve its strength. This property is very useful in cases where curing of concrete is difficult. The fresh concrete plasticity and consistency change as well. This property is yet to be further explored. Several samples have been prepared to study the effect of the superabsorbent polymer on the concrete strength and on the concrete capability to block the water flow. Concrete cubes, concrete beams and concrete tension samples were prepared to study the concrete strength of concrete mixed with superabsorbent polymer. Also concrete short cylindrical samples were prepared to study the concrete ability to block the water flow. These cylindrical samples were intentionally broken into two approximately equal pieces to create an induced crack. The artificially cracked samples are then subjected to water pressure to study the concrete ability to stop the water flow though the induced concrete crack. Two kinds of water pressure are used in this research; the constant head and the falling head. Samples of different amount of superabsorbent polymer were prepared to study the effect of the increase of the superabsorbent polymer on the concrete strength and on the concrete water tightness capability.

Evaluation of the Sealing Capability of the Internal Conical Connections of Implants with Titanium and Zirconia Abutments.

The purpose of this in vitro investigation was to evaluate the sealing capability of the conical implant-abutment interfaces under different abutment screw torque values using titanium and zirconia abutments with Morse taper designs. A total of 42 dental implants (n = 21 for titanium abutments and n = 21 for zirconia abutments) were inoculated internally with three bacteria. These assemblies were divided into four test groups (n = 10) based on screw fixation torques of 35 or 20 Ncm and placed in sterile broth; the remaining abutments were used as positive controls and torqued to 10 Ncm. Microleakage was quantified by enumerating the bacteria from the colony-forming units. An analysis of variance for the estimates of bacteria enumerated and microgaps was used with a post hoc analysis as indicated. A p-value of 0.05 was used as the level of significance. There was no statistically significant difference in microleakage among the four test groups; there were no significant effects of screw torque or abutment type on the bacteria enumerated. There was a significantly smaller mean microgap with the zirconia abutments. The results of this study indicated no statistically significant difference in the sealing capabilities between titanium and zirconia abutments, having internal conical connections, after increasing the abutment screw torque. It is important for clinicians to follow the guidelines suggested by the implant companies to avoid biomechanical complications over time.

Evaluation of the Sealing Capability of the Implant Healing Screw by Using Real Time Volatile Organic Compounds Analysis: Internal Hexagon Versus Cone Morse.

Implant sealing capability is a crucial issue in assessment of implant success and peri-implant marginal bone loss. Clinical studies demonstrated presence of viable bacteria in the internal part of functioning implants during tissue healing. For this study, a volatile organic compounds (VOCs) emission test was developed to evaluate the existing "seal" between implant and healing screw. Two kinds of implant-screw connection were compared: 1) internal hexagon; and 2) cone Morse. Fifteen patients were enrolled in the study, three males and 12 females, who required fixed prosthetic rehabilitation. A total of 37 implants was placed, 23 with a cone Morse taper internal connection and 14 with a screw-retained internal hexagon abutment. VOCs real-time measures were performed in the implant site immediately after removing the healing screw. Statistical analysis was carried out. Results showed VOCs maximum peak amplitude in cone Morse versus internal hexagon showed significant difference (P <0.001), whereas VOCs time to peak showed no significant difference (P = 0.7). Use of the new methodology for the VOCs emission test may lead to important new data for understanding how the "failed" attachment of implant components, in two-part assemblies, may contribute to implant losses. In particular, study results support the hypothesis that the microgap of the implant-screw healing junction could cause differences in bacterial penetration. VOCs emission test evaluation represents a new diagnostic tool with an effective approach to quickly analyze, in real time, sealing capability of dental implants with healing screw interfaces.

Injection risk assessment for intra‐formational seal geological model in a carbon sequestration application in Taiwan

AbstractAs a deep saline aquifer, the Tai‐hsi Foreland Basin in western Taiwan is regarded as an excellent locality to sequester the huge carbon emission from domestic coal‐fired power plants. Existing geological data show that an intra‐formational seal capability characterized by multilayered shale baffles can act as the primary or ultimate cap system. In this study, the relevant ranges of rock parameter of porosity (20∼35%) and permeability (0.0001∼1300 mD), respectively, for the storage layers (sandstone) and seals (shale) have been selected according to large amount of laboratory core test from a nearby pioneering 3000 m drilling and sampling within the southern flank of the Tai‐hsi Basin. Comprehensive geological models considering both homogeneous and heterogeneous cases, and a typical plume migration scenario under a single‐well injection were simulated under a 20‐year continuous injection (1 MtCO2 per year) followed by post‐injection monitoring up to 1000 years. Corresponding 2D maximum horizontal migration distances (MHMD) of CO2 plume in the storage reservoir were calculated with respect to a homogeneous reservoir model and its heterogeneous counterparts. In addition, the induced pressures at critical monitoring points were also evaluated and compared. As a consequence, the ubiquitous shale baffles of intra‐formational seal in a heterogeneous saline aquifers were proven to be a successful trapping mechanism controlling the migration distances of lateral and upward movement. Furthermore, safe carbon storage operation within Tai‐hsi Basin with formation depth range about 2135 to 2450 mRT can be ensured by checking statistically the calculated maximum MHMD and the induced pressure magnitude. © 2016 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Intraoral Temperature Triggered Shape-Memory Effect and Sealing Capability of A Transpolyisoprene-Based Polymer

In dentistry, pure gutta-percha (trans-1,4-polyisoprene (TPI)) is widely used as a main component of root canal filling materials. TPI has an interesting shape memory formed through cross-linking, and this characteristic is expected to be very effective for development of novel dental treatments; in particular, modification of the shape recovery temperature to the intraoral temperature (37 °C) will enhance the applicability of the shape-memory effect of TPI in root canal filling. In this study, trial test specimens consisting of varying proportions of TPI, cis-polyisoprene, zinc oxide, stearic acid, sulfur and dicumyl peroxide were prepared and the temperature dependence of their shape recovery, recovery stress and relaxation modulus were measured. Additionally, their sealing abilities were tested using glass tubing and a bovine incisor. As the ratio of cross-linking agent in the specimens increased, a decrease in recovery temperature and an increase in recovery stress and recovery speed were observed. In addition, the test specimen containing the highest concentration of cross-linking agent showed superior sealing ability under a thermal stimulus of 37 °C in both sealing ability tests.

Impact of particle properties on gas solid flow in the whole circulating fluidized bed system

The effect of particle properties on gas solid flow in the whole circulating fluidized bed (CFB) system was investigated. Two Geldart-B particles with different sizes were used and the differences in pressure balance and material balance of the whole CFB system with a loop seal were described. The results show that coarse particles have a larger transport velocity Utr to fall into the fast bed regime, which means accumulation in the riser is easier for the coarse particles at the same fluidization velocity Ur. The coarse particles also have a smaller solid saturation carrying rate Gs,max and a lower height of the acceleration region in the fast fluidization regime. Considering the pressure balance of the system, a higher pressure head should be supplied by the standpipe at the aeration tap of the loop seal under the same Gs when coarse particles are used. The pressure drop through the cyclone is lower for coarse particles under the same solid concentration at the entrance of it. In the loop seal, coarse particles need more aeration gas to reach the same Gs because of its higher minimum fluidization velocity. Coarse particles show a higher pressure drop through the weir part and a lower pressure drop through the horizontal part of the loop seal. In the standpipe, coarse particles have a lower drag coefficient and need a higher gas solid slip velocity to build up the same pressure gradient, so fine particles suffer less bypassing gas into the cyclone and have higher material seal capability. However, because of the same density of the two particles, the maximum pressure gradient built up in the standpipe is similar.

Modeling for performance degradation induced by wear of a hydraulic actuator of a hydraulic excavator

As an index of maintaining low fuel consumption, the digging force of an excavator is affected fully by the performance of the hydraulic actuators including boom cylinder, stick cylinder, and bucket cylinder. The seals are used widely in a fluid power system to prevent fluid leakage. However, wear induces changes in the diameter of the seal's cross-section area, having an effect on the sealing capability of seals. This article proposes a model for performance degradation induced by wear of a hydraulic actuator of an excavator. The model in this article describes the physical process of performance degradation of a hydraulic actuator by analyzing piston response when wear occurs. The model includes a dynamic model of a hydraulic actuator, a model of squeezing stress and deformation of a compressed elastomeric O-ring seal, a wear model of a seal, and a leak rate model. These models can be used for deducing the laws of performance degradation of a hydraulic actuator of an excavator and for predicting the useful life of a key component such as the seal. Finally, based on the established model, simulation results of a hydraulic actuator’s response are provided.

Impact of loop seal structure on gas solid flow in a CFB system

In a circulating fluidized bed (CFB) boiler, loop seal is one of the most commonly used non-mechanical valves. When the solids are conveyed horizontally from the supply chamber to the recycle chamber through the horizontal section, the length of the horizontal section will cause much flow resistance, which not only influences the fan burden but also the pressure and mass balance between the furnace and the external loop.In this paper, a new structure loop seal with a slope passage connecting the supply and recycle chambers (named N-type) is described. The flow characteristic of quartz sand (Geldart-B particles) in the new loop seal was studied by comparison with the traditional loop seal (named U-type).The experimental data show that the passage design connecting the two chambers of a loop seal has an obvious effect on the gas solid flow not only in the loop seal, but also in other components in the whole loop. For the N-type loop seal, the minimum aeration rate required for the onset of solid flow is equal to the minimum fluidization velocity of the bed materials, much less than with the U-type loop seal. The solid recycling capability of the N-type loop seal is better than of U-type one at low aeration rate, but this status will be reversed at high aeration rate. A small amount of vertical aeration into the bottom of the standpipe can further improve the solid recycling capability of the N-type loop seal, by reducing the inter-particle friction and build up a higher pressure drop gradient in the standpipe. At the same time, less air bypassing upward into the cyclone through the standpipe is found for the N-type loop seal at high level of aeration rate, while, at the same condition the U-type suffers severe gas bypassing with a fluidized state in the standpipe. At last, the pressure drop of the new type loop seal is much less than the pressure drop of the traditional one with the same solid flow rate, which provides an advantage for reducing fan power and sustaining more solids in the boiler furnace.

Numerical and Experimental Studies of Alternative Combined Magnetic Fluid and Labyrinth Seal with Large Gap

To improve the pressure capability of magnetic fluid seal with a large gap, a new type of alternative combined magnetic fluid and labyrinth sealing structure is proposed on the basis of magnetic fluid seal with the multiple magnetic sources and a usual magnetic fluid sealing structure with two permanent magnets is designed. The pressure capabilities of the alternative combined seal with lubricating oil-based magnetic fluid, kerosene-based magnetic fluid and ester-based magnetic fluid under 0.3 mm to 0.7 mm sealing gap have been investigated by experimental methods. The magnetic field intensity is calculated by numerical method and the theoretical pressure capability of the magnetic fluid seal in the alternative combined seal is obtained according to the theoretical pressure formula of the magnetic fluid seal. The obtained experimental values of the combined seal have been compared and analyzed with the theoretical values of the magnetic fluid seal in the alternative combined seal. The results indicate that the alternative combined magnetic fluid and labyrinth seal shows good performance compared with the multiple magnetic sources and when the height of the sealing gap is larger than 0.4 mm, the pressure capability of the alternative combined seal decreases with the increase of the height of the sealing gap.

Analysis of the Accumulation Conditions for Volcanic Gas Reservoirs: A Case from Deep Yingcheng Formation, Southern Part of Songliao Basin

Volcanic gas reservoir in deep Southern Songliao Basin has became source for incremental oil and reserves. Due to the low degree of exploration, study on the accumulation condition for volcanic gas reservoir is insufficient, to some extent, influencing the effectiveness of exploration. In this paper, the accumulation conditions for volcanic gas reservoir have been analyzed systematically including the source rock conditions, reservoir conditions, sealing conditions, conducting conditions and trap conditions. The study results show that large-scale coal-bearing strata in Shahezi Formation can provide sufficient gas for volcanic gas reservoir: the fracture systems in deep volcanic rocks can communicate with the earlier developed pores, fractures and caves, forming good reservoir and flow space; It contains multiple rock types with good preservation condition, the mudstone in first member of Quan Formation is better regional seal. Mudstone in third and fourth member of Denglouku Formation and Shahezi Formation are favorable local seals, with good seal capability for volcanic rocks gas accumulation in Yingcheng Formation. ontains three types of transporting pathways: permeable formation, unconformity and fault.

Effect of Ceramic Filler Particles on the Sealing Capability of a SrO-Based Glass Seal

The nano-sized YSZ and nano-sized Al2O3 powders were added to a SrO-Al2O3-B2O3-SiO2 glass system to control the effective viscosity and glass retention. Added filler particles evidently improved glass retention. YSZ/glass composites hardly devitrified after heat treating at 800 oC for 100 hours but Al2O3/glass composites easily devitrified. The devitrified phase, SrAl2Si2O8, decreased the CTE of Al2O3/glass composite to 5.6x10-6 /oC. Corrosion of Crofer22/APU was more severe due to contact with Al2O3/glass composite than with YSZ/glass composite. YSZ composite/glass showed the reliable sealing capability in long-term operation and repeated thermal cycles while the sealing of Al2O3/glass composite failed during thermal cycling. Such failure of Al2O3/glass composite was caused not only by the large thermal mismatch between Crofer22APU jig and sealing tape but also by intensifid corrosion of Crofer22APU.

Numerical and experimental study of magnetic fluid seal with large sealing gap and multiple magnetic sources

To improve the pressure capability of magnetic fluid seal with more than a 0.25 mm single edge gap, a magnetic fluid sealing structure with multiple magnetic sources which has five permanent magnets was designed. Magnetic field distributions under the pole pieces of the magnetic fluid seal with single and multiple magnetic sources were simulated by finite element method and its sealing pressure difference could be calculated according to the theoretical formula of the magnetic fluid seal. The effects of sealing gap height and magnetic source amount on the sealing capability were investigated experimentally. The theoretical and experimental results were compared, analyzed and discussed. The results demonstrated that the magnetic fluid seal with multiple magnetic sources was an effective method to improve the sealing capability for the rotary shaft with large gaps. The theoretical results agreed well with the experimental results when the height of the single edge gap was equal to 0.4 mm. However, it was found that when the height of the single edge gap was larger than 0.4 mm, the difference between the theoretical values and experimental values increased with the gap height because part of magnetic source had less or even no effect on magnetic fluid sealing capability.

The Estimation of Appropriateness for CO&lt;sub&gt;2&lt;/sub&gt; Geological Sequestration Based on Well Logging

CO2 geological sequestration is one of the most promising methods for reducing anthropogenic CO2 emission into the atmosphere. To carry out the technology, it is necessary to evaluate the formation geological condition of storage area for the security and effectiveness. The CO2 reserve capability of formation is mostly connected with reservoir physical property. The CO2 storage security is mostly connected with seal quality of cap rock. This paper takes advantage of logging data material to comprehensively evaluate the seal condition and storage capability from the cap rock condition of the supercritical fluid and the reservoir capacity. It gives an evaluation instance of the slected area.

Computational Analysis of Stress Field and Contact Pressure for Rubber Seal Based on Non-Linear Finite Element

This paper aims to research on the sealing capability of rubber seal by utlizing non-linear finite element analysis. After discussion on various types of strain energy functions of rubber like materials, material parameters of Mooney-Rivilin model are determined by curve fitting based on the stress strain curve from the uniaxial tensile experiment. Axis symmetric and isotropic finite element model is developed to analyze the stress field and contact pressue of O-ring seal and lip seal at different medium pressure. Von-mises stress distribution rule and contact stress distribution curve on contact surface are achieved. The results show that maximum Von Mises stress increase with the increases of oil pressure. The maximum contact stress appears on the middle contact zone and the maximum contact stress and contact width increases obviously with the increases of oil pressure. In the meanwhile, the maximum contact stress is greater than midum pressure which can prevent the leakage of midum and achieve the function of sealing. The research results will be a useful technique for predicting the properties of rubber seal and providing reference for engineering design.

Regional Seal as Key Controlled Elements of Petroleum Accumulation in the Rift Basin

Rift basin is an important petroleum basin type, in which about one third of oil and gas was discovered. To research on the main controlled elements of oil and gas accumulation, five typical rift basins in Europe are focused on the geological condition such as source rock, reservoir, seal, petroleum system, and accumulation with logging, hole, measured and analytical methods, and so on. The results showed the main regional seal controlled the petroleum distribution in the rift basin. Seals are defined by main regional seal, minor regional seas and local region according to thickness, distribution, lithostratigraphy. Viking Graben of North Sea has main regional seal about 3000m thick during late Jurassic and Cretaceous, about 81 percent of petroleum is in the Jurassic reservoir; Anglo-Dutch basin has main region thick seal during Triassic through Jurassic, and Permian reservoir accounted for 73 percent of basin reserves; Voring Basin has the main regional seal during Cretaceous through early Tertiary, the Jurassic reservoir has 85 percent of whole basin reserves; Northeast and Northwest Germany Basins have the evaporites as main regional seals during late Permian, and Permian reservoir accounted for more than 80 percent of basin reservoir, respectively. Rift Basin can develop reservoir like turbidite, source rock, seal in the basin dynamic opinion. Some main regional seals may develop overpressre because of quick subside and hydrocarbon generation at some conditions, it can strengthen seal capability. Oil and gas can migration to the main regional seal by normal faults caused by rifting, which can stop further migration so that they were accumulated under the main regional seal.

Application of Magnetic NBR Seal in the Centrifuge

It is easy for common skeleton rubber seal of centrifuge to wear and tear and ageing, great economic loss is made at machine downtime. A new-type magnetic NBR seal was designed in this paper, which has the advantages of small coefficient of friction, light wear and self-recovery because nano-BaO.6Fe2O3 was added in NBR, the structure was simpler but the capability of seal is stronger. In this paper, through experiment and simulation, the various parameters on the sealing ability was analyzed , at the same time the best parameters centrifuge seal were determined , the problem of centrifuge sealing was solved successfully.

Pressure dam influence on the performance of gas face seals

The introduction of grooves, micropores, and other forms of surface geometric modifications onto the mating seal plates has been performed to enhance the gas face seal performance. Reducing fluid leakage through the seal surface has been the main motivation for the development of efficient sealing technology for industrial turbomachinery. Pressure dams are generally etched on the seal inner and outer radii to improve even more the seal capability of reducing the gas leakage to atmosphere. This paper presents a finite element analysis carried out to determine the opening force, the flow leakage and the dynamic force coefficients of flat gas face seals with pressure dams operating under stringent conditions. Several curves of steady-state and dynamic seal performance characteristics depict the influence of the pressure dam position and width on the seal performance and efficiency.

Design and Calculation of Magnetic Liquid Seal with Rectangular Pole Teeth

The principle of magnetic liquid seal with rectangular pole teeth structure is discussed in this paper, and the magnetic circuit design process of magnetic liquid seal with rectangular pole teeth structure is systematically discussed. Using the formula of pressure capability of magnetic liquid seal with rectangular pole teeth structure and equivalent magnetic circuit, the magnetic circuit of magnetic liquid seal with rectangular pole teeth structure was designed and calculated in detail according to the kirchhoff's law of the magnetic circuit. The design method of magnetic circuit in magnetic liquid seal with rectangular pole teeth structure proposed in this paper has important reference value to the design of magnetic liquid sealing device.