Seal Effectiveness Research Articles

Study on Welding Techniques of 316L Lined Bimetallic Pipe

It is well known that welding technique was often a knotty problem for bimetallic lined steel pipes to use widely. A number of failures in secession of weld cracking and weld corrosion had been observed in oil fields in recent years, which seriously disrupted the order of oil and gas production. To solve welding problems of 316L bimetallic lined pipes, works outcome about failure analysis and welding process research were presented in this paper. Failure analysis results confirmed that Welding defects, high hardness regions was the main reasons about failure problems of weld crack while structure design defects of seal weld and bad back-protection effects of flux-cored wire resulted in weld corrosion. Welding defects in the regions of seal weld became the failure source while the high hardness both in the region of seal weld and weld joint formed the crack propagation channel, and therefore both initially contributed to weld cracking. Additionally owing to the structure design of seal weld, liner layer would be heated over and over again during the period of seal weld and then it was not enough to protect CRA layers from being damaged during the period of girth weld. As a result the corrosion resistance in the welding area was reduced to become a weak area. On the basis of failure analysis, further research work was carried out to improve welding performance. Seal weld structure and girth weld process was improved. The difference of welding wires and welding process was analyzed, and their defects were described separately. Results showed that the welding performance welding by ERNiCrMo-3 and supporting technology was more reliable than ATS-F309L and supporting technology, whether seal weld or butt welding. The distribution and value of the hardness could be effectively controlled; Moreover, corrosion resistance performance was also better. Therefore, the seal weld and girth weld conducted by ERNiCrMo-3 and supporting technology was feasible.

Car Soundproof Improvement through an SMA Adaptive System

The work at hand focuses on an adaptive system aimed at improving the soundproof performance of car door seals at specific regimes (cruise), without interfering with the conventional opening and closing operations. The idea addresses the necessity of increasing seal effectiveness, jeopardized by aerodynamic actions that strengthen as the speed increases, generating a growing pressure difference between the internal and the external field in the direction of opening the door, and then deteriorating the acoustic insulation. An original expansion mechanism driven by a shape memory alloy (SMA) wire was integrated within the seal cavity to reduce that effect. The smart material was activated (heated) by using the Joule effect; its compactness contributed to the realization of a highly-integrable and modular system (expanding cells). In this paper, the system development process is described together with the verification and validation activity, aimed at proving the functionality of the realized device. Starting from industrial requirements, a suitable solution was identified by considering the basic phenomenon principle and the allowable design parameters. The envisaged system was designed and its executive digital mock-up (CAD, computer-aided design) was released. Prototyping and laboratory tests showed the reliability of the developed numerical models and validated the associated predictions. Finally, the system was integrated within the reference car. To demonstrate the insulation effect, the experimental campaign was carried out in an anechoic room, achieving significant results on the concept value.

Research on a kind of self-compensation variable-clearance sealing hydraulic cylinder with a thin shell structure

Hydraulic cylinder is the most typical hydraulic actuator. The traditional sealing ring used in hydraulic cylinder produces the friction which greatly affects the high speed performance of the hydraulic cylinder. Researchers tried to improve the situation by improving sealing material and structure. But the problem between friction and leakage is not solved radically. Then a kind of high speed hydraulic cylinder with low friction was developed. The constant clearance seal technology was employed in this hydraulic cylinder. This hydraulic cylinder with constant clearance seal has the characteristics of low friction and fast speed. However, the internal leakage always exists, and the hydraulic cylinder volume efficiency is obviously decreased with the working pressure increasing. There is a contradiction between the sealing performance and working pressure in the hydraulic cylinder. To solve the above problems, we propose a kind of self-compensation variable-clearance sealing hydraulic cylinder. The compensation mechanism, compensation effect and adaptability of variable clearance seal are studied. The load analysis model of the piston lip in flow field is established. These provide theoretical basis and technical support for design and manufacture. Then the optimization method of the piston structure of variable clearance hydraulic cylinder is studied. Three different types of piston structures are proposed. And the piston structure with the best sealing effect is determined by the comparison of the study. The test platform is developed. Measure methods are adopted to measure the static and dynamic internal leakage respectively. The validity of the theoretical research is verified through tests.

NEW APPROACH TO STRESS RESEARCH IN PHOCIDS-POTENTIAL OF DEHYDROEPIANDROSTERONE AND CORTISOL/DEHYDROEPIANDROSTERONE RATIO AS MARKERS FOR STRESS IN HARBOR SEALS ( PHOCA VITULINA) AND GRAY SEALS ( HALICHOERUS GRYPUS).

Cortisol is known to reflect the level of the stress response. However, measuring the cortisol concentration only once fails to provide sufficient information about the duration of the stress exposure. Moreover, handling is an acute stressor and increases cortisol secretion especially in wildlife species. Yet, in phocids reliable indicators are missing that reflect potential chronic effects of stress. The adrenal-derived steroid hormone dehydroepiandrosterone (DHEA) has been described as biomarker for the assessment of the stress status but has not been applied to marine mammal stress research. Therefore, DHEA, the sulfated precursor DHEAS and the cortisol/DHEA ratio were determined in serum of different seals. One group consisted of harbor ( Phoca vitulina) and gray seals ( Halichoerus grypus) that were habituated to human handling. The other two groups included healthy and free-ranging seals suffering from a disease. Blood samples were taken from 11 habituated (six males, five females), 17 wild_healthy (13 males, four females), and nine wild_diseased seals (four males, five females). No differences in serum cortisol levels could be detected between wild_healthy and wild_diseased seals. On the contrary, wild_diseased seals showed the lowest DHEA concentration compared to the other two groups. Wild_diseased seals also revealed the highest cortisol/DHEA ratio compared to the habituated_zoo (2,074.7 ± 351.4 vs. 121.5 ± 26.8, P < 0.001) and wild_healthy seals (827.9 ± 214.3, P < 0.01). DHEA and the cortisol/DHEA ratio may reflect differences in the functionality of the hypothalamic-pituitary-adrenal axis and therefore represent valuable tools for the assessment of stress-related effects in seals.

Model of Effect of Hot Gas Ingress on Temperatures of Turbine Disks

Ingress is the leakage of hot mainstream gas through the rim-seal clearance into the wheel-space between the rotating turbine disk (the rotor) and the adjacent stationary casing (the stator). The high-pressure rotor is purged by a radial outflow of air from the high-pressure compressor, and this cooling air is also used to reduce the ingress. The engine designer needs to predict the stator and rotor temperatures as a function of cooling-flow rate. The sealing effectiveness determines how much air is needed to reduce or prevent ingress; although there are numerous theoretical and experimental papers on the effectiveness of different seal geometries, there are few papers on the effect of ingress on the temperature of the rotating disk. This is an unsolved problem of great practical importance: under high stress, a small increase in metal temperature can significantly reduce operating life. In this paper, conservation equations and control volumes are used to develop theoretical equations for the exchange of mass, concentration and enthalpy in an adiabatic rotor–stator system when ingress occurs. It is assumed that there are boundary layers on the rotor and stator, separated by an inviscid rotating core, and the fluid entrained from the core into the boundary layer on the rotor is recirculated into that on the stator. The superposed cooling flow protects the rotor surface from the adverse effects of hot-gas ingress, which increases the temperature of the fluid entrained into the rotor boundary layer. A theoretical model has been developed to predict the relationship between the sealing effectiveness on the stator and the adiabatic effectiveness on the rotor, including the effects of both ingress and frictional heating. The model involves the use of a nondimensional buffer parameter, Ψ, which is related to the relative amount of fluid entrained into the rotor boundary layer. The analysis shows that the cooling flow acts as a buffer, which attenuates the effect of hot gas ingress on the rotor, but frictional heating reduces the buffer effect. The theoretical effectiveness curves are in good agreement with experimental data obtained from a rotor–stator heat-transfer rig, and the results confirm that the buffer effect increases as the sealing effectiveness of the rim seals decreases. The analysis quantifies the increase in the adiabatic rotor temperature due to direct frictional heating, which is separate from the increase due to the combined effects of the ingress and the indirect frictional heating of the entrained fluid. These combined effects are reduced as Ψ increases, and Ψ = 1 at a critical flow rate above which there is no entrained fluid and consequently no indirect heating of the rotor. The model also challenges the conventional physical interpretation of ingress as, in general, not all the hot gas that enters the rim-seal clearance can penetrate into the wheel-space. The ingress manifests itself through a mixing of enthalpy, which can be exchanged even if no ingested fluid enters the wheel-space.

Effect of Hydrothermal Sealing on Wettability and Electrochemical Behavior of TMPSi Treated Anodized Aluminum

Sol–gel derived films can be deposited on metals to improve their corrosion resistance. Anodization pretreatment process is commonly used to enhance the corrosion protection of the aluminum alloys. In this work, the substrate was first anodized and sealed hydrothermally, then dipped into the trimethoxypropylsilane (TMPSi) sol as a precursor. The films made of TMPSi sol were examined for their corrosion inhibition properties and hydrophobicity. The surface characterization of the samples was evaluated with X-ray diffraction, field emission scanning electron microscope (FESEM), scanning electron microscopy, surface roughness measurement and static contact angle measurements. The effect of hydrothermal sealing before silane treatment on the hydrophobicity of surface was studied by static contact angle measurements. In order to evaluate the corrosion resistance of the samples, open circuit potential measurements and electrochemical impedance spectroscopy (EIS) were used. FESEM results showed that hydrothermal sealing increases the homogeneity of the surface morphology and thus corrosion resistance increases compared to the silane treated anodized surface. Surface roughness of that hydrothermal sealing sample before silane treatment increased surface roughness and hydrophobicity. Hydrothermal sealing before silane treatment tends to result in a more compact surface that prevents the contact of corrosive materials with porous structure. The electrochemical behavior of the samples was evaluated by EIS using 3.5% NaCl solution. According to the EIS results, samples, which were hydrothermally sealed in water and then coated by a TMPSi sol, showed highest corrosion resistance.

Dynamic analysis of a planar multi-stage centrifugal pump rotor system based on a novel coupled model

The coupled rotor-dynamics issue is always one of the most important and difficult research for multi-stage pump system due to the complexity of multiple fluid-induced forces and multi-degree of freedom rotor model. In this paper, the Reynolds equation of journal bearing is solved by the finite difference method and corresponding fluid-induced force is obtained by small parameter method. In addition, the dynamic coefficients of annular seal are calculated according to bulk-flow model and perturbation method. Furthermore, a novel rotor system model fully considering the coupled effects of bearing and seal is proposed by matrix manipulation method. Then the coupled rotor-dynamics for multi-stage pump system is investigated subsequently based on the novel model. Finally, the Lomakin effect of annular seal is studied in detail. The calculated results indicate that the fluid-induced force of seal exerting on the rotor system should not be ignored in the calculation of coupled dynamic characteristics. Smaller length and clearance of annular seal are good for the stability of coupled rotor system. Compared with asymmetric structure, the symmetric sealing structure has a larger stability margin on condition of ‘rigid rotor’ status. Moreover, the Lomakin effect on stability presents linear superposition property. The proposed method can provide valuable reference for the design and modeling of multi-dimensional matrix system.

Thermo-mechanical characterization of carbon fiber reinforced silicon carbide composites having boron nitride as an interphase material

The carbon fiber reinforced silicon carbide composites were prepared by an isothermal chemical vapour infiltration process. In order to achieve the required density, the carbon fiber preforms in the form of rectangular panels were infiltrated by silicon carbide (SiC) matrix. Prior to the matrix infiltration, a thin coating of boron nitride, as an interphase, was applied on the fiber preform. The test samples were subjected to seal coating of silicon carbide by chemical vapour deposition process. The effect of protective SiC seal coating was examined by testing (3-point bend test) the uncoated and the seal coated samples at different temperatures. Higher value of the flexural strength was observed for the seal coated samples as compared to the uncoated samples, when got tested at high temperature (up to 1400 °C). The detailed analysis of the fractured surfaces of the tested samples was carried out.

Effects of Purge Flow Configuration on Sealing Effectiveness in a Rotor–Stator Cavity

Secondary air is bled from the compressor in a gas turbine engine to cool turbine components and seal the cavities between stages. Unsealed cavities can lead to hot gas ingestion, which can degrade critical components or, in extreme cases, can be catastrophic to engines. For this study, a 1.5 stage turbine with an engine-realistic rim seal was operated at an engine-relevant axial Reynolds number, rotational Reynolds number, and Mach number. Purge flow was introduced into the interstage cavity through distinct purge holes for two different configurations. This paper compares the two configurations over a range of purge flow rates. Sealing effectiveness measurements, deduced from the use of CO2 as a flow tracer, indicated that the sealing characteristics were improved by increasing the number of uniformly distributed purge holes and improved by increasing levels of purge flow. For the larger number of purge holes, a fully sealed cavity was possible, while for the smaller number of purge holes, a fully sealed cavity was not possible. For this representative cavity model, sealing effectiveness measurements were compared with a well-accepted orifice model derived from simplified cavity models. Sealing effectiveness levels at some locations within the cavity were well-predicted by the orifice model, but due to the complexity of the realistic rim seal and the purge flow delivery, the effectiveness levels at other locations were not well-predicted.

Stability Analysis of Connecting-tunnel Sealing Plug in Underground Storage Cavern

Connecting tunnel sealing plug is one of the important structures in water sealed cavern. The plugs ensures the safety of main cavern and water seal effect. This paper uses the finite element software doing several calculation steps including geometry model, underground stress distribution, boundary condition and assumption, to analysis the connecting plugs and rock mass’ stability. On the basis of no-relative-slip assumption, it can reach the conclusion that the sealing plugs and rock mass are in safety conditions. Thus to make sure close and tight relation between plugs and rock mass, a variety of grouting measures are promoted and fulfilled.

Chip seal aggregate evaluation and successful roads preservation

The Federal Highway Administration’s Every Day Counts (EDC) initiative focuses on saving time, resources and money. EDC has brought infrastructure preservation to the forefront of many conversations. Chip seals are a cost-effective pavement preservation strategy, and continued studies verifying their performance benefits continue to be in high demand as agencies struggle to fund preservation programs. This study documents the effectiveness of chip seals when good materials, good construction and good agency oversight work together. Chips seals extend the service life of pavements an average of 5–6 years. This study gathers two years of field performance data (June 2014–June 2016) from chip seal projects constructed in Oregon. The data includes laboratory and field-testing to assess chip seal materials used in construction and tracks the performance of the chip seal pavements, both emulsified asphalts and hot-applied asphalts. Findings show that chip seals constructed with good quality materials enhance the surface texture properties and reduce the appearance of distresses over the two-year monitoring period for most sections.

Research on the effect of wall corrosion and rim seal on the withdrawal loss for a floating roof tank.

Storage tanks are important parts of volatile organic compound (VOC) fugitive emission sources of the petrochemical industry; the floating roof tank is the main oil storage facility at present. Based on the mechanism of withdrawal loss and the type of rim seal, octane and gasoline were taken as the research objects. A model instrument for simulating the oil loading process by the 316 stainless steel and A3 carbon steel as the test piece was designed, and the film thickness was measured by wet film thickness gauge to investigate the influence of the corrosion of the tank wall and rim seal on the withdrawal loss for floating roof tanks. It was found that withdrawal loss was directly proportional to the shell factor, and the oil thickness of the octane and gasoline increased with the strength of the wall corrosion with the same wall material and rim seal. Compared with the untreated test piece, the oil film thickness of the octane/gasoline was increased by 7.04~8.57μm/13.14~21.93μm and 5.59~11.49μm/11.61~25.48μm under the corrosion of hydrochloric acid for 32 and 75h, respectively. The oil film thickness of octane and gasoline decreased with the increasing of the rim seal, and the oil film thickness of the octane decreased by 11.97~28.90% and 37.32~73.83% under the resilient-filled seal and the double seal, respectively. The gasoline dropped by 11.97~31.18% and 45.98~75.34% under the resilient-filled seal and the double seal, respectively. In addition, the tank surface roughness reduced the compression of the rim seal on the tank wall, and the effect of scraping decreased. The API withdrawal loss formula for a floating roof tank was recommended to take into account the effect of the rim seal to improve the accuracy of the loss evaluation. Finally, some measures of reducing the withdrawal loss were proposed.

Performance of radial–axial clearance rim seal in realistic working conditions

Performance of radial–axial clearance rim seal (RACS) in realistic working condition is investigated and compared with axial-clearance rim seal (ACS), radial-clearance rim seal (RCS) in this paper. Authors use the numerical method of conjugate heat transfer for calculation to accurately take heat transfer between the rotor–stator cavity flow and the solid discs into account. Results show that seal effectiveness and cooling effectiveness of RACS are the best when compared with ACS and RCS, the minimum mass flow rate for seal of RACS is 75% of that of RCS, and 34.6% of ACS.RACS has higher air-cooled aerodynamic efficiency, minimizing the mainstream performance penalty when compared with ACS and RCS. Corresponding to the respective minimum mass flow rate for seal, the air-cooled aerodynamic efficiency of RACS is 23.71% higher than that of ACS, and 12.79% higher than the RCS. Finite element analysis in turbine disc shows that RACS minimizes the flow rate of cooling air required for suppressing the radial growth of turbine disc in the three rim seal types. Mass flow rate of the required cooling air of RACS is approximately 40.9–52.9% of that of ACS, and 70–75% of RCS.

Pliocene Deep Water Channel System of Celebes Molasse as New Exploration Play In Banggai Sula Foreland Basin, Eastern Sulawesi-Indonesia

Banggai-Sula foreland basin in Matindok block is the product of Late Miocene to Early Pliocene collision between Banggai-Sula microcontinent and East Sulawesi Ophiolite (ESO)-magmatic arc of Sundaland. Proven petroleum system plays for Donggi, Senoro, and Matindok gas fields are Miocene build-up carbonate and platform carbonates related to wrench structures, sealed by Plio-Pleistocene Celebes Molasse consists of conglomerate, conglomeratic sandstone, shale and charged during early Pliocene related to collisional tectonic from Miocene marine clastic source rocks. Latest interpretation of 3D & 2D seismic datasets on onshore area of Matindok block shown that there is possibility of NE to SW trending channel systems existed in Plio-Pleistocene Celebes Molasse as post collision sediments. Based on biostratigraphy interpretation, Celebes Molasse interval was deposited in marine environment, generally outer sublittoral to upper bathyal. Channel filled pattern on seismic data expression shown onlap, divergent and mounded-onlap fills on 6 (six) interpreted channel bodies. Fining upward sequences is well recognized based on gamma ray log from several wells that penetrated those interpreted channel. The thicknesses of channel bodies vary from 50 m to 150 m with sand to shale ratio up to 40 % and gas composition reading from C1 to C3. Despite of there is no well testing data on these channels interval; we believed that this Pliocene deep water channel can become the new exploration play although several studies about seal effectiveness of channel bodies as stratigraphic traps, lateral and vertical migration pathways need to be carried out.

Margin of Safety Estimation of Tongue and Groove Joint of Rocket Motors with Discontinuous End Ring

Rocket motors are used worldwide in both upper and booster stages.Solid rockets can provide high thrust for relatively low cost. Considering the large size of solid motors, these motors are to be designed as segmented motor cases. Segmented motor cases have to be joined by segment joint. Segment joint with tongue and groove configuration provides performance reliability in effective sealing of joints. A tongue-and-groove arrangement employs a pressure-energized metal seal which expands radially when the cylinders are internally pressurized. The radial expansion enhances the sealing effect of the metal seal between the tongue and the groove. Metal end rings welded to the shell motor cases and shear pins for the final assembly provides the sealing. The load sharing among the pins depends on the presence of the slit in a ring, whole &amp; pin dimensional clearances, internal pressure and friction between the metal end rings. Structural analysis of a discontinuous metallic segment ring and shear pins iscarried out in this study. Structural analysis is based on detailed solid model for the segment joint. The load augmentation in the shear pin near the discontinuity is worked out based on a load augmentation factor derived out of FE analysis. The study further extended to a deviation in a nearby hole / pin combination at the vicinity of the discontinuity and is presented in this paper.

Effect of a robotic seal on the motor activity and sleep patterns of older people with dementia, as measured by wearable technology: A cluster-randomised controlled trial

ObjectivesThe robotic seal, PARO, has been used as an alternative to animal-assisted therapies with residents with dementia in long-term care, yet understanding of its efficacy is limited by a paucity of research. We explored the effects of PARO on motor activity and sleep patterns, as measured by a wearable triaxial accelerometer. Study designCluster-randomised controlled trial, involving 28 facilities in Queensland, Australia. Nine facilities were randomised to the PARO group (individual, non-facilitated, 15-min sessions three afternoons per week for 10 weeks), 10 to a plush toy (PARO with robotic features disabled) and nine to usual care. Main outcome measuresChanges in day- and nighttime motor activity and sleep after the 10-week intervention, as measured by SenseWear® armbands, worn by participants continuously for 24 h at baseline, during two single intervention days in weeks 5 and 10 respectively, and post-intervention (week 15). Analyses followed intention-to-treat, using repeated-measures mixed-effects models. ResultsAfter 10 weeks, the PARO group showed a greater reduction in daytime step count than usual care (p = 0.023), and in nighttime step count (p = 0.028) and daytime physical activity (p = 0.026) compared with the plush toy group. At post-intervention, the PARO group showed a greater reduction in daytime step count than the plush toy group (p = 0.028), and at nighttime compared with both the plush toy group (p = 0.019) and the usual-care group (p = 0.046). The PARO group also had a greater reduction in nighttime physical activity than the usual-care group (p = 0.015). ConclusionsPARO may have some effect on motor activity of older people with dementia in long-term care, but not on sleep patterns.Australian New Zealand Clinical Trials Registry (ACTRN12614000508673).

Structural, mechanical and tribocorrosion behaviour in artificial seawater of CrN/AlN nano-multilayer coatings on F690 steel substrates

Abstract The CrN monolayer and CrN/AlN nano-multilayer coating were successfully fabricated by reactive magnetron sputtering on F690 steel. The results show that CrN monolayer exhibits a face centered cubic crystalline structure with (111) preferred orientation and CrN/AlN nano-multilayer coating has a (200) preferred orientation. This design of the nano-multilayer can interrupt the continuous growth of columnar crystals making the coating denser. The CrN/AlN nano-multilayer coating has a better wear resistance and corrosion resistance compared with the CrN monolayer coating. The tribocorrosion tests reveal that the evolution of potential and current density of F690 steel and CrN monolayer or CrN/AlN nano-multilayer coating see an opposite trend under the simultaneous action of wear and corrosion, which is attributed to that F690 steel is a non-passive material and PVD coatings is a passive material. The nano-multilayer structure has a good “Pore Sealing Effect”, and the corrosive solution is difficult to pass through the coating to corrode the substrate.

The (in)effectiveness of green seals on consumer behavior: a experimental study [doi: 10.21529/RECADM.2017003

The (in)effectiveness of green seals on consumer behavior: a experimental study [doi: 10.21529/RECADM.2017003

Performance evaluation of trapezoidal teeth labyrinth seal

The present paper investigates the effects of the trapezoidal teeth labyrinth seal on the leakage amount in gas turbines. The influences of increasing the number of teeth from 1 to 6 with step 1 and the tip clearance s=0.5 to 7.5 mm on the leakage flow at different pressure ratios of PR=1.5, 2 and 2.5 are examined, comprehensively. The analysis is performed numerically using a Finite-Volume software with the k-e turbulent model. The obtained results show a good agreement in comparison with the other research results. The results show that an increase in the number of teeth causes a decrease in the leakage flow. An increase in the tip clearance (s) from 0.5 mm to around 7.5 mm leads to a decrease in the leakage flow, like the step labyrinth behavior, while an increase beyond 7.5 mm results into a leakage increase, the behavior of the straight labyrinth.

A Comparison of Single and Double Lip Rim Seal Geometries

The effect of the purge flow, engine-like blade pressure field, and mainstream flow coefficient are studied experimentally for a single and double lip rim seal. Compared to the single lip, the double lip seal requires less purge flow for similar levels of cavity seal effectiveness. Unlike the double lip seal, the single lip seal is sensitive to overall Reynolds number, the addition of a simulated blade pressure field, and large-scale nonuniform ingestion. In the case of both seals, unsteady pressure variations attributed to shear layer interaction between the mainstream and rim seal flows appear to be important for ingestion at off-design flow coefficients. The double lip seal has both a weaker vane pressure field in the rim seal cavity and a smaller difference in seal effectiveness across the lower lip than the single lip seal. As a result, the double lip seal is less sensitive in the rotor–stator cavity to changes in shear layer interaction and the effects of large-scale circumferentially nonuniform ingestion. However, the reduced flow rate through the double lip seal means that the outer lip has increased sensitivity to shear layer interactions. Overall, it is shown that seal performance is driven by both the vane/blade pressure field and the gradient in seal effectiveness across the inner lip. This implies that accurate representation of both, the pressure field and the mixing due to shear layer interaction, would be necessary for more reliable modeling.