Seal Pairs Research Articles

Structure Analysis and Design Improvement of Plunger Seal Pair in Fracturing Pump

The performance and service life of the plunger and seal of fracturing pumps directly affect the implementation of fracturing technology. The structure characteristics of the plunger seal pair in OPI-1800AWS fracturing pump are analyzed. This paper focus on the contact stress between the plunger and the sealing ring, and the effect of the sealing ring structure parameters on the contact stress is analyzed, and the structure of the sealing ring is optimized. The failure and leakage reason of the plunger seal pair is analyzed. A new structural renovation plan for the plunger seal pair in fracturing pumps is put forward, that is, the sealing effect and service life of the plunger and seal can be increased by strengthening the plunger surface, selecting excellent sealing materials, improving the structure of the sealing ring, adding scraping ring, keeping the moving track of the plunger and the axis of the cylinder jacket in line.

Maternal transfer of perfluoroalkyl substances in hooded seals.

The role of milk in the transfer of perfluoroalkyl substances (PFASs) to offspring is not well known in wildlife. Eight PFASs were quantified in plasma and milk in mother-pup pairs of hooded seals (Cystophora cristata) during the nursing period, and the role of milk in the transfer process was analyzed. Hooded seal was chosen because of its short lactation period (3-4 d), during which the pup feeds only on milk. Placental or lactation transfer would thus be the only source of PFAS in the pup. Of the 8 PFASs analyzed (Σ8 PFAS), 7 were found in all samples; therefore, milk is a source to PFASs in pups. Perfluorooctane sulfonate was the dominant PFAS in all samples. Mean Σ8 PFAS concentrations were 6.0 ng/g protein (36 ng/g wet wt) in maternal plasma, 0.77 ng/g protein (3.2 ng/g wet wt) in milk, and 12 ng/g protein (66 ng/g wet wt) in pup plasma. Measured concentrations in plasma were within ranges previously reported from other seal species, below known toxicity thresholds for experimental rodents. Individual PFASs differed in transfer efficiency from mother to pup, depending on carbon chain lengths, with the lowest relative transfer for the intermediate-chained PFASs (C9 -C10 ). The results show maternal transfer of PFASs via both milk and the placenta, of which placental transfer is the dominant pathway. Environ Toxicol Chem 2017;36:763-770. © 2016 SETAC.

Criterion for non-interference of solid metal seal pair in double-offset butterfly valve

To avoid leakage of the seal pair is one of the key considerations in valve designs. As to double-offset butterfly valves (DOBVs) with solid metal seal pair, it means that no interference should occur at the seal pair. By constructing a mathematical model for the sealing surface of DOBV, this paper provides a criterion for non-interference for the seal pair in DOBV. Detailed investigations show that the interference area can be influenced by the radial offset, the diameter of valve disc, the sealing thickness, and the cone angle of the sealing surface. The top and the bottom parts of the sealing surface are the areas where interference is least likely to be avoided. The axial offset can also influence the interference areas, resulting in its nonlinear changes. Moreover, the minimum radial offset for entire non-interference of the seal pair of a DOBV changes nonlinearly with the increase of the axial offset or the cone angle. The results presented in this paper may suggest a strategy for parameter optimization of DOBVs.

New insights into the petroleum prospectivity of the Browse Basin: the results of a multi-disciplinary study

The Browse Basin hosts large gas accumulations, some of which are being developed for conventional liquefied natural gas (LNG). Extensive appraisal drilling has been focused in the central Caswell Sub-basin at Ichthys and Prelude, and along the extended Brecknock-Scott Reef Trend; whereas elsewhere the basin remains underexplored. To provide a better understanding of regional hydrocarbon prospectivity, the sequence stratigraphy of the Cretaceous succession and structural framework were analysed to determine the spatial relationship of reservoir and seal pairs, and those areas of enhanced source rock development. The sequence stratigraphic interpretation is based upon a common North West Shelf stratigraphic framework that has been developed in conjunction with industry, and aligned with the international time scale. Sixty key wells and 2D and 3D seismic data have been interpreted to produce palaeogeographic maps and depositional models for the Cretaceous succession. Geochemical analyses have characterised the molecular and stable isotopic signatures of fluids and correlated them with potential source rocks. The resultant petroleum systems model provides a more detailed understanding of source rock maturity, organic richness and hydrocarbon-generation potential in the basin. The model reveals that many accumulations have a complex charge history, with the mixing of hydrocarbon fluids from multiple Mesozoic source rocks, including the Lower–Middle Jurassic J10–J20 supersequences (Plover Formation), Upper Jurassic–Lowermost Cretaceous J30–K10 supersequences (Vulcan Formation), and Lower Cretaceous K20–K30 supersequences (Echuca Shoals Formation). Burial history and hydrocarbon expulsion models, applied to these Jurassic and Cretaceous supersequences, suggest that numerous petroleum systems are effective within the basin. For example, hydrocarbons are interpreted to have been generated from several source pods within the southern Caswell Sub-basin with migration continuing onto the Yampi Shelf, an area of renewed exploration interest.

The role of seal integrity in the Vlaming Sub-basin (Perth Basin) for preservation of hydrocarbon accumulations

SUMMARY The offshore Vlaming Sub-basin, located in the southern part of the Perth Basin, is a Mesozoic depocentre estimated to contain over 12 km of sediments. It has several potential source rock intervals, good reservoir and seal pairs and an active petroleum system. The reasons for a lack of exploration success in this basin have been re-assessed by analysing fault reactivation and signs of hydrocarbon seepage. A recently completed study integrated structural mapping with analysis of fluid inclusion results. New data and interpretations show that a number of synrift faults with signs of reactivation in seismic data also have Fluid Inclusion Stratigraphy (FIS) anomalies above the regional seal. Many previously identified plays rely on the post-rift South Perth Shale for a seal. Our analysis suggests that many faults were reactivated after the deposition of the South Perth Shale, with some showing signs of present-day reactivation. Reactivated faults provided migration pathways for generated hydrocarbons; therefore, no accumulations were formed at these locations. The study provides insight into the location of leaky structures and areas with potentially valid plays in the Vlaming Sub-basin.

Experimental study on frictional characteristics of tungsten carbide versus carbon as mechanical seals under dry and eco-friendly lubrications

Lubrication reduces the friction between the interfaces of sliding surfaces in the mechanical seals that operate for extended period of time. Due to environmental issues caused by mineral oil-based lubricants, the use of organic based vegetable oils had increased worldwide due to the nontoxic and biodegradable characteristics. In this work an experimental study was carried out by employing a seal pair of tungsten carbide and resin impregnated carbon mechanical seals, its frictional behaviour was studied under the eco-friendly lubricant from the class of vegetable oils — soybean oil and canola oil with an eco-friendly solid lubricant i.e. boric acid powder. An experimental setup was designed and fabricated to study the frictional characteristics of the seal for varying normal load and constant speed. The friction characteristics was studied under unlubricated conditions, independent paraffin oil, soybean oil, canola oil lubricating modes and finally 1wt.%, 3wt.% and 5wt.% of boric acid powder mixed individually with soybean and canola oil. After all running-in test of all lubricating conditions, 5wt.% of boric acid powder mixed with soybean oil had contributed a hybrid tribofilm and resulted in the lowest friction coefficient value in the range of 0.06–0.07.

Non-Contacting Carbon Seal for High-Temperature and Large-Diameter Turbomachinery Applications

Non-contacting circumferential segmented hydrodynamic carbon seals have been used in aviation engines to seal lubrication oil from air flow path in bearing locations. Its tight clearance and long life from non-contacting operation are attractive to large gas turbine and steam turbine where efficiency is critical. In this paper, development of segmented carbon seals for large turbomachine is presented. The seal is targeting locations where temperature is over 500C (930F) and rotor diameter is over 0.38 meter (15 inches). Comparing to current circumferential segmented carbon seal technology, the new seal is capable of running 260C (480F) hotter and it is 3 times larger.Three sets of test seals were made with newly developed manufacture process. The test seals are 12 inches in diameter, made of three different carbon grades that were down-selected from a dozen candidates having potential of enduring high temperature of air and superheated steam. A test rig was set up to test one pair of seals at a time. One of the seals is facing high-temperature steam, while the other one is exposed to hot air.

Simulation of the impact of faults on CO2 injection into sandstone reservoirs

AbstractNumerical simulations of multiphase CO2 behavior within faulted sandstone reservoirs examine the impact of fractures and faults on CO2 migration in potential subsurface injection systems. In southeastern Utah, some natural CO2 reservoirs are breached and CO2‐charged water flows to the surface along permeable damage zones adjacent to faults; in other sites, faulted sandstones form barriers to flow and large CO2‐filled reservoirs result. These end‐members serve as the guides for our modeling, both at sites where nature offers ‘successful’ storage and at sites where leakage has occurred. We consider two end‐member fault types: low‐permeability faults dominated by deformation‐band networks and high‐permeability faults dominated by fracture networks in damage zones adjacent to clay‐rich gouge. Equivalent permeability (k) values for the fault zones can range from <10−14 m2 for deformation‐band‐dominated faults to >10−12 m2 for fracture‐dominated faults regardless of the permeability of unfaulted sandstone. Water–CO2 fluid‐flow simulations model the injection of CO2 into high‐k sandstone (5 × 10−13 m2) with low‐k (5 × 10−17 m2) or high‐k (5 × 10−12 m2) fault zones that correspond to deformation‐band‐ or fracture‐dominated faults, respectively. After 500 days, CO2 rises to produce an inverted cone of free and dissolved CO2 that spreads laterally away from the injection well. Free CO2 fills no more than 41% of the pore space behind the advancing CO2 front, where dissolved CO2 is at or near geochemical saturation. The low‐k fault zone exerts the greatest impact on the shape of the advancing CO2 front and restricts the bulk of the dissolved and free CO2 to the region upstream of the fault barrier. In the high‐k aquifer, the high‐k fault zone exerts a small influence on the shape of the advancing CO2 front. We also model stacked reservoir seal pairs, and the fracture‐dominated fault acts as a vertical bypass, allowing upward movement of CO2 into overlying strata. High‐permeability fault zones are important pathways for CO2 to bypass unfaulted sandstone, which leads to reduce sequestration efficiency. Aquifer compartmentalization by low‐permeability fault barriers leads to improved storativity because the barriers restrict lateral CO2 migration and maximize the volume and pressure of CO2 that might be emplaced in each fault‐bound compartment. As much as a 3.5‐MPa pressure increase may develop in the injected reservoir in this model domain, which under certain conditions may lead to pressures close to the fracture pressure of the top seal.

Changes in trace elements during lactation in a marine top predator, the grey seal

Lactation in pinnipeds represents the most significant cost to mothers during the reproductive cycle. Dynamics of trace elements and their mobilization associated with energy reserves during such an intense physiological process remains poorly understood in marine mammals. The changes in tissue concentrations of 11 elements (Ca, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, V, and Zn) were investigated in a longitudinal study during the lactation period and during the post-weaning fast period. Blood, milk, blubber, and hair samples were collected sequentially from 21 mother–pup pairs of grey seals (Halichoerus grypus) from the Isle of May in Scotland. Maternal transfer through the milk was observed for all trace elements, except for Cd. As an indicator of the placental transfer, levels in pup lanugo (natal coat) revealed also the existence of maternal transfer and accumulation of all assayed trace elements during the foetal development. The placental and mammary barriers against non-essential metal transfer to offspring appear to be absent or weak in grey seals. Examining the contamination levels showed that this grey seal population seems more highly exposed to Pb than other phocid populations (2.2mg/kg dw of grey seal hair). In contrast, blood and hair levels reflected a lower Hg exposure in grey seals from the Isle of May than in harbour seals from the southeastern North Sea. This study also showed that trace element concentrations in blood and blubber could change rapidly over the lactation period. Such physiological processes must be considered carefully during biomonitoring of trace elements, and potential impacts that rapid fluctuations in concentrations can exert on seal health should be further investigated.

Experimental study on friction and wear behaviour of amorphous carbon coatings for mechanical seals in cryogenic environment

The service life and the reliability of contact mechanical seal are directly affected by the wear of seal pairs (rotor vs. stator), especially under the cryogenic environment in liquid rocket engine turbopumps. Because of the lower friction and wear rate, amorphous carbon (a-C) coatings are the promising protective coatings of the seal pairs for contact mechanical seal. In this paper, a-C coatings were deposited on 9Cr18 by pulsed DC magnetron sputtering. The tribological performances of the specimen were tested under three sealed fluid conditions (air, water and liquid nitrogen). The results show that the coatings could endure the cryogenic temperature while the friction coefficients decrease with the increased contact load. Under the same contact condition, the friction coefficient of the a-C coatings in liquid nitrogen is higher than that in water and that they are in air. The friction coefficients of the a-C coatings in liquid nitrogen range from 0.10 to 0.15. In the cryogenic environment, the coatings remain their low specific wear rates (0.9×10−6 to 1.8×10−6mm3N−1m−1). The results provide an important reference for designing a water lubricated bearing or a contact mechanical seal under the cryogenic environment that is both reliable and has longevity.

Thermohydrodynamic Analysis of Spiral Groove Mechanical Face Seal for Liquid Applications

In this study, a three-dimensional thermohydrodynamic (THD) CFD model is developed to study the characteristics of an inward pumping spiral groove mechanical seal pair using a commercial CFD software CFD-ACE + . The model is capable of predicting the temperature distribution and pressure distribution of the seal pair. Based on the CFD model, a parametric study is conducted to evaluate the performance of the seal. It is found that thermal behavior plays an important role in the overall performance of a seal. The spiral groove parameter can be optimized to achieve desired performance. The optimization is dependent on the application requirement of the seal.

Mathematical modeling of the interference of seal pair in triple-offset butterfly valve

Avoiding interference of seal pair in triple-offset butterfly valve is critical to its performance and service time. In this article, a mathematical model is proposed for the seal interface. A formula is derived to evaluate the interference of seal pair in triple-offset butterfly valve. Five parameters are considered, including the diameter of valve disc, the effective sealing thickness, axial offset, radial offset, and eccentric angle. The influences of axial offset, radial offset, and eccentric angle on the interference area and position are investigated. The results show that the interference area decreases initially and increases finally when either the axial offset or the eccentric angle increases, whereas it decreases monotonously as the radial offset increases.

Design, operation and validation of a new fluid-sealed direct shear apparatus capable of monitoring fault-related fluid flow to large displacements

A new type of direct shear apparatus has been developed to allow for deformation of large and intact rock samples under fluid-sealed conditions. The sealed cell was specifically designed to monitor changes to fluid flow across the evolving rupture surface to large displacements (≤120 mm), and effective stress conditions up to 36 MPa. To maintain a seal for the pore fluid during deformation, a viscous and immiscible sealant fluid was injected at the interface between the rock specimen and the inner sample cell. Finite element modelling was conducted in parallel to verify the stress distribution in the specimen, notably the effect of geometrical constraints on the fault zone development and mechanical data. Results obtained from natural Castlegate sandstone, synthetically cemented sandstone and sandstone–clay composite blocks demonstrate the suitability of this equipment to investigating coupled fluid mechanical behaviour of a wide range of rock specimens. In particular, the test configuration is demonstrated to be capable of exploring fault-related fluid flow behaviour in reservoir–seal pair analogues with application for the hydrocarbon industry and the emerging field of carbon dioxide storage assessment.

Thermal Deformation in a Dry Gas Seal

In order to know thoroughly the thermal deformation characteristics of the dry gas seal in the synthesis gas compressor, the physical model and the thermal equilibrium model of the seal pair are established on its structural and thermal analysis. Based on finite element analysis software ANSYS, separation method are applied to resolve and analyze the temperature field and thermal-structural coupling deformation of the seal pair. The analyzed results show that the temperature of the rotating ring decreases gradually from the end face to the back face, and decreases gradually from the inner radius to the outer radius. The maximum of the temperature gradient of the rotating ring locates at the outer radius of the end face.The deformation of the stationary ring is negative conicity, the deformation of the rotating ring is positive conicity, and the later is the major reason of seal failure. Because of the thermal deformation, the end faces will form a convergent wedge. The convergent wedge favors the formation of a gaseous film, but it will lead to a increase in leakage quantity.

Exploring Operation Mechanisms of the Flexible Metal-to-Metal Face Seal: Part I—Numerical Modeling and Validations

A numerical model was developed for a special type of metal-to-metal face seal to evaluate its performance under various operating conditions. The model considers interactions among surface deformations due to thermomechanical twists, oil transport in the sealing band, and heat transfer in the seal pair simultaneously. In the meantime, experimental efforts have been made to measure the friction coefficients and seal temperatures during different operations. The model predictions were then compared with the experiment results through the two above-mentioned quantities. The comparisons show that the numerical simulations consistently overestimate the friction by 15–20%. However, the overall trend of friction variation with speed and some details of the friction have been captured, indicating that the current models are able to properly predict tribology of seal operations.

High performance encapsulation structures utilizing Russian Doll architectures

A Russian Doll encapsulation architecture utilizing pairs of free-standing barrier films and epoxy seals separated by nitrogen spacers is presented, enabling the use of low-cost epoxy to attach two or more free-standing barrier films to a substrate with improved barrier performance. The performance of various Russian Doll encapsulations was evaluated with the calcium thin film optical transmission test, showing improved performance of the Russian doll configuration relative to a non-nested barrier/spacer architecture, and demonstrating that water vapor transmission rates (WVTR) of 0.00021 g/(m 2, day) or below can be achieved with low-cost materials in this architecture. This WVTR correlates to a predicted lifetime of more than 10 years for bulk heterojunction solar cell modules fabricated and tested by Konarka Technologies (Lowell, MA, USA).

Depositional sequences and palynology of Triassic carbonate-evaporite platform deposits in the Palmyrides, Syria

Abstract This paper describes the results of new stratigraphic correlations and petroleum systems analyses of the Triassic deposits in the Syrian Palmyrides. The correlations are based on well data and new palynological work which reconcile previous lithological and stratigraphic miscorrelations of Triassic sequences from this region. The sequences are subdivided into four Megacycles, which are directly related to the key elements of the petroleum systems of the Palmyrides. The hydrocarbon discoveries within these systems, the fluid contacts and hydrodynamics are explained with reference to the Megacycle subdivision. This subdivision is applied on a regional scale and is used to define the distribution of reservoir seal pairs for volumetric estimations.

Lactational transfer of PCBs and chlorinated pesticides in pups of southern elephant seals (Mirounga leonina) from Antarctica

Seven pairs of southern elephant seals (Mirounga leonina) pups and their dams were sampled during the late weaning season among a breeding population of seals on Elephant Island in Antarctica. The blubber of the pups and the milk and blubber of their dams were analyzed for lipid-normalized concentrations of PCBs and organochlorines compounds in order to evaluate the lactational transfer of these contaminants. The lipid-normalized concentrations in these tissues were in the ppb range (i.e., ngg−1 lipid). The levels of contaminants in southern elephant seals were low in comparison with residues that have been reported in pinnipeds from the northern hemisphere. The relative tissue concentrations of the analytes measured followed the pattern: ΣDDT>mirex>ΣPCB>Σchlordane>HCB>heptachlor epoxide>dieldrin>methoxychlor>ΣHCH>other organochlorines. The very high DDE/ΣDDT ratio (0.91) in the blubber of dams and pups was an indicative of long-term, extremely distant pollution. On the other hand, the relatively high levels of some other organochlorine pesticides (e.g. mirex, heptachlor epoxide, dieldrin, methoxychor) may reflect the continued use of these insecticides in developing countries located in the southern hemisphere. For most of the analytes measured, the lipid-normalized concentrations were lower in pup blubber and in the milk than in the maternal blubber. Lactational transfer rates were dependent on the logKow (octanol/water partition coefficient) values of the analytes measured, less lipophilic compounds being more readily transferred to the pups by the lactational route.

Synthesis of the exploration of formations with a potential of CO2 storage: Intermediate Depression and Madrid Basin

Abstract As a part and continuation of the work that is being done under the GeoCapacity Project, Spanish Geological Survey (IGME) has developed a selection of CO2 storages in the great sedimentary basins of Spain. This presentation is a result of these studies in the Tagus River Basin, including the two zones in which this basin is traditionally divided in geological publications: Intermediate Depression and Madrid Basin. Using information from hydrocarbon exploration campaigns, mostly seismic and borehole logging, as a starting point, storage- seal pairs have been identified, attending to different criteria, such as depth, height, porosity or salinity of the formation water. Through the analysis of these parameters two geological formations have been selected as the most promising: Buntsandstein sandstone Formation, with a primary seal in Rot clays and a secondary seal in Keuper clays, and Utrillas sandstone Formation (Lower Cretaceous) with a seal in the Superior Evaporitical Formation (Upper Cretaceous). On the other hand, as a special case study of the GeoCapacity Project, a detailed study of a selected structure is being carried out in the Tagus River Basin, about 70 Km to the South East from Madrid. This structure is a long double-domed anticline detected under a thick Tertiary deposit that is not folded. Two different formations have been selected as potential storages: - Utrillas sandstone (L-M Cretaceous): It completely covers the extension of the structure, and it is sealed by Tertiary marls and gypsum. Average porosity varies from 7 to 18% and height is about 120 m at a depth of 1550 m. - Buntsandstein sandstone (L Triassic): It is only deposited in the Eastern dome of the structure, sealed by Rot clays of the Middle Triassic. Average porosity is 14% and height is about 50 m at a depth of 1700 m. Total capacity of the structure has been evaluated at a first stage in 812 Mt in the case both formations can be used as storage.

Polybrominated diphenyl ethers (PBDEs) in seal populations from eastern and western Canada: An assessment of the processes and factors controlling PBDE distribution in seals

Polybrominated diphenyl ether (PBDE) concentrations were measured in the blubber of five mother–pup pairs of grey seals ( Halichoerus grypus) from Sable Island, Nova Scotia (NS) sampled in 1995 and in 20 harbour seals (Phoca vitulina) from British Columbia (BC) sampled in 1991–1992. Concentrations in maternal grey seals from Sable Island averaged 112 ± 55.2 ng/g lipid (mean ± s.d.) and were over twice the concentrations measured in their pups; higher brominated PBDEs showed a distinct decline in PBDEs transfer efficiency in mother–pup pairs as a function of increasing K o/w. Hepta-BDEs and higher molecular weight (MW) congeners appear not to be transferred efficiently from the grey seals mother to pup during lactation on the basis of lipid/water partitioning (as indicated by ln K o/w) and this may be a consequence of molecular size (MW > 600 Da) which may limit diffusion and partitioning. PBDE concentrations in blubber from harbour seals from the Strait of Georgia averaged 319 ± 132 ng/g lipid (mean ± s.d., n = 13), while those from the more remote and less contaminated Quatsino Sd. averaged 27.8 ± 11.8 ng/g (mean ± s.d., n = 7). Tri- to hexa-BDEs were appreciably enriched in Strait of Georgia harbour seals relative to those from Quatsino Sd, suggesting that the former were closer to PBDE sources. The main congeners identified in all samples were BDEs 47, 99, 100, 153 and 154. Data were compared to those in ringed seals sampled from Holman, North West Territories (NWT), in 1996. The Holman samples had a higher proportion of lower bromination congeners, and a lower proportion of higher bromination congeners, than did the Sable Island and BC seal samples, consistent with selection in favour of more volatile compounds during atmospheric transport to the Arctic.