Metal-to-Metal Sealing for High Pressure Subsea Production System(SPS) Bolted Flange Connector

Metal to metal seal is one type of static seal used in high pressure Subsea Production System (SPS) Bolted Flange connector. Static sealing elements, as their classification implies, remain stationary relative to the surfaces they are sealing against. The subsea system can be located many miles away in deeper water and tied back to existing host facilities in shallow water. Due to the deeper water, higher challenges and problems need to be considered such as high reservoir pressures, low sea-bed temperatures, large variations in water depth range, flow assurance challenges, geo-hazard issue like gas hydrates, rough metocean condition, remoteness and hydrostatic pressure. The first objective is to analyze how leakages occur in SPS Bolted Flange connector. Bolt, flange and seal are the three main components in Bolted Flange connector that can contribute to the excessive leakage. Once excessive leakage happens in the deepwater, there will be loss in productivity, marine pollution and other important effects that need to be highly considered. From the literature reviews, main factors due to the seal that can cause leakage are inadequate overall flatness, inadequate smoothness and seal ring breakage can be concluded. The second objective is to propose and demonstrate the applicability of metal to metal sealing of SPS Bolted Flange connector for deepwater application. Temperature, pressure, industry design codes, life expectancy, leakage integrity and maintenance and accessibility are the key elements in selection of metal seal for SPS Bolted Flange connector. For this project, metal O-Ring has been chosen as the design for metal seal inside SPS Bolted Flange connector because its characteristics meet the deepwater and subsea requirements. The comparison has been made between Stainless Steel AISI 321, Alloy 600 and Alloy X750 by calculating the pressure exerted on the metal seal. All these materials satisfy subsea requirement but Stainless Steel AISI 321 has been chosen for metal ORing inside Bolted Flange connector due to cost consideration

The generation and classification of small leaks in a high pressure water system

This report investigates the detection of small leaks from the primary system of a Nuclear Pressurised Water Reactor. Leak rates of 12 g/s are invariably difficult to detect and locate. The typical leak indicators in a nuclear reactor control room are a drop in pressure and level from the pressuriser, and the air sampler detecting particulate matter. However, in both cases the leak is normally quite substantial by the time any parameters or values are obviously outside the normal operating conditions. Therefore, a small leak could go undetected for a significant amount of time. As part of the reactor safety studies, it is important to have more information about small leaks. Due to the lack of small leak data, the solution was to construct a high pressure water rig producing temperatures and pressures close to those experienced in the primary circuit, these being 200ºC and 100 bar respectively. Pressure is maintained by a vane water pump and heating is achieved by passing a high current through a small diameter, thin walled pipe. To reproduce different size cracks, various size carburettor jets are used. The water on exiting this crack, flashes to steam and immediately meets metallic pipe lagging, which is typical of most primary systems. With the typical crack scenario recreated it is now important to add sensors that will detect conditions associated with a small leak. These sensors are either mounted on or around the lagging material. The parameters that are monitored include vibrations, acoustics, thermal variations, moisture change, air flow and pressure adjustment leaving a predetermined outlet. The sensor outputs are pre-processed and the nonlinear data are applied to an artificial neural network, whereas the other data are applied to a digital logic system. The results showed that with 13 different leak rates, separated by only 1.4 g/s the ANN was able to correctly differentiate and identify different leak sizes with a certainty of over 97%. The results from all the analysis are further presented graphically through an Operator Advisory System. This informs the operator of the predicted leak size and location. All of the available sensor data relevant to the leak can be viewed and location of the leak is presented by a three dimensional model of the reactor system

Tribological Studies on Scuffing Due to the Influence of Carbon Dioxide Used as a Refrigerant in Compressors

The refrigeration and air conditioning industry has expressed a great interest in the use of carbon dioxide (CO2) as a refrigerant. CO2 is anticipated to replace HFC refrigerants, which are known to have a negative effect on the environment. The reason behind the interest in CO2 is the fact that it is a natural refrigerant, thus environmentally acceptable. Of course, such a replacement raises concerns regarding design criteria and performance due to the different thermodynamic properties of CO2 and the very different range of pressures required for the CO2 refrigeration cycle. So far, work related to CO2 has been done from a thermodynamics point of view and researchers have made significant progress developing automotive and portable air-conditioning systems that use the environmentally friendly carbon dioxide as a refrigerant. The purpose of this work is to develop an understanding of how CO2 plays a role from a tribology standpoint. More specifically, the goal of this work is to gain an understanding on how CO2 influences friction, lubrication, wear and scuffing of tribological pairs used in compressors. Work in the area of tribology related to CO2 is very limited. Preliminary work by Cusano and coworkers showed that consistent data for tests using CO2 could not be acquired nor could a satisfactory explanation be offered for the inconsistency. Their results triggered the initiation of the work presented here. In this first attempt to understand the tribological behavior of CO2 several problems were encountered. During this work we noted that its behavior, unlike conventional refrigerants, could not always be predicted. We believe that this can be attributed to the thermodynamic properties of CO2, which cannot be ignored when studying its tribological behavior. Thermodynamic Properties such as miscibility are very important when tribological testing is performed. A limiting factor with our tester was that it was not designed for CO2 testing, but for other conventional refrigerants and therefore made previously developed testing protocols non-applicable with CO2. Through a different approach and some modifications to our tester we were able to establish a protocol for testing under the presence of CO2. CO2 was then compared to R134a and the experimental results showed that it performs equally well.Air Conditioning and Refrigeration Project 13

Copper corrosion and its relationship to solar collectors:a compendium.

Copper has many fine qualities that make it a useful material. It is highly conductive of both heat and electricity, is ductile and workable, and reasonably resistant to corrosion. Because of these advantages, the solar water heating industry has been using it since the mid-1970s as the material of choice for collectors, the fundamental component of a solar water heating system. In most cases copper has performed flawlessly, but in some situations it has been known to fail. Pitting corrosion is the usual failure mode, but erosion can also occur. In 2000 Sandia National Laboratories and the Copper Development Association were asked to analyze the appearance of pin-hole leaks in solar collector units installed in a housing development in Arizona, and in 2002 Sandia analyzed a pitting corrosion event that destroyed a collector system at Camp Pendleton. This report includes copies of the reports and accounts of these corrosion failures, and provides a bibliography with references to many papers and articles that might be of benefit to the solar community. It consolidates in a single source information that has been accumulated at Sandia relative to copper corrosion, especially as it relates to solar water heaters

Development and operational experience of magnetic horn system for T2K experiment

A magnetic horn system to be operated at a pulsed current of 320 kA and to survive high-power proton beam operation at 750 kW was developed for the T2K experiment. The first set of T2K magnetic horns was operated for over 12 million pulses during the four years of operation from 2010 to 2013, under a maximum beam power of 230 kW, and $6.63\times10^{20}$ protons were exposed to the production target. No significant damage was observed throughout this period. This successful operation of the T2K magnetic horns led to the discovery of the $\nu_{\mu}\rightarrow\nu_e$ oscillation phenomenon in 2013 by the T2K experiment. In this paper, details of the design, construction, and operation experience of the T2K magnetic horns are described.Comment: 22 pages, 40 figures, also submitted to Nuclear Instrument and Methods in Physics Research,

In-Vessel Coil Material Failure Rate Estimates for ITER Design Use

The ITER international project design teams are working to produce an engineering design for construction of this large tokamak fusion experiment. One of the design issues is ensuring proper control of the fusion plasma. In-vessel magnet coils may be needed for plasma control, especially the control of edge localized modes (ELMs) and plasma vertical stabilization (VS). These coils will be lifetime components that reside inside the ITER vacuum vessel behind the blanket modules. As such, their reliability is an important design issue since access will be time consuming if any type of repair were necessary. The following chapters give the research results and estimates of failure rates for the coil conductor and jacket materials to be used for the in-vessel coils. Copper and CuCrZr conductors, and stainless steel and Inconel jackets are examined

Experimental assessment of expandable casing technology as a solution for microannular gas flow

Microannular gas flow in the wellbore is known to be one of the major reasons for Sustained Casing Pressure (SCP). Low success rate (under 50%) of costly remedial cementing operations and increasing difficulty in sealing off problematic areas motivated the industry to look for more practical remediation solutions. Expandable casing technology is one of those new proposed techniques. A bench-scale physical model tested the potential of expandable casing technology for remediation of microannular gas migration. The composite samples with pipe-inside-pipe cemented annulus were designed to simulate a wellbore system including a pre-manufactured microannulus on the inner pipe/cement interface. Multi-rate flow-through tests with nitrogen gas first evaluated the permeability and the size of the pre-manufactured microannulus. The post-expansion flow-through experiments tested the ability of pipe expansion in sealing the microannular gas flow. The effects of expansion on properties and structure of the cement were investigated by microindentation, optical microscopy, thermogravimetric analysis (TGA) and inductively coupled plasma (ICP) mass spectrometry. As observed with optical microscopy, the dissolution of unhydrated clinker grains during expansion is coupled with pore collapse within the cement sheath. Information obtained by microindentation showed that the cement sheath loses the integrity initially after expansion but regains most of the mechanical properties after a period of rehydration. Most important, multi-rate gas flow-through experiments showed that all three expansion ratios of 2%, 4% and 8% were successful in sealing the microannular gas flow. The seal was confirmed immediately and then 24 hours and 60 days after expansion. The findings in this research give solid support to the potential of expandable casing technology for remediation of microannular gas migration. Cement pore water propagation is the most likely driving force behind a successful expansion, one that is not an obstacle in subsurface conditions and also makes an ideal environment for cement rehydration post-expansion. Cement integrity should not be compromised by pipe expansion after certain period of rehydration. Finally, the research showed that expansion technology could be used during all operations in vertical and horizontal wells, whether injection or production wells, to mitigate well leaks caused by gas migration

Refurbished and 3D Modeled Thermal Vacuum Chamber

Spacecraft testing includes acoustics, vibrations, and thermal vacuum. Cal Poly’s Space Environments Lab is equipped with multiple vacuum chambers, but no thermal vacuum chamber. The purpose of this thesis is to incorporate an ATS Chiller system with the HVEC vacuum chamber so students are able to experiment with a thermal vacuum chamber. The ATS Chiller had leaky pipes that needed to be refurbished and a shroud was implemented to improve thermal capabilities of the system. The full system was able to reach temperatures as low as -38ºC and as high as 58ºC at a pressure of 10-6 Torr. The ATS Chiller was able to absorb up to 500W of heat dissipation from a component mounted to the platen inside of the vacuum chamber. Thermal modeling of the apparatus was performed in Thermal Desktop. The model was incorporated with the test data to extract interface resistance information between connected surfaces. Another model is used to analyze a theoretical component inside the apparatus to evaluate mounting methods and determine theoretical temperatures of the component. The model adjusts for material properties, including thermal conductivity and emissivity to accurately simulate testing conditions within +/- 3ºC. Platen and shroud adjustments were able to accommodate a peak bake out temperature of 130±2.2℃ of any component without damage to the system. Three temperature cycles were performed by the thermal vacuum chamber to reach extreme temperatures of 58℃ and -38. A 300 Watt heater was used to simulate component heat dissipation for the duration of the test. Furthermore, this thesis lays out further possibilities for thermal testing using the HVEC Vacuum chamber and ATS chiller as a thermal vacuum chamber

Simulator testing of evacuated flat plate solar collectors for industrial heat and building integration

The concept of an evacuated flat plate collector was proposed over 40 years ago but, despite its professed advantages, very few manufacturers have developed commercial versions. This paper demonstrates the reduction in heat loss coefficient and increase in efficiency resulting from evacuating a flat plate collector: it is hoped that these results will stimulate interest in the concept. Evacuated tubes are now mass-produced in large numbers; evacuated flat plate collectors could in principle replace these tubes if the technical difficulties in creating extended metal-glass seals can be overcome. The experimental experiences described here should indicate targets for future research. Two different designs of evacuated flat plate solar thermal collector, each with a 0.5 × 0.5 m flooded panel black chrome plated absorber, were tested under a solar simulator. The cover glasses were supported by an array of 6 mm diameter pillars. Inlet and outlet temperatures were monitored via PT100 RTDs and glass temperatures were measured using thermocouples. Inlet temperature was controlled by a fluid circulator connected to a header tank with a Coriolis mass flow meter to measure fluid flow rate. Testing was conducted indoors with and without the use of a fan to cool the top cover glass. The test conditions spanned the range 200 < G < 1000 W/m 2 , 0⩽T M ⩽52°C. Evacuating the enclosure reduced the measured heat loss coefficient by 3.7 W/m 2 K: this was a close match to predictions and corresponds to an increase in aperture efficiency from 0.3 to 0.6 at T M /G=0.06m 2 K/W. The poor efficiency under non-evacuated conditions was due to the black chrome absorber coating being less selective than commercial panel coatings. The solder seals were developed from experience with vacuum glazing but the increased gap led to reliability issues. A vacuum pump maintained the enclosures under a high vacuum ( < 0.1 Pa) during testing. The enclosure based on a thin rear metal tray proved to be more effectively sealed than the more rigid enclosure with glass on both sides: the latter developed leaks as the front to rear temperature difference increased. The biggest challenge in the manufacture of evacuated flat plate collectors is to ensure a long-term hermetic seal such that no pumping is required