Leakage


In preliminary process design, the primary consideration is contact by inhalation. This happens either through accidental release of toxic material to the atmosphere or the fugitive emissions caused by slow leakage from pipe flanges, valve glands, and pump and compressor seals. Tank filling causes emissions when the rise in liquid level causes vapor in the tank to be released to the atmosphere.  [c.259]

Flux leakage probes Ultrasonic rotating scaimer (IRIS)  [c.325]

If a wire is broken, a leakage of the magnetic flow arises. The leakage can be detected by a magneto sensitive sensor, e.g. by a Hall generator, as an electric pulse while a rope moves near the sensor. Of course, the pulses from inner broken wires are less and longer than from outer ones.  [c.335]

Johnston D Aboveground storage tank floor inspection using magnetic flux leakage Material Perform t.31 no 10 1990 p.36-39.  [c.388]

The theoretical approach consists in having a maximal leakage flux allowing the drawing of the defect edge clearly.  [c.637]

Sizing of 3-D Surface Cracks with Complex Cross-Sections and Different Orientations Using Leakage Field.  [c.686]

ABSTRACT. Computations are made for sizing of surface eracks with complex cross-sections, unknown shapes, and different orientations with respeet to the applied field. An algoritlnn is used which computes unambiguously the width and the depth of a crack at six equidistant points of its cross-section, and the surface density of charge at the crack walls. Tlie algoritlim contains five minimisation procedures which are based on a regression for the distribution of the intensity of leakage field measured at a constant distance above the surface of the sample along the line which is parallel to the applied field and positioned over the centre of a crack. The crack width and surface charge density are always computed perfectly. The error in the computation of the depth profile of the crack is less than 20%.  [c.686]

A new electrical and magnetic method for sizing of surface flaws was proposed in The sizing is based on a regression between the distribution of the intensity of the leakage field measured at a constant distance above the surface of the sample along the line which is parallel to the applied field and positioned over the centre of a flaw and the eorresponding theoretical distribution of the intensity of the leakage field. It was demonstrated in that the method allows precise sizing of surface cracks with known shapes of their relatively simple cross-sections and arbitrary orientations with respect to the applied field. An algoritlim based on the method was developed in for sizing of cracks with complex cross-sections and unknown shapes when the cracks are oriented perpendicularly to the applied field. The algoritlim detennines the width and the depth of a crack at six equidistant points of its cross-section, and the surface density of charge at the crack walls.  [c.686]

It is assumed, according to the magnetic dipole representation that the crack is filled homogeneously with magnetic dipoles oriented parallel to the -x direction. Using the magnetic dipole representation, the following expressions were obtained for the z-component H of the intensity of the leakage magnetic field measured at a point with co-ordinates (x, y, z ) above the surface of the sample  [c.687]

Following the volume of a crack is represented as a sum of the volumes of sample s surface accessing tightly packed right-angular parallelepiped cracks with the same orientation which is characterised by the orientation angle d), and the leakage magnetic field of the crack is a superposition of the leakage magnetic fields of its constituent right-angular parallelepiped cracks. A crack with an arbitrary shape and orientation is sized by a regression based on minimisation of the root mean square error RMS between the measured distribution along tlie line which is parallel to the applied field and positioned over the centre of the crack and the conesponding theoretical distribution of the z-component of the intensity of the leakage field. At every step of the minimisation, new crack sizes are computed which generates a new theoretical distribution, while the RMS error decreases with the increase of the number of the minimisation step. The minimisation of the RMS error is performed using Nelder-Meade simplex seareh  [c.688]

The algorithm contains five minimisation procedures which are performed the same way as in the method " i.e. by minimisation of the RMS between the measured unidirectional distribution and the corresponding theoretical distribution of die z-component of the intensity of the leakage field. The aim of the first minimisation is to find initial approximations of the depth d, of the crack in the left half of its cross-section, die depth d in its right half, its half-width a, and the parameter c. The second minimisation gives approximations of d, and d and better approximations of a and c based on estimation of d,= d, and d,= d,j. Improved approximations of d] and d4 are determined by the third minimisation while fixing new estimations of d dj, dj, and dj. Computed final values dj , d/, a and c , whieh are designated by a subscript c , are provided by the fourth minimisation, based on improved estimations of d, dj, dj, and d . The fifth minimisation computes final values d, , d, dj, d while the already computed dj , d/, a and c are fixed.  [c.688]

The reason for these results is that the intensity of the leakage field and the RMS error used depend strongly on the parameter c and the crack width, and to a lesser extent on the depth profile of the crack. Also, the distribution of the density of the leakage field is measured over the centre of the crack and correspondingly changes more by varying of dj and dj rather than of d, dj, dj and d .  [c.691]

It is suggested though that even more precise sizing of cracks with complex cross-sections and unknown shapes could be achieved using the distribution of the leakage magnetic field along two lines positioned above the surface of the sample and parallel to the direction of the applied field at the same distance from the centre of the crack and from its closer end.  [c.692]

Due to the limitation posed by the initial electrical leakage signal and by the chosen angle of incidence of 52 deg. diffracted signals from 8 mm deep machined notch were hidden. Defects with depth exceeding 12 mm could be detected and sized. The same difficulty was observed when the thickness of the sample was less than 30 mm.  [c.725]

Principle of Magnetic Flux Leakage for detection of wall loss  [c.950]

In aero engines, material is often used near to its physieal limits. In order to ensure and improve the reliability of aero engines, eritical parts have to be tested in each state of their realization, ranging from materials development to deviee production and maintenance. Magnetic methods like eddy current tests, magnetic flux leakage tests and magnetic particle tests have proven to be powerful NDT tools. Since recently an extremely sensitive magnetometer system is available which can be operated with moderate effort. The key components of this system are SQUID magnetometers made from high-temperature superconductors. They can be operated while being cooled with liquid nitrogen which is non-expensive and such easy to handle as boiling water. This advanced SQUID system under normal circumstances does not need any magnetic shielding. This principally allows to test parts of unlimited size with reasonable tliroughput.  [c.988]

A gas/gas heat exchanger at a refinery had a known leakage, which it for technical reasons had been impossible to repair completely. The objective of the survey was to determine the leakage size in terms of the percentage of process stream crossing it.  [c.1057]

The size of the leakage was determined as follows. Radiation detectors were mounted on the inlet of the first side, and the outlet of the second side of the heat exchanger and at additional locations for control. A short pulse of Kr-85 tracer (<0.1 sec) was injected into the feed stream, which gave rise to detector responses shown in figure 3.  [c.1058]

Due to a limited axial dispersion, the first passages are sufficiently separated to calculated the leakage size directly, as the ratio between  [c.1059]

Tracer assisted leakage pigging in buried pipelines  [c.1059]

The methodology and the pigging tool have proven to be capable of identifying very small leaks. In oil pipelines like the Danish carrying 1500 m /h leakages down to 1 litre per hour can be detected without injection of large quantities of tracer. Leakages can be positioned with an accuracy of less than 1 metre.  [c.1060]

Final Technical Report, Thermie project OG/203/94, Development of a Novel Super Sensitive Leakage Inspection Pig for Inspection of Oil Pipelines , FORCE Institute, 1997  [c.1060]

A superconducting magnet consists of a cryostat, main coil, superconducting shim set and a means for attaching the current supply to the main coil (figure B1.12.4). The cryostat consists of two vessels for the liquid cryogens, an iimer one for helium and the outer one for nitrogen. Then, to insulate these, there are several vacuum jackets with a radiation shield. The aim is to reduce heat leakage to the iimer chamber to conserve helium. Superconducting magnets in NMR are usually operated in persistent mode, which means that, after a current is introduced, the start and end of the main coil are effectively connected so that the current has a continuous path within the superconductor and the power supply can then be discoimected. To achieve this the circuits within the cryostat have a superconducting switch. The coil circuits are also designed to cope with a sudden, irreversible loss of superconductivity, tenned a quench. There are resistors present (called dump resistors) to disperse the heating effect and prevent damage to the main coil when a quench occurs.  [c.1473]

By the time the oxygen stream has reached the absorption tubes its initial excess pressure ca. 6 cm. of water) has been almost completely dissipated by the resistance afforded to its passage by the packing of the combustion tube. The purpose of the Mariotte bottle is not only to indicate the rate of flow of gas through the apparatus, but also to create a slightly reduced pressure on the far side of the absorption train and so to draw the gas through the absorption tubes. The fact that the pressure inside the apparatus is equal to atmospheric pressure at the place where absorption begins, reduces the chance of leakage of carbon dioxide out of the apparatus and of leakage of water vapour into it. The reduced head in the Mariotte bottle is the difference in level between the bottom of X and the tip of Y, and is adjusted so as to give an initial flow of oxygen through the apparatus of 5 ml. /min.  [c.472]

A very significant source of pollution is formed by the organic solvents, which are used in much larger quantities than the solutes they carry and have a tendency to escape into the environment through evaporation and leakage. Halogenated solvents are particularly notorious with respect to their toxic character and poor biodegradability. A lot of research is currently devoted to the development of solvent-free systems or replacement of the solvent by a less environmentally hazardous one. Water is ideally suited for this purpose owing to its non-toxic character. Its enormous abundance on this planet makes water a readily accessible alternative. There are also advantages from an economic point of view.  [c.1]

By the time the oxygen stream has reached the absorption tubes its initial excess pressure (ca. 6 cm. of water) has been almost completely dissipated by the resistance afforded to its passage by the packing of the combustion tube. The purpose of the Mariotte bottle is not only to indicate the rate of flow of gas through the apparatus, but also to create a slightly reduced pressure on the far side of the absorption train and so to draw the gas through the absorption tubes. The fact that the pressure inside the apparatus is equal to atmospheric pressure at the place where absorption begins, reduces the chance of leakage of carbon dioxide out of the apparatus and of leakage of water vapour into it. The reduced head in the Mariotte bottle is the difference in level between the bottom of X and the tip of Y, and is adjusted so as to give an initial flow of oxygen through the apparatus of 5 ml./min.  [c.472]

Cud added. Insert the claisen head adapter into the flask. Be sure to apply some vac-grease to the joints. Place the addition funnel In the center hole. Add the 500 grams of safrole fo the funnel, but don t start adding it to the stirring solution. Next fill the balloon up with O2. She said that she filled it up pretty tight, but don t blow it up. Carefully attach the balloon to the remaining open hole on the claisen adapter and then TAPE or wire it to prevent any leakage. For those of you that don t have access to various pieces of glassware, placing the balloon on the addition funnel will woik as well. This was described in the book, Total Synthesis, pages 52 to 55.  [c.67]

You let the solution stir for 1-1/2 hours so it absorbs as much O2 as possible before you start adding the safrole. Everything is kept at room temperature for this procedure. The stirring solution looks very dark, almost black in color. Now slowly add the safrole from the addition funnel so that it takes about 60 minutes for the 500 grams to drip in. There is no noticeable reaction as the safrole is dripped into the stirring solution. Once this is completed let it stir away for the next 24 hours. Note In her dream, she checks the balloon at the 12-hour mark. It has gone down in size as O2 is being absorbed by the stirring solution. She inflated another balloon, removed the one that had been on there for the past 12 hours and placed the new, full balloon on the open hole. Tape or wire it so there s no leakage. This ensures an adequate 62 atmosphere while the process finishes (excessive, yes, but cheap and simply). She noted that after 3-4 hours of stirring the solution changes from a dark almost black color to a dark sea green or dark olive green in color.  [c.67]

If and when these difficulties can be overcome, the way will be opened to the employment of adsorptives which have a vapour pressure high enough to enable their isotherms to be measured at temperatures close to ambient. This would substantially reduce the effect of thermal leakage and with it the distortion of the isotherm in the region near saturation.  [c.167]

When a block is inside, the entrance panel is closed and the inspection is ready to start. The inside of the stainless steel X-ray tubehead housing is clad in lead with an on/ofT shutter in front of a thin plastic X-ray window. The thin window is to ensure the IP 65 classification. The window is of plastic that is not affected by the cleaning agents. The on/off shutter is interlocked with the entrance and exit panels so X-rays can be kept on at all times without risk of radiation leakage or exposure of the frozen fish blocks prior to the actual inspection.  [c.591]

Magnetic particles is one of the most used nondestructive testing techniques in industry. It allows detection and localization of surfacic and subsurfacic defects of ferromagnetic pieces by making conspicuous leakage fields by a magnetic developer.  [c.635]

The method seirsibility depeird essentially on the poles force attraction which exists at the position of the defect. This attraction force depend on the value of the leakage field, so of the magnetic exciting field which has created them.  [c.638]

It is assumed in the following computations that The orientation angle and the length 21 of the cracks are measured independently The measured distributions considered are simulated for c= 0 A/m while the volumes of the investigated cracks are replaced by a sum of the volumes of one hundred tightly packed right-angular parallelepiped cracks with the same length 21/100 and width 2a The intensity of the leakage magnetic field is measured at 100 points positioned equidistantly along the x axis for y=0 at a distance z=0,5 mm above the surface of the sample and centred around the long axis of the crack Botli a and c are considered to be unknown when theoretical distributions are generated while the volumes of the investigated cracks are represented as a sum of the volumes of six tightly packed right-angular parallelepiped cracks with the same length 21/6 and width 2a as shown in Fig.4a and Fig,4b,  [c.690]

A third inspection technique, which is not new at all, but has been used for some decades now in intelligent pigs for gas transport pipelines all over the world, is the Magnetic Flux Leakage (MFL) method, see figure 4. Metal loss is detected because it generates a weak leakage field in a magnetically saturated pipe or vessel wall. This leakage field is picked up by sensors and electronically processed and displayed. The MFL technique was first applied to storage tank floors about ten years ago, in an inspection system called Floorscatmer, developed in the UK. But the spin-off applications are just as valuable quick corrosion detection in pipe and vessel walls, as a screening method to find suspect spots and mark those for further evaluation.  [c.950]

Fractionating columns of greater efficiency than the simple Vigreux column are illustrated in Figs. II, 15, 2, II, 15, 3 and II, 15, 5. The all-glass Dufton column (Fig. II, 15, 2) is a plain tube into which a solid glass spiral, wound round a central tube or rod, is placed. The spiral must fit tightly inside the tube in order to prevent leakage of any appreciable amount of vapour between the walls of the column and the spiral this is best ensured by grinding the edges of the spiral into the tube. Typical dimensions are spiral, 15-30 cm. long fitted Inside a tube of 20 mm. diameter hollow tube, sealed at both ends and round which the spiral is tightly wound, 13 mm. external diameter turns of glass spiral, 10-13 mm. apart. The Hempel column (Fig. II, 15, 3) is a simple glass tube, 30-40 cm. long and 15-25 mm. diameter, fiUed to within 5 cm. of the side arm with a suitable packing. For general use J" X i" hollow glass rings (or a smaller size, if available) are quite satisfactory. Excellent packings for columns may be purchased either in  [c.91]

The high-pressure water supply service is employed for the operation of the ordinary filter pump, which finds so many applications in the laboratory. A typical all metal filter pump is illustrated in Fig. 11, 21, 1. It is an advantage to have a non-return valve fitted in the side arm to prevent sucking back if the water is turned off or if the water pressure is suddenly reduced. Theoretically, an efficient filter pump should reduce the pressure in a system to a value equal to the vapour pressure of the water at the temperature of the water of the supply mains. In practice this pressure is rarely attained (it is usually 4 10 mm. higher) because of the leakage of air into the apparatus and the higher temperature of the laboratory. The vapour pressures of water at 5°, 10°, 15°, 20° and 25° are respectively 6-5, 9-2,12-8, 17 5 and 23 8 mm. respectively. It is evident that the vacuum obtained with a water pump will vary considerably with the temperature of the water and therefore with the season of the year in any case a really good vacuum cannot be produced by a filter pump.  [c.110]

The thermal conductivity of silica aerogels can be further reduced by minimising the radiation leakage with an opacifter such as carbon black (54). The introduction of an opacifter makes the material opaque and unsuitable for window insulation. On the other hand, opaque silica aerogels can be used as insulating materials in appHances such as refrigerators and freesers. Compared with CFC-blown insulating foams, which could release chlorine into the atmosphere, silica aerogels pose no such environmental hasard and are nonflammable. Moreover, the thermal conductivity of opaque silica aerogels is a weak function of temperature (52), making them useful as insulating materials for heat-storage systems. Another promising appHcation of silica aerogels is as a filler in vacuum panel because they do not require a high vacuum for good thermal performance. The high surface area of these materials further allow them to act as a "getter" by adsorbing gases in the panel.  [c.7]


See pages that mention the term Leakage : [c.141]    [c.177]    [c.43]    [c.723]    [c.1058]    [c.1058]    [c.1059]    [c.1059]    [c.1449]    [c.1462]    [c.66]    [c.217]    [c.473]    [c.559]   
Turboexpanders and Process Applications (0) -- [ c.0 ]

Advanced control engineering (2001) -- [ c.0 ]

Industrial ventilation design guidebook (2001) -- [ c.788 , c.878 , c.1088 , c.1406 , c.1426 , c.1430 , c.1436 , c.1451 , c.1453 , c.1455 , c.1478 ]