Seals pressure

In order to contain normal or abnormal pressures, a pressure seal must be present. In hydrocarbon reservoirs, there is by definition a seal at the crest of the accumulation, and the potential for abnormal pressure regimes therefore exists. 

The movement-absorbing devices used in semirigid and nonrigid piping systems are usually called expansion joints. Based on the method by which the pressure seal is effected, joints are either of the packed type or the packless or bellows type. Selection depends not only on the required movement but also on the severity of service in terms of pressure and temperature, tolerabiUty of leakage, and the number of service cycles. 

Pressure-seal joints (Fig. 10-142) are used for pressures of 4.4 MPa (600 Ibf/in") and higher. They use less metal than flanged joints but require much more machining of surfaces. There are several designs, in all of which increasing fluid pressure increases the... 

Extracted from Face-to-Face and End-to-End Dimensions of Ferrous Valves, ANSI B16.10—1973, with permission of the publisher, the American Society of Mechanical Engineers, New York. To convert inches to millimeters, multiply by 25.4. tNot shown in ANSI B16.10 but commercially available. jTliese dimensions apply to pressure-seal or flangeless bonnet valves only. 

If ah systems are go, turn on the seal gas. Open the expander and eompressor ease drains to purge systems. Close drains and eheek seal gas pressure. Seal gas temperature must be 70-80°F downstream of the regulator. 

A reaction vessel explosion at BASF s resins plant in Cincinnati (July 19, 1990) killed one and injured 71. The BASF facility manufactures acrylic, alkyd, epoxy, and phenol-formaldehyde resins used as can and paper-cup liner coatings. The explosion occurred when a flammable solvent used to clean a reaction vessel vented into the plant and ignited. The cleaning solvent that was not properly vented to a condenser and separator, blew a pressure seal, and fdled the 80-year-old building with a white vapor cloud. 

Failure of the integrity of the DjO system in sequence 5 resulted from a small leak in the DjO system and failure of the operating personnel to isolate the leak which dominated the sequence. The probability of the small leak that challenges of the tank used to pressurize seals for the main circulating pumps was estimated to be 0.5 0.21 g. 

Type S is a floating head type. As the tubes heat up, they expand. As they expand, the floating head moves back and forth, but the pressure seal is not at the sliding joint. The pressure seal is at the fixed shell Joint in the outer head, which contains the pressure. The floating head floats free inside the pressure vessel as the tubes move. Types P and W are floating heads where the movement of the head effects the seal between either the shell-side or tube-side fluid and atmosphere. 

See Figure 12-9. The pressure seal between the cylinder pressure and the crank case or atmosphere is maintained by a packing gland. 

The next type of joint is weld overlays, which are often utilized to eliminate the need for costly thrust blocks [Fig. 4-2(p)]. In designing the pipe an analysis was made to ensure that it possessed sufficient longitudinal strength. It makes sense, then, to make the weld joints be at least as strong as the longitudinal strength of the pipe rather than just as an internal pressure-seal pipe. 

Semi-flexible Coupling Protects Drive Equipment and Pressure Seals... 

Adiabatic calorimetry. Dewar tests are carried out at atmospheric and elevated pressure. Sealed ampoules, Dewars with mixing, isothermal calorimeters, etc. can be used. Temperature and pressure are measured as a function of time. From these data rates of temperature and pressure rises as well as the adiabatic temperature ri.se may be determined. If the log p versus UT graph is a straight line, this is likely to be the vapour pressure. If the graph is curved, decomposition reactions should be considered. Typical temperature-time curves obtained from Dewar flask experiments are shown in Fig. 5.4-60. The adiabatic induction time can be evaluated as a function of the initial temperature and as a function of the temperature at which the induction time, tmi, exceeds a specified value. 

After weighing, the munitions are released to a four-unit vacuum purge station. Automatic vacuum/purge nozzles make a vacuum/pressure seal on top of the empty munitions, and a three-way automatic valve... 

Alloy 20 or Monel pump material and dual mechanical seals should be used with a pressurized seal oil system. 

A258 Seal chamber pressure SEAL PRESS N 13 kPa... 

Seal design. In higher-pressure seals, more than one outboard (i.e., high differential) sleeve may be used. Generally, it is desirable to use a single sleeve because the inboard sleeve operates with up to 80 percent of the total pressure drop across it. The outer sleeve with the lower differential causes lubrication and cooling problems that can shorten the life of one or both sleeves. 

A second method for monitoring the change in mercury level is the use of a follower probe. As the level decreases, electrical contact between the probe and the mercury level is broken. This actuates a drive motor which moves the probe, through a pressure seal, until contact is re-established. The drive motor angular displacement is proportional to the change in mercury level. 

Ferrofluids find several technical applications, which include rotary shaft seals, damping fluids, accelerometers, optical switches and shutters, and magnetic inks. The earliest application was in the construction of wear-free seals for rotary shafts. A similar seal is used in computer disc drives. Using ferrofluids, high-pressure differential seals which work in multiple stages have been constructed. When the seal is pressurized, each stage develops a momentary leak into the next chamber. The total pressure that can be contained is the sum of the pressure differences across all the stages. Pressure seals... 

In high pressure sealing in the oil field service, it should be noted that hardness, modulus, extrusion resistance and resistance to blistering under rapid decompression can all be increased with an improvement in cross link density. However the elongation is reduced, the elasticity diminished and so the sealing potential is lessened. 

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