Bellows expansion type

The selection and application of an expansion joint is not as simple as selecting a pipe fitting or a valve and requires a sound understanding of the joint s capabilities and limitations. Improper application of any type of joint can result in serious or damaging effects. However, when properly selected and integrated into the piping system, satisfactory service and safe operation can be expected. Selection and application of bellows expansion joints require special attention to design and installation. 

The above SRU, designed on the basis of modified Claus process, is equipped with a tail gas Incinerator of natural draft, sub-atmospheric pressure type thermal incinerator with air flow controlled using burner air registers. Tail gas inlet line to the incinerator is installed with a Tied Universal type metallic bellow expansion joint to accommodate line expansion and movements. This expansion joint made out of Inconel-65 metallurgy was in operation since Year 2005 which subsequently during May-2011 had developed a crack on the metallic bellow element and started leaking toxic tail gas to atmosphere. 

Control loop design uses the five elements of the control loop. The one area that changes consistently is the first primary elements and sensors. Pressure control loops use devices to detect pressure changes. These primary elements are typically expansion-type devices. Primary pressure elements include bourdon, helical, spiral, bellows, pressure capsule, and diaphragm. Figure 8-3 shows a pressure transmitter, controller, transducer, and control valve. 

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. 

Dual-beUows assembhes, ie, universal-type expansion joints, are particularly vulnerable to squirm, and can experience elastic squirm at one-fourth the pressure of an individual bellows. When large amounts of offset are encountered, as is often the design basis, a pinwheel effect occurs because of unbalanced pressure forces. This effect tends to rotate the center-spool pipe which may lead to bellows mpture. Eor this reason the center spool should always be stabilized by hinges or tie-rod lugs to prevent such rotation. 

Bending or torsional flexibihty may be provided by bends, loops, or offsets by corrugated pipe or expansion joints of the bellows type or by other devices permitting rotational movement. These devices must be anchored or otherwise suitably connected to resist end forces from fluid pressure, frictional resistance to pipe movement, and other causes. 

Pressure thrust, which is the product of the effective thrust area times the maximum pressure to which the joint will be subjected during normal operation. (For shp joints the effective thrust area shall be computed by using the outside diameter of the pipe. For corrugated, omega, or disk-type joints, the effective thrust area shall be that area recommended by the joint manufacturer. If this information is unobtainable, the effective area shall be computed by using the maximum inside diameter of the expansion-joint bellows.)... 

Chemical-plant exchangers requiring expansion joints most commonly have used the flanged-and-flued-head type. There is a trend toward more common use of the light-wall-bellows type. 

Bellows couplings consist of two shaft hubs connected to a flexible bellows. This design, which compensates for minor misalignment, is used at moderate rotational torque and shaft speed. This type of coupling provides flexibility to compensate for axial movement and misalignment caused by thermal expansion of the equipment components. Figure 59.7 illustrates a typical bellows coupling. 

A piping system containing expansion joints shall be leak tested without temporary joint or anchor restraint at the lesser of 150% of design pressure for a bellows-type expansion joint or the system test pressure determined in accordance with para. IP-10.6. In no case shall a bellows-type expansion joint be subjected to a test pressure greater than the manufacturer s test pressure. 

If unbalanced layouts cannot be avoided, appropriate analytical methods must be apphed to assure adequate flexibility. If the designer determines that a piping system does not have adequate inherent flexibility, additional flexibility may be provided by adding bends, loops, offsets, swivel joints, corrugated pipe, expansion joints of the bellows or slip-joint type, or other devices. Suitable anchoring must be provided. 

Slip-type expansion joints (Fig. 10-178) substitute packing (ring or plastic) for bellows. Their performance is sensitive to adequate design... 

Other resistance-type transducers combine a bellows or a bourdon tube with a variable resistor, as shown in Figure 6. As pressure changes, the bellows will either expand or contract. This expansion and contraction causes the attached slider to move along the slidewire, increasing or decreasing the resistance, and thereby indicating an increase or decrease in pressure. 

Corrosion problems have also occurred in compressors, sour water valve trims, expansion bellows, and hydrocracker fractionators. Type 4140 (UNS G41400) compressor impellers have sulfide cracked in sour gas when the hardness exceeded 235 Brine)i(e>. Hardened 12Cr valve trim has sulfide cracked to prevent this problem, 18Cr-8Ni SS trim in sour water service is commonly used. Sulfide cracking has not occurred significantly in pumps. 

Foam films are usually used as a model in the study of various physicochemical processes, such as thinning, expansion and contraction of films, formation of black spots, film rupture, molecular interactions in films. Thus, it is possible to model not only the properties of a foam but also the processes undergoing in it. These studies allow to clarify the mechanism of these processes and to derive quantitative dependences for foams, O/W type emulsions and foamed emulsions, which in fact are closely related by properties to foams. Furthermore, a number of theoretical and practical problems of colloid chemistry, molecular physics, biophysics and biochemistry can also be solved. Several physico-technical parameters, such as pressure drop, volumetric flow rate (foam rotameter) and rate of gas diffusion through the film, are based on the measurement of some of the foam film parameters. For instance, Dewar [1] has used foam films in acoustic measurements. The study of the shape and tension of foam bubble films, in particular of bubbles floating at a liquid surface, provides information that is used in designing pneumatic constructions [2], Given bellow are the most important foam properties that determine their practical application. The processes of foam flotation of suspensions, ion flotation, foam accumulation and foam separation of soluble surfactants as well as the treatment of waste waters polluted by various substances (soluble and insoluble), are based on the difference in the compositions of the initial foaming solution and the liquid phase in the foam. Due ro this difference it is possible to accelerate some reactions (foam catalysis) and to shift the chemical equilibrium of some reactions in the foam. The low heat... 

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