Bellows element

Meters. Diaphragms, diaphragm capsules, and bellows elements ate used extensively in meter bodies designed to measure differential pressure. These units can be used to measure the differences in pressure between two water lines, two steam headers, two stills, etc, from 25 Pa (0.1 in. H2O) to... 

Bellows Element The bellows element is an axially elastic cylinder with deep folds or convolutions. The bellows may be used unopposed, or it may be restrained by an opposing spring. The pressure to be measured may be applied either to the inside or to the space outside the bellows, with the other side exposed to atmospheric pressure. For measurement of absolute pressure either the inside or the space outside of the bellows can be evacuated and sealed. Differential pres-... 

Commercial bellows elements are usually hght-gange [of the order of (0.05 to 0.10 in) thick] and are available in stainless and other alloy steels, copper, and other nonferrons materials. Multi-ply bellows, bellows with external reinforcing rings, and toroidal contour bellows are available for higher pressures. Since bellows elements are ordinarily rated for strain ranges which involve repetitive yielding, predictable... 

Bell, Alexander Graham, 11 129 Bell furnace, 12 288-289 Bellows-actuated differential-pressure element, 20 651 Bellows elements, 20 650-651... 

The thin-wall bellows element should be designed for membrane stresses to conform to code-allowable stresses. The sum of membrane and secondary bending stresses should not exceed 1.5 times the yield stress in order to prevent the collapse of the corrugations caused by pressure. Bellows subjected to external pressure can be analyzed in a manner similar to a cylinder, utilizing an equivalent moment of inertia. The fatigue life can be estimated based on the sum of deflections and pressure stresses as compared to S/N curves based on bellows test data or using the curves in B31.3 Appendix X, Metal Bellows Expansion Joints. Formulas for the stress analysis of bellows are available in the Expansion Joints Manufacturing Association (EJMA) Standards (37). 

Bellows Element The bellows element is an axially elastic cylinder with deep folds or convolutions. The bellows may be used unop-... 

The converter consists of 1,536 pairs of thermopiles made of silicon-germanium alloy (Si 85% by mass, Ge 15% by mass) with n- and p-conductivity. Each module of 16 thermopiles is mounted on the inner surface of the hermetically sealed steel vessel. To provide for a good contact on the reactor heating, each module is pressed on the reflector by gas bellows elements. On the hot side, the keyboard consists of molybdenum plates, on the cold one - of copper bridges. To prevent an electric contact (shorting), insulating plates of beryllium oxide are used on the hot and cold sides. The excess heat is removed from the reactor-converter by shaped enamel-coated copper fins with an emissivity of at least 0.9 (O Fig. 59.2). 

The deflections of the complete bypass assembly model replicate the trends of the experimental data obtained by Games and Waterhouse for both the ambient and hot experiments. The maximum von Mises stresses occur along the topmost bellows elements. Some of these points appear to coincide with the locations of portions of the internal tear found in one of the recovered B4 bellows pieces. 

In the Claus process Sulphur Recovery Units, metallic bellow expansion joints in the tail gas line to Incinerator, seldom fail by developing crack on the bellow element due to various mechanical and metallurgical reasons. 

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. 

The most important feature of expansion joints is the multiple structure of the bellows elements. The bellows are manufactured as a multilayered tube of plies, ranging in number from 2 to 20, depending upon diameter and specified operating pressure. 

Using multiple plies of relatively thin gauge material means that lower residual stresses are introduced when the bellows element is formed. Also, the thinner multiple plies are subjected to lower operating stresses when compared to a single heavy fabric. Bellows therefore have lower built-in and operating stresses, which ultimately results in longer life. 

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