Bellows expansion joints

FIG. 10-172 Constrained-bellows expansion joints. (From Kellogg, Design of Piping Systems, Wiley, New Yotk, 1965.)... 

If possible, eliminate inherently weak equipment like sight glasses, hoses, rotameters, bellows, expansion joints, and most plastic equipment. The spare parts consumption from the shop and warehouse will indicate what is wearing out. 

At the Flixborough plant there were six reactors in series. Each reactor was slightly lower than the one before so that the liquid in them flowed by gravity from No. 1 down to No. 6 through short 28-in.-diameter connecting pipes (Figure 2-5). To allow for expansion, each 28-in. pipe contained a bellows (expansion joint). 

Bellows (expansion joints) are a good example of equipment that is intolerant of poor installation or departure from design conditions. They... 

X Factor for modifying the allowable stress range, S for bellows expansion joint (see para. IP-3.8.4 for further details) ... 

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 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). 

Jakubauskas, V. F., and D. S. Weaver. 1998a. Transverse Vibrations of Bellows Expansion Joints. Part I Fluid Added Mass, Journal of Fluids and Structures, voL 12, pp. 445-456. 

Newland, D. E. 1964. Buckling of Double Bellows Expansion Joints imder Internal Pressure, Journal of Mechanical Engineering Science, vol. 6, pp. 270-277. 

Newland, D. E. 1976. Buckling and Rupture of the Double Bellows Expansion Joint Assembly at Flixborough, Proceedings of Royal Society of London, series A, vol. 351, pp. 525-549. 

Snedden, N. W. 1985. Analysis and Design Guidance for the Lateral Stiffness of Bellows Expansion Joints, Thin-Walled Structures, vol. 3, pp. 145-162. 

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. 

Local loads at piping connections shall be considered in the design of the tank shell. Moreover, the piping shall be designed to minimize unfavorable effects of interaction between tanks and other structures. Mechanical devices which add flexibility to the piping connection, such as bellows, expansion joints, and other flexible components, may be used when they are designed for seismic loads and displacements. 

---