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The present work forms part of investigations being made by NIIkhimmash (Research Institute for Chemical Plant) to develop standards and design methods for the strength of shells and bottoms of vessels and plant which will take account of the effect of localized plastic deformation in regions where edge effect is manifest. Vessels have been studied, similar to industrial plant, having different variations in the manner of joining jackets to the main body of the vessel (see Table 1). In these tests, the extent of deformation of cylindrical shells where the jacket joins the main body of the vessel, the strain or deformation pattern in the shell as affected by the construction of the junction, the bursting pressure, and the nature of bursting failure was determined together with measurement of residual plastic deformation in the shells. The plant under test was loaded in two stages; the jacket pressure being taken to 10 kgf/cm 2 and the main vessel pressure to 20 kgf/cm 2 in the first stage; these, respective pressures being raised to 15 kgf/cm 2 and 25 kgf/cm 2 for the second stage of test. It should be noted that the maximum pressure in the main body of the equipment corresponds to the permissible design pressure, while the jacket pressure was dictated on the basis of usual ratios of pressure in the jacket to that in the main body of the vessel in industrial reaction vessels.After stage-wise loading of the plant and making strain measurements at each step, the pressure in the main body of the vessel was kept constant while the jacket pressure was increased to the point of failure of the equipment. This method of failure was chosen as the result of analysis of cases of failure of industrial equipment incorporating jackets. Pressure was applied hydraulically, using a type RPN-2-500 ram pump. Pressure in the main body of the vessel was measured by pressure gage, pressure in the jacket was measured using a pressure transducer with the signal displayed on a single-coordinate recorder incorporating a type EPP-09 potentiometer.Strain measurements on the plant were made using special "plastic deformation" strain gages developed by NIIkhimmash [1]. Miniature strain gages having 3.5 mm gage-length were used for measuring strains in the vessel shell. These were bonded along the shell, pitched 7 mm apart over a zone 70 mm long from the point where the stiffening junction ring or the jacket itself was welded to the shell. Strain in the jackets was measured using 10 mm gage-length strain gages at a zone 150 mm long over the contour of the shell. In order to enhance the reliability of the tests, duplicate strain gages were bonded to a similar pattern on the opposite contour of each shell.The strain gage reading s were recorded by a type IPD-1, electronic, "plastic deformation" data logger (built by NIIkhimmash) with 150 point multi-channel switching.When processing the test results, note was taken of the pattern of the stress-strain state. Within the elastic region, stress was computed by plane stress formulas. The stresses at t...

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