Calculation of the saddle for overlapping equipment

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1. In accordance with standards such as GB/T 151-2014 \"Heat Exchangers\", NB/T 47042-2014 \"Horizontal Vessels\", and NB/T 47065.1-2018 \"Vessel Supports – Part 1: Saddle Supports\", relevant calculation methods are specified for the saddles of individual devices; however, no corresponding calculation methods are provided for devices with overlapping saddles. For the calculation of the saddles for overlapping equipment (heat exchangers), the following aspects can be referred to for design and calculation: Standards and specifications: In accordance with the provisions of GB/T 151-2014 \"Heat Exchangers\", the design of the saddles requires verification of their strength and stability; the saddles can be selected in accordance with NB/T 47065.1. Mechanical model and analysis: The stacked equipment (heat exchanger) can be considered as a simply supported beam with two concentrated loads applied to its barrel, these loads being transmitted from the upper heat exchanger to the lower equipment (heat exchanger). The stresses that need to be checked include the axial bending moment, the axial stress generated by vertical shear forces, shear stress, as well as the circumferential compressive force and circumferential bending stress caused by shear stress. 2. Below is an introduction to the methods I generally use to verify the strength and stability of the equipment saddles and shells for overlapping heat exchangers (these are merely my personal experience cases for reference only). For the calculation of the saddles of overlapping heat exchangers, I generally use the module for \"asymmetric double saddles and multiple saddles in horizontal vessels\" in SW6. The specific calculation steps and adjustment methods are as follows: a) Calculation steps: ⑴ First, carry out the calculation for the upper heat exchanger saddle. The tube bundle of the heat exchanger is treated as a uniformly distributed mass, while heavier components such as the tube sheet or equipment flanges can be considered as concentrated masses. This calculation must include assessments of the saddles under design conditions (including both non-seismic and seismic conditions), as well as under pressure test conditions ；  ⑵Generate the calculation sheet for the upper heat exchanger saddle.  ⑶When calculating the bottom heat exchanger, the upper heat exchanger must be considered as a lumped mass at this time. Ⅰ. Take the reaction force at each saddle under the design conditions of the upper heat exchanger (in the seismic-free condition), divide it by g to obtain the mass of the particle in kilograms; these values are then used as concentrated masses to be applied to the lower heat exchanger. The height of this concentrated load should correspond to the centerline height of the upper heat exchanger, while its horizontal position should match the horizontal position of the saddles on the upper heat exchanger. In addition, the uniform and concentrated loads acting on the bottom heat exchanger itself must be taken into account in the calculations; the calculation report should only include the input data as well as the design conditions (without seismic loads) and the design conditions (with seismic loads).  II. Take the saddle reaction under the design operating condition of the upper heat exchanger (seismic condition) for the same calculations as above ；  III. Use the reaction force under the pressure test conditions of the upper heat exchanger for the same calculations as above ；  ⑷By combining the strength calculation document for the upper heat exchanger saddle with the calculation documents from sections I, II, and III above, one obtains the calculation document for the support system of the entire equipment.  b) How to make adjustments if the calculation for the overlapping saddle fails: When the calculations of the axial or circumferential stress in the cylinder using the saddle method do not meet the requirements, the following two solutions can be considered: I. Increase the wrap angle of the saddle ； II. Add an external reinforcing ring at the saddle.