On the Strength of the Cross Stay Reinforcing the Outer Firebox of a Loco-Type Boiler

Abstract

For the cross stays provided in the neighbourhood of the line where the semi-circular crown plate of a loco-type boiler and its flat side plates are joined, no designing formula has been specified in any Rules or Regulations. Therefore, the authors, carrying out the theoretical analyses and experiments, could establish the designing formulae and moreover make the following matters clear. (1) The semi-circular crown plate itself, if not connected to the inner firebox by crown stays, is in equilibrium with internal pressure. Consequently it is sufficient for cross stays to be designed so as to support only the flat portion below the stays. (2) In the case of a boiler having crown stays, the design of cross stays should be carried out considering the additional force due to the downward pull of crown stays acting on the crown plate. (3) The lower part of fireboxes must be carefully designed to prevent the early substantial destruction of vessel.