mul211,

Most of the times when a constant spring has been sized for the support point, I had failed to provide adequate vertical space for a Figure 98 double stack spring. The required travel fit the capability of the Figure 98, but the selection could not be made due to the 'specified' space available. Height of Figure 98 springs can be more than 40 inches. The default selection is then the Constant effort figure spring. A user could specify available space to be 50 or even 100 inches, to avoid unnecessary selection of the constant type spring.

Only if the required travel exceeds 4 inches should a constant spring need to be used for that extreme travel.

Your system with 1200 deg F might require some re-routing to take the vertical runs in smaller steps, instead of having large vertical risers with vertical expansion greater than 4 inches in each riser step.