Our client requested that we provide expert opinion on the effect of non-functioning counterweight heater coil supports. The inter-heater system was expanded a few years prior to our engagement to increase capacity. The new interheater was very similar to the existing interheater and was designed so that the manifold length and number of coils was doubled. Subsequently, an inspection of the old interheater indicated that the counterweight supports under the manifold between the spring supports were bottomed out and were essentially ineffective. It was unknown whether this condition existed prior to the installation of the new interheater.
A finite element model which included all systems connected to the interheater was built. The CCR was simulated with a beam model to capture the effect of the thermal expansion of the CCR and it's influence on the interheater piping. We found that the ineffective counterweights had a small but non-negligible effect on the fatigue life of the coils.