Prevention of thermo-hydraulic rupture of solvent transfer pipes in the pharmaceutical industry

Solvent transfer pipes in pharmaceutical plants can be susceptible to thermo-hydraulic rupture. This mode of failure, arising from the restraint of thermal expansion of a trapped liquid, can lead to serious safety and environmental consequences. In the paper, an approach to eliminate the problem by the inclusion of short lengths of flexible elastomer hose in conventional stainless steel pipelines is explored. As atmospheric heating is unpredictable, a stochastic thermal model is used to calculate the distribution in temperature rise in the trapped solvent that may be reasonably expected. From this temperature rise, the pressure developed in the solvent and the corresponding membrane stress in the pipe wall can be found. By defining a maximum acceptable stress level, the fractional length of hose that must be incorporated in the system can be determined.