We have often heard people say, “Prevention is better than cure.” But have you ever thought of an equipment that inherently prevents and protects itself from a catastrophic damage?

About 8-10 years ago, a team of dedicated professionals at Funke attempted to design a heat exchanger that can detect the uninvited corrosion of its tubes, all by itself. Little did they know then that they were revolutionizing the domain of plant safety. With rising intensification, the chemical, process and allied industries, heat exchangers are meant to satisfactorily function in extreme operating conditions, ranging from a massive heat duty to handling of corrosive fluids. While the structural strength of a conventional shell and tube heat exchanger will eventually deter with time, it might pave way to cracks in its tubes, thereby hinting the occurrence of a catastrophe.

The safety heat exchanger (STHE) designed at Funke represents an excellent example of elegant engineering. The annular area, a characteristic feature of a double pipe heat exchanger, is put to use as a tool to check the safe operation of a STHE. The tubular arrangement consists of a corrugated inner tube, surrounded by another tube of slightly higher diameter. The inner tube is plastically deformed by subjecting it to hydraulic pressure while the material of construction of the outer tube is chosen in such a way that it doesn’t undergo plastic deformation. On sudden withdrawal of the hydraulic pressure, an annular area of vacuum results between the two tubes. The pressure in the annular region can be measured by means of a pressure gauge and is indicative of the safe operation of the heat exchanger. The presence of even a hair-line crack would disturb the vacuum in the annular region, leading to an irregular rise in the gauge pressure which is an indicative of surface corrosion.

But safety comes with a price. The guaranteed safe operation is associated with a decrease in the heat transfer capacity of the tube due to an irrational increase in its thickness. However, this can be compensated by increasing the length of the tubes which assures a higher heat transfer area.

With safety playing a pivotal role in almost every frontier of chemical engineering, this “Safety “, a brain-child of Funke, will most likely be welcomed by stalwarts in the field of chemical production and processing.