Archives for August 2017

CERN (Conseil Européen pour la Recherche Nucléaire) is located in a northwest suburb of Geneva, Switzerland and is the world’s leading center for collaboration on nuclear research. One of its many activities involves the study of  particle physics.

Particle physics is conducted in machines known as particle accelerators (aka particle colliders). These use electromagnetic fields to accelerate particles to high speeds and focus them into a fine beam. The world’s largest and most powerful particle accelerator, the Large Hadron Collider (LHC) began operation at CERN in 2008. The LHC (Figure 1) is a 27 kilometer (16.8 mile) ring of superconducting magnets held at temperatures colder than outer space. Within this machine subatomic particles smash together at near light speed in an ultrahigh vacuum. It has allowed scientists unique insights into the fundamental building blocks of matter

Vacuum furnaces come in all shapes and sizes but common to each is that they require some type of vacuum vessel (Fig. 1). Most vacuum vessels in the heat treating industry are cylindrical in shape and either horizontal or vertical in orientation (Fig. Nos. 2 – 3). In general, vacuum vessel designs are made as small as possible so long as they don’t hamper the process being run in the vessel. There are several obvious reasons for this including the cost of the vessel itself as well as the vacuum hardware involved. In addition pumping systems become larger and operating costs tend to be higher (e.g. more gas is required for quenching).

Designs for vacuum vessels involve two distinct aspects; one structural and one related to the process application. The basic structural design falls in the realm of mechanical engineering following established industry guidelines, an example of which is the ASME Boiler and Pressure Vessel Code, Section 8 Division 1 (Rules for Construction of Pressure Vessels) for vacuum furnaces utilizing high-pressure gas quenching (above 14.7 psig). The design must take into account both the external and internal forces acting on the vessel to prevent buckling (i.e. structural instability) and deal with overpressure issues, both major concerns from a strength of materials standpoint.