The Thermal Oil Systems have proved exceptionally safe during the many years in which they have been used in a wide range of applications. However, as in any industrial plant, proper sizing, perfect installation, correct operation, and careful maintenance are decisive for trouble-free operation and a long life of the system itself.

Excluding rare anomalous situations, the limited number of fires that can occur in thermal oil plants, occurs mainly in insulation, when they are not done in a workmanlike manner.

The fluid that escapes from the system from a valve, from a seal, from a welding or from the connection of an instrument, finds its way into the pores of the insulation and spreads, remaining at temperatures close to those of the line, and in contact with the air present in the pores of the insulating material.

As oil enters every pore, it oxidizes and decomposes, with a process that uses air and creates heat. If the loss of oil persists the continuous process, with the oil that continues to oxidize and increase in temperature until the self-ignition temperature of the oil can be exceeded.

If, in this situation, or because the insulator soaked in oil escapes from its protective sheath, or the sheath itself is opened for maintenance with the system in temperature, the fresh air that enters unexpectedly in contact with the hot fluid and partially oxidized can start fires with latent combustion, or with sudden flashes.

Selection, installation and maintenance criteria

We strongly recommend avoiding the use of threaded fittings as part of Thermal Oil Systems. With the wide degree of thermal expansion and contraction existing in high-temperature systems, combined with the temperature limit of sealing materials, losses are virtually guaranteed.

In areas prone to leakage (for example near valves, pumps, flanges and tool attachments), it is necessary to use closed-cell insulation for high temperatures, at best it is better to avoid insulation at critical points.

As far as the valve stems are concerned, we recommend to use the bellows, for pumps we suggest to use those without seal (of the magnetic drive type), or we suggest to use sets of seals made of carbon braid or graphite. A good choice for the flanges are the graphite seals reinforced by a thin stainless steel sheet.

During the installation of the system, four fundamental aspects must be kept in mind: the cleaning of the plant, the choice of components, the perfect tightening and tightness of the system and the possibility to correctly manage the expansion. System cleaning. The starting system must be clean and dry.