Italian seal manufacturer Fluiten has released double cartridge TRHD seals with metal bellows, developed specifically for pumps used at high temperature.
Fluiten’s R&D team designed the seals to be able to withstand temperatures of over 176°C, as stipulated by API standards, and they are also able to prevent any leakage of dangerous liquids into the atmosphere.
During the refining process of crude oil, the desulphurisation of naphtha is one of the high temperature processes which run considerable risks.
The chemical reaction takes place at a temperature of about 260°C with a pressure of 25-26 bar, with cobalt-molybdenum as catalyst.
At this temperature the sulphur molecules are removed from the naphtha with the use of hydrogen, which produces highly dangerous sulphite waste.
In heavy duty applications the mechanical seal is subject to axial and radial movement, and when the process liquid to be sealed exceeds a certain temperature, it is difficult to find a material for secondary gaskets (usually elastomeric O-rings) that withstands high temperatures without losing the necessary elasticity to accommodate the movement of the shaft.
Metal bellows are able to absorb this movement even at high temperatures as they do not include dynamic O-rings.
Elastomeric materials exposed to high temperatures undergo an irreversible chemical transformation which makes them solid, crumbly, and subject to cracking, making mechanical seals therefore unsuited for use in high temperature conditions.
The new Fluiten metal bellow seals are able to function in these challenging operating conditions in which elastomeric gaskets are impracticable, while complying with the API 682 4th ed. standards.