CHETRA Mechanical Seals for the Chemical Industry

Improvement of Service Life – even in Connection with Curing Media and High Solids Content

The impetus for this project was the stipulation to improve substantially the MTBF factor of 13 months in the operation of 360 pumps in a phenol distillation plant. The ten “bad actors” were refitted with CHETRA double mechanical seals style 821 with appropriate accessories (API plan 53).

Special requirements arose from the medium to be sealed, as it had a high solids content and a curing at < 260° C. After the retrofit was accomplished, the total MTBF factor of all the pumps improved to > 30 months.


Custom-made Solution for Worldwide Applications

The mechanical seal has to fulfill special requirements when pumping MDI (diphenylmethane diisocyanate), an essential raw material for PUR applications resp. insulation plastic foams. Due to massive problems with seals in the above-mentioned application, CHETRA developed a custom-made, multiple-stage shaft seal for one of the largest manufacturers in the chemical industry.

The successful application in the German plant prompted the manufacturer to employ this CHETRA seal design in all his MDI plants worldwide.


No Auxiliary Cooling – Sealing at 400° C

Mineral oil-based and synthetic heat transfer oils are used in many HTF applications like plastic and synthetic material fibre production, with temperatures of up to +400° C to be sealed. Conventional pumps were operated by auxiliary cooling via cooling chambers – this is uneconomical and technically problematic at the same time (lime deposit / “insulation” of cooling chamber).

Using the CHETRA tandem safety seal style 770 it was possible, for the first time, to abandon the auxiliary cooling of the pump. More than 1000 applications all over the world are proof of CHETRA’s successful seal system.