At the Frankfurt site of the leading European company NOBIAN, EBNER carried out the repair of one of two identical heat exchangers in a production plant in spring 2026. In close cooperation with the customer, a tailored repair concept was developed. The repair became necessary due to a leakage at the gas inlet nozzle of the carbon steel/rubber-lined heat exchanger.

The heat exchanger, equipped with floating graphite tubes, was only partially retubed. The existing V-flange was removed, and the shell joint at the gas inlet nozzle was stripped of its rubber lining. After welding in a new V-flange and preparing the metal surface in accordance with rubber-lining requirements, this section of the heat exchanger was relined by a specialized contractor.

During this process, the entire heat exchanger—still partially fitted with tubes—was vulcanized in an autoclave at 110°C and 3,5 bar pressure for a duration of 8 hours. Fortunately, the existing seals inside the heat exchanger withstood this additional thermal and pressure exposure.

Subsequently, the removed graphite tubes were replaced with new ones, and the heat exchanger was prepared for recommissioning. The advantage of this approach was that not all tubes had to be replaced, resulting in a significant cost reduction due to the partial retubing.