OTC Leak Search & Repair

The problem

The GT 26 low pressure and high pressure Once Through Coolers (OTC) reduce the temperature of the Gas Turbine’s cooling air systems.  This is through a heat exchange between the GT cooling air and water (steam) from the Water Steam Cycle.  Over operational time the OTC’s can develop leaks between the air and water sides.

This leak of water into the cooling air system detrimentally  increases demin water consumption and has the potential to impact the cooling air ratios.  It can also lead to increased levels of corrosion in the system.

The solution

There is a simple repair on an OTC with a leak.  The affected OTC needs to be opened, the leak located, then plugged and the OTC closed again. This requires a team including a lead engineer, pipe fitters, coded welders and specialist support of NDT and Heat Treatment services.

Salko was engaged to carry out such a search and repair recently for a GT26 client on behalf of the OEM completing a larger inspection of the power plant.

The outcome

The OEM was looking for a simple turnkey service for the search and repair of the OTC.  This started with the OEM providing the relevant technical instruction and introducing our team to the GT26 client.  From there the Salko team was able to develop the quality plan, and agree this with the GT26 client.

The Salko team then liaises with the onsite OEM team and GT26 client as required –  with minimal input needed from either,  whilst ensuring that they are kept up to date with the progress and findings. Requesting their involvement in the completion of the quality plan as the work progresses.

Following the technical instruction and quality plan the team then proceeded to cut open the relevant OTC, conduct the leak search, identify and confirm the leaking tube(s).  Salko then report and record to the OEM and GT26 client before the leak is then plugged.  The required prep is applied to the cut end caps of the OTC which is then NDT‘d before re-welding. Once the prep NDT is confirmed, without findings, the cap ends are set into their original position for installation. As the cap ends are welded the required NDT and heat treatment is completed.

A final report is then produced with the completed Quality Plan, Welding quality pack, NDT reports and Heat Treatment charts. Along with any applicable material certificates.  This is passed to the OEM for forwarding to the GT26 client.

The aim is to provide a simple solution for the client who engages us, minimal input, search and repair completed safely, efficiently and to the right quality.  Then handed back with a comprehensive record of the works.

Get in touch

Get in touch with our team at Salko UK

For a clear, honest appraisal of your next project. Just give us a call to get started on 01430 431977