Tetra In Action #9 - October, 2017

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2018 Spring/Summer Training Schedule Announced

Tetra Engineering announces the 2018 spring/summer training schedule! Join us in Deer Park Utah, USA in May or Sophia-Antipolis, France in June for HRSG & Combined Cycle training. See our training page for more details. 



HRSG Inspections - The Key to Reliability

At Combined Cycle Power Plants the Heat Recovery Steam Generator (HRSG) is an easily-overlooked, but key component, providing steam to the steam turbine and to attached process steam hosts.  While base-loaded HRSGs tend to be the most reliable - cycled or two-shifted plants suffering from accelerated damage - the importance of allocating sufficient resources to maintenance of the HRSG is often only realised in hindsight.   Even a simple visual HRSG Inspection during an outage can provide useful information about the how the HRSG is aging and what maintenance should be planned to ensure ongoing reliability.  Many have experienced the sudden drop in reliability that comes when a neglected HRSG begans having tube failures in one area, causing frequent shutdowns that later aggravate other incipient problems that could have been avoided by simple performing a Visual Inspection, and taking remedial action early on.  Tetra Engineering has been performing HRSG Inspections for over fifteen years - over 650 Inspections to date! - and provides an integrated service that supports Owners and Operators throughout the full HRSG life-cycle.  In addition to the HRSG Inspections we also perform HRSG Condition Assessments, in which we review not only the present condition of the HRSG Unit but also how historical operation has affected its integrity. 

As part of its HRSG Life Management services, Tetra also draws on its unique skill set, including extensive field experience and engineering analysis, to assess the HRSG's susceptibility to certain damage mechanisms (e.g. Fatigue, Creep, FAC, Corrosion) and produced customised HRSG Inspection Plans. Those plans can be used by inspectors and NDT-teams during plant outages to target HRSG Inspections where damage is most likely to be found.

For more information on HRSG Inspections and Inspection Planning, see our Field Services page or contact This email address is being protected from spambots. You need JavaScript enabled to view it. for USA or This email address is being protected from spambots. You need JavaScript enabled to view it. for Europe/Middle East/Asia.


Technical Tidbits from the HRSG Inspection Planning Guide

Thermal overstress is generally associated with the high temperature sections of the HRSG (HP Superheater and Reheater).  Flow starvation in a tube relative to its neighbors results in the tube metal temperature approaching the gas temperature.  In that case, tube-to-tube differential temperatures may exceed 500°F (260°C).  The enormous thermal stress that results exceed material yield stress and cause permanent bowing…  

bowed tubes

If you are interested in the full version of the HRSG Inspection Planning Guide (2nd edition) contact Ms Christine Vallon at This email address is being protected from spambots. You need JavaScript enabled to view it..  


About Us

Established in 1989, Tetra Engineering has more than 25 years experience providing solutions to the power industry. We specialize in solutions for HRSGs, conventional boilers & steam-cycle balance of plant.


Our Locations

Offices in: Connecticut, USA; Nice, France; Dubai, UAE.