News

Tetra In Action #12, July 2018

Managing the Power Piping in CCGT Plants

Risk of failure and attendant personnel safety concerns are always present when operating highly-pressurized systems.  Over the years, the occurrence of catastrophic events has driven improvements in construction codes and updated recommendations for O&M practices.  As part of this trend, expanded requirements for operations and maintenance (O&M) were recently added to the ASME Code for Power Piping—ASME B31.1.   The “Chapter VII Operation and Maintenance” was created in 2007 to prescribe guidelines that promoted early failure detection and overall safety. This was a fundamental change to the scope of B31.1, which up until then was strictly a design code; going forward, it now serves a dual purpose…

Read the full story by our colleague Robert Rosario, published online in Power Magazine here.

Read more: Tetra In Action #12, July 2018

2018 CPS Piping Services for CCGT Plants

2018 CPS Piping Services for CCGT Plants

Tetra Engineering Group, Inc. has assisted many owners of natural gas-fired combined cycle plants with the development of effective Covered Piping Systems (CPS) Programs, Inspection Plans, Pipe Stress Analysis and Field NDT since the ASME adopted the new Code requirements for piping O&M in Section B31.1 Chapter VII in 2007.

Tetra has developed such programs for CCGT owners in the US, Canada, Mexico and the Middle East.  They have been prepared for 'bubble' 2x1 design with F-class gas turbines as well as modern 1x1 fast-start units, plants with aeroderivative GTs and once-through steam generators as well as smaller units operated by municipal power companies, some of which are in cogeneration service. 

Based on the latest B31.1 requirements, the CPS Program Plan is tailored to meet your requirements especially regarding the scheduling of NDT inspections over multiple outages to distribute costs and meet outage budget constraints

Covered Piping systems O&M Programs for CCGT Plants

Read more: 2018 CPS Piping Services for CCGT Plants

Tetra In Action #10 - November, 2017

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. 

course

 


Recent Projects: Increasing HRSG Thermal Efficiency

The Power Plant Simulator & Designer (PPS&D) provides state-of-the-art capabilities for modeling and simulating the operation of nearly any type of thermal power plant. Originally developed by KED GmbH in Germany for use by boiler OEMs in their detailed design work, PPS&D has since been used by numerous clients worldwide for simulating the operation of many types of boilers and thermal power plants.

Using this powerful tool, Tetra can model power plants and use simulations to assess the impact of modifications done to equipment, or operating conditions. Recently, Tetra used this method to evaluate the impact of lowering the approach temperature of the LP Economiser for one of our clients. In addition to ensuring safe operations, by looking at potential steaming in the economizer and the risk of Flow-Accelerated Corrosion (FAC), it was found that the overall HRSG efficiency could be increased by 1% leading to an increase in power output for the steam turbine of 1MW. The overall efficiency increase is estimated to lead to an increase in revenue by over 400.000 EURO/year.

ppsd

For more information about our Simulation Services 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/Africa/Middle East/Asia.

  


Technical Tidbits from the HRSG Inspection Planning Guide

The inspection of drums is a key element in determining the general condition of the waterside pressure boundary of the HRSG components and the quality of the water treatment program.  They are a “window” on what the inside of the water-filled or steam and water-filled tubes and headers in the various pressure circuits (HP, IP or LP) might look like.  Basic inspection is visual, yet often complemented by UT, and PT/MT examinations.One of the key items of interest is surface passivation.  The HP drum should typically have a dark grey adherent surface layer, characteristic of magnetite, below the maximum waterline.  Above the maximum water line there may be some light red coloration, indicating a mix of magnetite and hematite.  Yet surface color can deceive, drums with “abnormal” color may simply reflect a specific water chemistry and process condition history.  The experience of the inspector comes into play in these cases, to decide whether what is observed is indicative of a real problem or simply reflects a harmless difference.

drum

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..  

 

Tetra In Action #11 - December, 2017

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. Don't miss our Early-bird discounts! See our training page for more details. 

course

 

Read more: Tetra In Action #11 - December, 2017

Tetra In Action #9 - October, 2017

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. 

course

 


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..