Tetra Marks 25 Years Responding to the Needs of Combined Cycle Plant Owners

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We have solutions to your HRSG, Boiler and Power Piping Problems

World map 2016Tetra Engineering Group, Inc. has assisted the owners of natural gas-fired combined cycle plants with effective remedies to pressure part thermal performance and reliability issues since 1993.  This includes some of the following 'firsts' for Tetra:

1993

First HRSG Assessment

1996

First  Reliability Assessment - Standard HRSG OEM Design

1998

First FAC Assessment for HRSG Tube Failures at Cogen

First High Energy Piping Inspection Plan

1999

First HRSG Two-Shift Cycling Assessment

2000

First HRSG Warranty Inspection

Third Party Review of Alternate TEG Distribution Grids

First HRSG Water Chemistry Training Seminar

2001

1st HRSG Cost of Cycling Assessment

First CCGT High Energy Piping RCFA

First HRSG Purge Time Assessment

First Fuel Gas-Steam Pipe RCFA

2002

1st HP ECON Tube RCFA

First Bowed RH Tube Evaluation

1st Ed., HRSG Tube Failure Diagnostic Guide

 RH Tube RCFA -  Fleet of Standard HRSG Design

Third Party Review of HRSG Harp Weld Quality

HRSG Design Review for Owner

2003

1st Piping Stress Analysis - HRSG RH Piping

Field Support following CRH Waterhammer Event

First CCGT Pipe Support Inspection

1st Ed., HUG O&M Manual

1st 3D Knowledge Management System

2004

1st  Review of Attemeprator Spray Control Logic

First Hot Reheat Drainpot RCFA

First Evaluation of High Energy Steam Drain Capacity

HRSG Baseline - North Africa

PipeVue 1.0 - First KMS for Piping

2005

HRSG and Steam Plant FFS - 10 Year Program

HRSG T23 Failure and Weld Quality

First Vertical Gas Path HRSG Tube RCFA

First Cost of Cycling Assessment

1st Ed., HRSG Inspection Planning Guide

2006

1st Evaluation - Changed Main Steam Temperature

First HRSG RCFA Projects - Various Clients in Mexico

HRSG Component Reliability Database

1st HRSG EOH Assessment

2007

1st NFPA 85 Improved Purge Time Evaluation

Third Party RCFA - Need for Chemical Cleaning

First Grade 91 Inspection Plan & Field Inspections

Engineering Review of Replacement Deaerator Design

2008

HRSG Thermal Design Tool: PPSD - Various Projects

Design and Installation of Improved RH Header Restraint

First Onsite Water Treatment Program Upgrade

First HRSG Hot Spot Warranty Project - Ireland

2009

1st FFS for Bulged CRH Piping Damage 

Field Support - Main Steam Stop Valve Damage

First ACC Inspection and Thermal Performance Evaluation

First LP ECON Header RCFA - Middle East

2010

1st CPS Piping Program - New ASME Requirements

First Deaerator Inspection and Condition Assessment

First FFS for Localized Thinning of FW Piping

First Casing Hot Spot Repair with Pumpable Insulation

2011

1st ACC Inspection and Condition Assessment

Thermal Evaluation of RH Lower Link to Manifold Cracking

Seawater Contamination during Commissioning - Middle East

P91 Hot Reheat Lateral Inspection and RCFA

2012

1st CFD Analysis of Perforated Plate in HRSG Duct

Third Party Engineering Review of OEM Re-Design of LP Evaporator

HRSG Damage and Remaining Life following Seawater Contamination

2013

1st HRSG Warranty Inspection - Peru

Long Term Third Party Witness - Offshore HRSG Fabrication

1st P91 Risk Assessment & Inspection Plan - IWPP Plant

2014

1st Benson Boiler HRSG Warranty Inspections

HRSG Outlet Manifold Creep-Fatigue RCFA

Main Steam Piping RCFA

PipeVue 2.0 - Released for Various Projects

Thermal Modeling - Prudhoe Bay Glycol Heating System

HRSG Vibration Study - Belgium

Tetra Engineering Middle East Opened - Dubai, UAE

2015

1st Fleet-Wide HRSG Health Check Assessment

Survey of Industry 'Rust' Release Experiences after Startup

Engineering Design and Purchase Spec. for Alteration to HRH Lateral

1st UT Linear Phased Array Inspection in Mexico

2016

3rd Edition, HRSG Tube Failure Diagnostic Guide

HRSG Beyond Design Lifetime Condition Assessment

Stress Analysis and Site Support  for Alteration of HRH Lateral

NFPA-85 Purge Compliance after Alteration - SCGT

Duct Burner RCFA

2017

1st CPS Piping Program - Canada

Engineering Study of HRSG Pre-Heat System for CO Emissions Control

First Condition Assessment for Once-Through SG - LM6000 Plant

Engineering Spec. for HRH Attemperator Upgrade

2018

First Fleet-Wide CPS (High Energy) Piping Program

15 Year Re-Evaluation of HRSG Cycling Assessment

.....

Our thanks to our clients for their patronage over all these years.  

Peter S. Jackson, P.E.
President
TETRA ENGINEERING GROUP, INC.
+1 (860) 651-4622
 
James W. Malloy
Principal Engineer
Tetra Engineering Europe
+33 (0)4 92 96 92 54
 

Tetra In Action #12, July 2018

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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.


Boiler Preservation Engineering

OEM or industry guidelines for Boiler or HRSG waterside and gas-side preservation (or “layup”) are useful but typically don’t go further than general advice on the different available options (wet vs. dry etc.).  The difficulty is in moving from the general to the specific for a given plant. 

Tetra can define viable preservation options and help you choose an optimal strategy from among these that fits your budget and operational constraints. 

If desired, Tetra will then develop a detailed engineering specification for your preservation system. 

For more information about the service click here.

Steam Turbine


Technical Tidbits from the Tetra 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.

Mark in Drum

Senior Engineer Mark Taylor from Tetra’s European office enjoying some quality Steam Drum time during a recent HRSG inspection campaign.

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

 

 

2018 CPS Piping Services for CCGT Plants

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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

Modern CPS Piping Programs have evolved from historical high energy piping (HEP) programs to address a host of CCGT-specific issues including: Grade 91 issues, turbine bypass and inter-stage attemperator piping thermal shock/quench and spray valve degradation, long term creep damage, flow accelerated corrosion damage to susceptible feedwater piping (spray supply, blowdown lines and HRSG interconnecting piping.) 

Some of the newest CCGT have as many as 4 desuperheater stations with dual HRH bypass and CRH bypass providing improved steam temperature control. These programs usually include the feedwater piping as well as LP Steam piping (which operates below the creep range) and auxiliary steam piping - if present. Stress analysis results and field walkdowns continue to be key elements of programs, but the focus today is on degradation specific inspection plans that go beyond the scope of radiant plant programs from the '80s which were geared to address the important needs of coal plant operators. Properly designed and constructed CCGT operate at conditions and stresses generally well below the corresponding values for radiant plants.  However, two-shift cycling, merchant operations, 'chasing' renewables in markets dominated by wind and solar and long layups in cold weather climates can all result in early in life damage. 

Tetra world

Root Cause Failure Analysis of CPS Piping, including interconnecting piping (for example, inter-stage attemperator piping), Grade 91 piping and carbon steel fittings and pipe sections has been a common request from our CCGT clients.  

Fitness-for-Service evaluations using the ASME FFS-1/API-579 Rev. 2 methods provide effective means to determine whether a degraded component can remain in service until a longer outage is scheduled or if immediate repair, replacement or derating is required to maintain safe and reliable operation.

For more information on CPS Piping Programs, Field NDT Services or other CPS Piping related evaluations including Pipe Stress Analysis, contact:

Europe/Middle East/Africa/Asia: Andreas Fabricius at +33 (0)4 92 96 92 54 or at This email address is being protected from spambots. You need JavaScript enabled to view it.  

North/Central/South America: Peter Jackson at +1 860 651-4622 ext. 103 or at This email address is being protected from spambots. You need JavaScript enabled to view it.

 

Tetra In Action #11 - December, 2017

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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

 


Recent Projects: RCA of Repeat Tube Failures

TETRA Engineering was recently contacted by a client in Asia concerning Superheater tube failures in a supercritical coal boiler and asked to conduct a Root Cause Analysis (RCA).  A senior Tetra engineer visited the plant to gather information on the history of the failures and relevant data to be used for the RCA.  The failures were occurring in one specific region of the boiler (in one instance not long after tube replacement), on hanger tubes concentrated at the right-hand side of the unit.  Observations made on the tube failures included

  • The gas temperature at the right-hand side of the boiler was often over 100°C higher than the left
  • Metallurgical analysis of failed samples revealed fish-mouth failures caused by short term overheating
  • Failures occured following increase from 60% load to full load

RCA

After the elimination of other possibilities, it was hypothesized that the tubes were overheating due to temporary loss of steam flow which, when combined with the higher gas temperatures at the RHS, led to a concentration of failures.  Following this, the operating conditions were modelled using Power Plant Simulator and Designer (PPSD) to evaluate the necessary conditions for these failures to occur.

It was shown that the under low loads, the steam may have been condensing at the bottom of the investigated hanger tubes due to low flue gas temperatures in this region (it entered the tubes only just above saturation).  This led to blockage of the tube and restricted steam flow.  When load increases, and gas temperatures increase, the tubes overheat – particularly at the RHS due to flue gas temperature skew.

For more information about this project contact Fraser Davidson at This email address is being protected from spambots. You need JavaScript enabled to view it. . For more information about our Failure Analysis Services contact James Malloy at This email address is being protected from spambots. You need JavaScript enabled to view it. .

  


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..  

 

Tetra In Action #10 - November, 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. 

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 #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. 

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..  

 

How do GT Upgrades Impact your HRSG?

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OEM upgrade packages to gas turbines (GT) can significantly improve performance, operational flexibility and increase outage intervals. In combined cycle power plants, the impact of these upgrades should also be considered for the HRSG where the design was based on the original GT performance.

Common changes that impact the HRSG include :

  • More efficient operation of the GT at lower load (lower flue gas mass flows, higher temperatures)
  • Modifications to exhaust gas profiles at various loads
  • Duct burner firing characteristics
  • Changes to fuel fired
  • Increased outage intervals

 

Tetra Engineering can assess the impact of changes in GT performance on the HRSG and help optimise O&M activities.

See here for our short flyer or contact us for more information:

For US, Central- and South America: This email address is being protected from spambots. You need JavaScript enabled to view it.

For Europe/Middle East/Asia: This email address is being protected from spambots. You need JavaScript enabled to view it.

 

 

 

Packaged Boiler Services

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Engineering Services for Package Boiler Troubleshooting 

IMG 0229

Tetra Engineering Group, Inc. can provide complete engineering support for procurement, operations, maintenance and troubleshooting of your package boiler in auxiliary or primary steam service.
 
Our capabilities include:
  • Thermal Performance Assessment and Analysis for any type of pre-heating, process or other application. Both static and dynamic analysis of steam production, temperatures, circulation flows and gas side conditions can be evaluated.
  • Steam velocities and other impacts of lower pressure options as well as use of alternative working fluids such as glycol are easily handled.
  • Pressure part integrity and failure analysis for boiler tubes, piping and drums.
  • Water Chemistry and Steam Quality Support.
  • FGR, Fan and Ducting Design, Maintenance and Troubleshooting.
  • Field Inspection of Boiler Fire-side and Water-side conditions.

Contact Tetra today if you are interested in these Package Boiler Engineering Services.

For more information, please contact

North and South America:

David Moelling, +1 860 651-4622, This email address is being protected from spambots. You need JavaScript enabled to view it.

Europe/Africa/Middle East/Asia: 

James Malloy, +33 4 02060254, This email address is being protected from spambots. You need JavaScript enabled to view it.

Thermal Plant Simulation

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 Advanced Software for Power Plant Simulation 

Power plant

How a High Fidelity Thermal Plant Simulation Package Can Help Your
Engineering Group Keep Your Plants at Peak Productivity.

 

Tetra Engineering Group, Inc. and KED, GmbH have partnered to offer the industry's most advanced steam plant simulation package for your central office engineering team. 

The Power Plant Simulator and Designer system (PPSD) is a complete high fidelity plant and steam generator offering. Used by many OEM’s worldwide it is also a complete and independent system for plant operators and owners.

No matter what kind of thermal plant you operate, Conventional Coal (sub and supercritical), CFB Coal, IGCC Coal, Gas Turbine Combined Cycle, MSW boilers, package gas and oil systems, ORC heat recovery systems and solar hybrids, PPSD can give you the answers you need. Not only the overall heat balance and performance, but component performance details as well for both steady state and dynamic plant operation. This allows your staff to support levels of troubleshooting and modification engineering at lower cost and faster turnaround.

The PPSD system can also be easily integrated into any kind of “Digital” plant system or information cloud you might have.

Tetra Engineering has over 25 years of experience in supporting all types of thermal plants during design, development, operation and uprating. We use PPSD regularly in all phases of plant evaluation.

As a licensed representative of KED for PPSD as well as a key development partner we provide complete support to operating plant PPSD users. We can offer a complete package to get you up and running quickly. This includes: 

  • Corporate PPSD Licenses and Support (including upgrades and technical support). 
  • Initial Training of system users Development of initial plant models for your system (anywhere from one to several models for complete design and monitoring). 
  • Development of Operational Packages for the plant models to perform any number of key tasks such as performance trending, component life tracking, generation of unmonitored alarms using “hidden” data. 
  • Integration with “Digital plant systems”.

Contact Tetra today if you are interested in having your own in-house capability for this type ofanalysis. We can provide you with details of PPSD licensing, training and technical support.


For information contact:

North and South America:

David Moelling, +1 860 217 9331, This email address is being protected from spambots. You need JavaScript enabled to view it.

Europe/Africa/Middle East/Asia: 

James Malloy, +33 4 02060254, This email address is being protected from spambots. You need JavaScript enabled to view it.

 

About Us

Established in 1988, 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.

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Our Locations

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