Tetra In Action #6 - February, 2017

on .

Assuring HRSG and Boiler Pressure Part Quality

June, 2017 - Managing Boiler & Steam Cycle Pressure Part Integrity

This training course is primarily intended for experienced O&M staff working in thermal power and process plants, but could also be of interest to corporate engineering and management staff. The objective is to give attendees a comprehensive view of the strategy, actions and considerations involved in effectively managing and thereby assuring the integrity of piping, tubing and vessels that form the pressure boundary to steam or water process fluid. A range of topics relating to the design, inspection and repair of relevant components are treated using a combination of theory and numerous practical examples. The examples are all based on actual project cases encountered by Tetra Engineering staff at plants around the world.  The full course syllabus can be found here.

To register and secure your spot today contact Christine Vallon or call our European office at +33 (0)4 92 96 92 54.

For our full range of courses see our 2017 schedule at http://tetra-eng.com/training


Covered Piping System Maintenance Programme

Since 2007 the ASME B31.1 Power Piping Code has included Chapter VII, establishing mandatory requirements for Operation and Maintenance. The key elements of this program are discussed here, and require that Operators outline a detailed maintenance plan for their Covered Piping Systems (CPSs).  The Code also requires that operators perform regular Condition Assessments of their CPS ensuring that relevant degradation mechanisms are being covered.

Tetra provides the following services to Owners and Operators of Combined Cycle and Thermal Power Plants to help meet the ASME requirements and thereby assure the long-term integrity of their piping systems:

  • Technical Support For Implementing a B31.1 Compliant CPS Maintenance Programme
  • Grade 91 and CSEF Integrity Assessment
  • Piping Degradation Risk Assessments
  • Piping Inspection and Condition Assessments

Tetra has developed PipeVue 2.0, a unique and powerful software tool to manage the data from design, inspections and repairs of piping in an integral manner, by linking all this information to a 3-D model of plant piping and making it accessible through a simple click of the mouse


Tetra Engineering in the Guinness World Records!

Tetra Engineering's own Andreas Fabricius and cycling partner Axel Carion are currently past the half-way mark of their World Record attempt to cross the South American continent North to South by bicycle.  Scott Napier's current record stands at 58 days.  See this photo below of Andreas crossing the Argentinian border at 4400m elevation (14400ft) days ago.  You can follow their journey (here) and track their progress.  Their journey is raising money for Pompiers Sans Frontières (Firefighters Without Borders - see website), providing crucial resources to underfunded firefighters in South America. 

Tetra Engineering is sponsoring their effort and wishes them good luck! 

 

Tetra in Action #5 - October, 2016

on .

Assuring HRSG and Boiler Pressure Part Quality

Remember -Certification Does Not Always Equal Quality!

HRSGs and power boilers are built by assembling large numbers of components, mostly by welding.  Design choices in optimizing heat transfer against overall cost lead to configurations that aim to minimize the number of welds per square meter of heat transfer surface.  In addition, fabrication of the modules is frequently subcontracted by the OEM for manufacture in regions where manpower is cheaper.  The OEM becomes in effect an integrator of components built by others.  How can Product Quality for pressure parts be assured in that context?

Under the ASME Power Boiler Construction Code, the approach is to initially to certify a manufacturer by approving a suitable QC program, including the qualification of welding procedures and welders themselves.  Going forward, Quality would then be assured by the manufacturer’s adherence to their approved program and by the presence of the ASME Authorized Inspector on site. 

The Authorized Inspector has a number of compulsory checks that must be made in person but, in practice, a large portion of the welding continues without any further follow-up, except where the Code requires NDE.  If the approved QC program becomes a box-ticking exercise – for example when schedule constraints take priority – weld quality can decline resulting in unrepaired defects.  The problem for the Purchaser is to determine whether the manufacturer’s QC program can be trusted to guarantee a quality product.

Tetra’s experience is that product delivered by a number of OEM’s has on frequent occasions displayed unacceptable weld quality, despite the OEM and/or subcontracting fabricator having a valid quality certification in place.  The cause is systemic management focus on schedule and cost, with quality given a lower priority.  Many rejectable weld defects are not visible from the outside and only infrequently will the module fail the field hydro tests (although this has occurred).  The main concern is that a large population of weld defects present in a set of tube modules will affect pressure part longevity, particularly if the plant is in cyclic operation.
To assist clients in their pressure part procurement process, Tetra Engineering performs:

  • Project Vendor and Product Sourcing Quality Assessments
  • Expert and Enhanced Factory Fabrication Surveillance (see following example)
  • Warranty Risk Evaluation

A Recent Case History

Weld Inclusion

During a recent Tetra project thousands of still images of tube to header welds were taken using a borescope in several HRSGs at a plant site just after commissioning.  The images were thereafter reviewed independently by at least two engineers.  The tube to header welds were found to be characterised by a general lack of good workmanship with numerous defects or flaws apparent.  The initial inspection of one set of upper SH headers yielded 20 tubes that had weld defects serious enough to require repair.  It should be noted that repair can be difficult because of poor access.  Similar results were found in SH modules from the other units.

 

  Results on Header
Category Count %
Accept 100 53%
Substandard 68 36%
Fail/Repair 20 11%
Total 188 100%
Results: Borescope Inspection Campaign of 188 tubes 

For more information about this service send us an email (This email address is being protected from spambots. You need JavaScript enabled to view it. ).


A Successful First Boiler & Steam Cycle Knowledge Workshop in Dubai!

Tetra Engineering held its first steam Boiler & Steam Cycle Knowledge Workshop at the Media One Hotel in Dubai.  Five of the seven workshop topics were presented by a team of four instructors from our company, the other two were presented by external collaborating partners: Mr. Jamie Pollock of Mettek Ltd. and Messrs. Tord Forslund & Leif Andersson from CCI Valves. Attendees could sign up for topics “à la carte”, these ranged from how to meet B.31 requirements for piping inspections to particular problem issues such as waterside deposition or creep. See here for more information.

HRSG Workshop


HRSG Inspection Planning Guide Snapshots

One of the first applications of the borescope was for inspecting steam turbine rotor discontinuities in the 1920s.  Today a wide variety of commercial borescopes and videoprobes can be used for access within HRSG components.  These include both flexible and rigid borescopes and a variety of videoprobes and end effectors.   Mirror or prism attachments can be used to get right angle views of tubes or pipe connections.   Access can be via hand-holes or other penetrations.
Flexible video inspection probes employ high-resolution camera at the probe tip to capture detailed color inspection footage.   Interchangeable lenses bring subjects both near and far into sharp focus.  Variable-intensity fiber optic illumination floods hidden targets with cool, white light.  Knobs on the handset control the tip’s up/down and left/right articulation.

 Borescope

Figure: Typical Flexible Fiberscope (Courtesy, InterTest, Inc.)

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

Tetra Article in Power Magazine

on .

A recent article published in Power Magazine explains the continuing importance of Condition Assessments of HRSGs in optimising Operational and Capital Expenditure. See this link for more details. 

HRSG Tube Failure Guide, 3rd Ed.

on .

Pre-Publication Discount Available on HRSG Tube Failure Guide, 3rd Ed. 

The latest updated edition of Tetra Engineering's HRSG Tube Failure Diagnostic Guide will be published August 15, 2016.

Thousands of combined cycle professionals are familiar with Tetra's HRSG Tube Failure Diagnostic Guide; first published during the 'bubble' in construction in the early 2000s.

The latest edition includes additional material on waterside deposits, creep fatigue cracking, fireside corrosion and others.  Many new photos and illustrations now make it easier to use.

Each copy of the Guide is offered at $195 USD after August 15.  The special pre-publication price is $165 USD.  Inquire for volume discounts.  Shipping is in addition to the per copy charge.

For more information please contact Natalie Vasa at This email address is being protected from spambots. You need JavaScript enabled to view it. or by phone at +1 860 651-4622

 

Tetra In Action #4 - July, 2016

on .

Come see us at the PowerGen Asia conference in Seoul!

Chief Engineer David Moelling of Tetra Engineering is presenting the Tetra/R&R Consult paper Root Cause Failure Analysis of Superheater Tubes Using Computational Fluid Dynamics Simulations at the PowerGen conference in Seoul on the 20th of September at 2PM. 

“As the electricity market has evolved with the addition of renewables to the generation mix, Heat Recovery Steam Generators (HRSG) that were originally designed for base load conditions are now frequently forced to operate in a cycling and/or low-load regime. This can lead to front end tube-to-header fatigue, creep or creep-fatigue failures, often induced by GT flow imbalances causing locally-elevated tube temperatures and/or bending stresses on joints due to large temperature differences between tube rows. This paper focuses on the use of Computational Fluid Dynamics (CFD) as a tool to analyze the root cause of Superheater tube failures. Exhaust gas flow profiles were analyzed for base load and low load conditions for a vertical Heat Recovery Steam Generator (HRSG). The plant suffered from tube failures that could be shown to be directly related to low-load (and start-up) exhaust gas flow patterns. The contribution of CFD to identifying these conditions that lead to the failures are presented and mechanisms to reduce future risk of failure, such as addition of flow-conditioning devices, are investigated and presented."

More details about the Tetra presentation and the conference can be found here and 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 send us an This email address is being protected from spambots. You need JavaScript enabled to view it..


HRSG Inspection Planning Guide Snapshots

The following HRSG locations are affected by external corrosion and oxidation:

  • External Corrosion (Evaporators, Economizers, Feedwater Preheaters)
  • Acid Dew Point Corrosion (Feedwater Pre-Heaters)
  • Oxidation on High Temperature Tubes (Superheaters, Reheaters)

External corrosion, as the name implies, occurs on the exterior surface of steel components in the HRSG. It affects both pressure parts and structural elements and requires the presence of corrosive agents to drive the reaction with the metal.  The most common agents are oxygen and water.  When shutdown these are present in the air and when running are present as components in the gas stream.  

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 #3 - June, 2016

on .

Dubai: September, 2016 - Boiler & Steam Cycle Knowledge Workshops

Tetra Engineering announces a series of targeted workshops to provide thermal and process plant O&M engineers, managers and operators with a working knowledge in several aspects of the boiler and steam process technology. Drawing on our field experience working at power and process plants throughout the world, the objective is to provide attendees with clear instruction on the operator actions and design issues that can impact reliability, efficiency and operating life.  The programme comprises a set of focused, half-day training modules intended to leave attendees with a practical working knowledge on these issues.  A number of outside experts will join Tetra's senior staff in delivering the workshops.

The course syllabus can be found here.


Newly Published Technical Papers by Tetra Engineering Collaborators

An engineering consultant needs to stay up to date in his knowledge and try to contribute to furthering that knowledge.   Therefore, the staff engineers at Tetra don’t just work on commercial projects, they also take the time to do research and development on a variety of boiler and steam cycle engineering issues.  This is actively encouraged by the company as it only increases the level of skill that our collaborators can bring to bear for solving a given client’s problem. 

Over the years Tetra engineers have published many papers and attended numerous technical conferences and forums.   In the past 2 years the following papers were presented or published with collaborators from the various Tetra offices as authors or co-authors:

  1. Technical Paper and Presentation:  Impact of Startup Purge Credit on Combined Cycle Plant Operation. Authors: Andreas Fabricius, Mark Taylor, Dave Moelling (all Tetra Engineering); Proceedings of the ASME 2015 Power and Energy Conversion Conference PowerEnergy 2015, June 28-July 2, 2015, San Diego, California; (Link)
  2. Technical Presentation:  Chemical Cleaning of the HRSG Waterside: When, Where and How? James Malloy (Tetra Engineering) and Steve Wynne (Chemical Cleaning Consultants), European HRSG Forum, Munich May 11-13 2015. (Link)
  3. Technical Paper:  Premature Grade 91 failures - Worldwide Plant Operational Experiences, Authors: Andreas Fabricius and Dr. Peter Jackson (both Tetra Engineering); Journal of Engineering Failure Analysis, August 2016, Volume 66, Pages 398-406. (Link)
  4. Technical Paper and Presentation: Understanding Variations in Flow-Accelerated Corrosion Wear Rates in HRSG Evaporator Tubes,  Authors: James Malloy and Mark Taylor (Tetra Engineering) Jan Rusaas (R&R Consult, Denmark); Conference on Flow Accelerated Corrosion 24-27 May, 2016; Lille, France. (Link)
  5. Technical Article:  Covered Piping Systems O&M Programs for CCGT Plants, Authors:  Robert Rosario and Dr. Peter Jackson, Power Magazine, April 2016, (Link)

An additional paper by Tetra collaborators Dave Moelling and Andreas Fabricius (and third co-author Jan Rusaas of R&R Consult) has been accepted for presentation at the upcoming Powergen Asia (Tuesday Sept 20th, see details here):  Root Cause Failure Analysis of Superheater Tubes Using Computational Fluid Dynamics Simulations.


Technical Tidbits from Tetra’s HRSG Inspection Planning Guide

HRSG Structures are exposed to weather, hot turbine exhaust gases, steam and water leaks and emissions control chemicals.   Deadweight, wind, thermal and seismic stresses also are applied to the HRSG.  These components are typically inspected on an opportunistic basis, for example during annual statutory inspections by the insurance company’s boiler inspector or during scheduled work on other major components such as the GT.  

Early HRSGs had frequent problems with the duct and casing/liners.  HRSG OEMs have responded to these problems with improved rials, improved bolting patterns and related improvements to designs of other components such as duct burners that have been responsible for damage to liners in certain configurations.

Casing liner plates are often found damaged in the transition duct at the exit of the gas turbine.  This is particularly common in ducts with abrupt geometry changes such as 90° angles in the duct or other sharp angled transitions.  Another common location for liner damage…

Casing Liner Plate Washer Nut Missing

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. )

Tetra In Action - June, 2016

on .

France: June, 2016 - Effective Operation of the HRSG Course

This seminar is primarily intended for O&M staff at all levels of experience working in combined cycle power plants, but should also be of interest to engineers and managers involved in new project development. The course gives attendees a comprehensive yet in-depth survey of a broad range of topics relating to the design, operation and maintenance of the HRSG and associated steam cycle systems.  Drawing on our field experience working at power plants throughout the world, the objective is to provide attendees with clear instruction on the operator actions and design issues that impact HRSG reliability, efficiency and operating life.

The course syllabus can be found here.


Recent Projects: Site Works Survey SE Asia

TETRA Engineering was engaged by a European client to perform a site works assessment at a Southeast Asian power plant construction site. Work had been delayed for months due to disagreements among two parties involved in the project regarding scope of work, responsibility and scheduling issues.
A Tetra engineer visited the site to meet with key personnel from the parties and to inspect the current state of the works. The results of the survey revealed

  • Lack of communication between both parties
  • Delays caused by one party in part of their scope of activity significantly delayed the other party’s progress in the project, causing a large financial loss and deterioration of equipment due to excessive exposure to elements.
  • Discrepancies in the original scope of work caused added delays in the schedule and increasing the level of discord between the two parties
  • As a “neutral” observer, the Tetra engineer was able to identify contradictions in the respective positions of the parties based on actual observations made on site

Corrosion on incomplete boiler assembly Civil Works

Left: Corrosion Due To Inadequate Preservation; Right: Civil Works

 


Technical Tidbits from Tetra’s HRSG Inspection Planning Guide

Analysis of deposits found in the HRSG is a common and very useful way for determining what is occurring on both the waterside and gas side.  Waterside deposits found in the drum are analyzed to determine chemical and elemental composition.  The presence of certain elements such as chlorine might indicate that there is or was a problem with contamination of the boiler water.  Analysis of gas side deposits such as those found on the cold end tubes can identify the various compounds present and their disposition in the deposits.  Excessive cold end deposition results when unit design does not match actual fuel characteristics or from mistuned process conditions.  The deposits are often corrosive and can lead to premature tube failures as well as loss HRSG or boiler performance.

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. )

Tetra In Action - May, 2016

on .

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 in Power Magazine here


Dubai: September, 2016 - Boiler & Steam Cycle Knowledge Workshops

Tetra Engineering announces a series of targeted workshops to provide thermal and process plant O&M engineers, managers and operators with a working knowledge in several aspects of the boiler and steam process technology. Drawing on our field experience working at power and process plants throughout the world, the objective is to provide attendees with clear instruction on the operator actions and design issues that can impact reliability, efficiency and operating life.  The programme comprises a set of focused, half-day training modules intended to leave attendees with a practical working knowledge on these issues.  A number of outside experts will join Tetra's senior staff in delivering the workshops.
The course syllabus can be found here.


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.

DrumInspector
Figure 1 : 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. )

2016 Training Schedule Announced!

on .

Tetra Engineering has announced its schedule for HRSG & Combined Cycle training events in 2016.  This year we will be hosting training courses in Utah and Connecticut, USA, as well as in France and a new event in Dubai, UAE.  See our training page for more details.

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.

Links

Our Locations

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