What is the common failure mecahnism for a Deaerator Tank, what is the recommended inspection method, and how often should they be inspected?

Answered by: Kevin Kissig

 

 

A Deaerator (DA) Tank is a pressure vessel found in boiler systems which removes gases (mainly oxygen) from condensate and make-up water.  They generally consist of a water storage section and a deaerating/heating section.  These tanks are typically made of welded carbon steel, and the residual stress of the welds coupled with the mechanical stress of operation makes them susceptible to weld cracking.  Left undetected, these weld cracks can lead to catastrophic failures.  In addition to the damage caused to the tank itself, catastrophic failures of a DA Tank often turn the tank into a projectile as steam and water are released from the failure resulting in additional destruction to facilities, equipment, and personnel.

 

Preventative measures are a good starting point when considering a maintenance program for DA Tanks.  When purchasing a DA Tank, while it is generally not required, insist that all welds be stress relieved (post-weld heat treatment) in order to reduce the residual weld stress that often leads to cracking.  All welds should be inspected for cracking by qualified technicians utilizing wet fluorescent magnetic particle inspection (WFMT) within five years of being placed in service, and then on a five-year cycle.  This will help ensure that any cracking caused by operating stress can be detected and repaired prior to a catastrophic failure.

 

While there are monetary and time costs associated with timely inspection and repair schedules, these costs are minimal when considering the costs associated with a single unscheduled repair resulting from a catastrophic failure.  It is very important that these thanks be properly maintained from both a reliability and safety consideration.  For more information, please refer to the National Board of Boiler and Pressure Vessel Inspectors at www.nationalboard.org











I am new to the NDE industry. How long does it typically take to become certified in each method?

Answered by: David Kissig

In order to properly answer this question, it is important to know the type of industry and country the work will be performed in.  A list of several certification programs are listed below to provide a short insight into the many programs available.

• SNT-TC-1A - The American Society of Nondestructive Testing (ASNT) - This set of guidelines, first published in 1966, is call the Recommended Practice No. SNT-TC-1A.  This document established the levels of qualifications based upon a combination of education, training, experience, and qualification examinations.
• CP-189 - The American Society of Nondestructive Testing (ASNT) - This standard was approved in 1989.  The intent was to produce a document that provided strict requirements rather than guidelines.  ASNT obtained ANSI (American National Standards Institute) accreditation to process this document and recognized ASNT CP-189 as a national standard thus becoming ANSI/ASNT CP-189.
• NAS-410 - The National Aerospace Standard - In the 1990's MIL-STD-410E was replaced by NAS-410 for aerospace and defense related military or government contracts.  The current revision (rev. 3) is considered technically equivalent to the European Standard EN4179.
• ISO 9712 - International Standard for Nondestructive Testing Personnel Qualification and Certification - ISO 9712 was published in 1992 as an international standard that would be recognized by participating nations.  This document is similar to SNT-TC-1A with an additional requirement that personnel be certified by a nationally recognized certification program and required more training than does SNT-TC-1A.
• CGSB-48.9712 - Natural Resources Canada (NRCan) - This certification program is utilized in Canada and is managed by a nation-wide independent NDT certification agency.  The purpose of this program is to provide an unbiased Canada-wide NDT certification of personnel.

As you can see, there are many different personnel qualification and certification programs currently in use around the world.  The ASNT SNT-TC-1A employer-based certification has been widely accepted throughout the United States and is the program First Quality Solutions uses.  It is this program that we will outline to provide our answer to your question.



SNT-TC-1A has been prepared to establish guidelines for the qualification and certification of NDT personnel whose specific jobs require appropriate knowledge of the technical principles underlying the nondestructive tests they perform, witness, monitor, or evaluate.  Two definitions that are important to this discussion are: Qualification and Certification.

• Qualification - Defined by ASNT as; Demonstrated skill, demonstrated knowledge, documented training, and documented experience required for personnel to properly perform the duties of a specific job.
• Certification - Written testimony of qualification.

Once the qualification requirements have been met, the employer then certifies the individual in the particular method.  Prior to certification of NDT personnel the employer shall establish a written practice for the control and administration of NDE personnel training, examination, and certification.  The length of time to become certified will vary based on the method and the requirements of training, experience and testing.  Another concern is whether a company will certify to level I and then to level II, or directly to level II.  The training hours remain the same for both approaches, however, the requirements for level I and level II are combined to certify directly to level II. 

The  recommended practice provides the required hours of experience and training for each method.  The requirements vary from 210 experience hours and 24 training hours to obtain visual inspection certification with a high school education to 1470 experience hours and 68 training hours for thermography. 

The question of how long does it take depends on many factors and needs to be addressed with one's employer, with the requirements of each industry, codes, and standards taken into account.  As you can see there are many variables to consider, but I hope this gives you a general idea of the commitment needed to become a part of this exciting and rewarding industry.  A more  specific answer can be provided by asking about a single NDT method, please email us if you would like more details.





What would you consider First Quality Solutions' primary or signature inspection type?

Answered by: Kevin Kissig

 

 

There is no one type of inspection that we perform more than any other type; we perform magnetic particle inspections on pumps and gears on an almost daily basis, and several times each year we routinely inspect headers, piping, fans and tanks, but if there is an inspection we've really perfected over the years, it would be boiler waterwall ultrasonic thickness inspections.

 

 





Waterwall inspections are generally the first inspection we perform during a power plant maintenance outage, and the results usually precede waterwall panel replacements.  Therefore, the faster we can provide the results of this inspection, the faster our customers can begin panel replacements.  As such, we've always looked for ways to improve the efficiency of this inspection. 

 

Over the years, we've upgraded our equipment and experimented with different transducer types to provide the best results possible.  We've also done extensive tests on different couplant mediums and application methods.  We've transitioned from manually applied grease (messy and timely to clean), to mechanically applied oil-based couplants (prone to equipment failures and also requires post-inspection cleaning), and finally began using a manually applied water-based couplant that simply evaporates off the tubes after the inspection (no clean-up time required).

 

Our reports have also evolved over the years to provide the most detailed and well-organized information possible.  Details and formatting have been adjusted over time, and the final reports are an invaluable tool for our customers to make informed decision at the moment as well as for planning future repair areas.

 

   

 

2002 Waterwall Survey (Upper) & 2012 Waterwall Survey (Lower)

 

 

Finally, our inspection team is extremely experienced in regards to this inspection.  The waterwall inspection team has been working together for years, and each member of the team is well-aware of his or her responsibilities and duties during a boiler waterwall inspection.  The team performs as a well-oiled machine, and what used to take several days in prep, inspection, and reporting time, has been reduced to a couple of shifts.  It is an inspection that is extremely familiar to us and one that we are exceptional at performing, and it is an inspection that we continue to improve on every time we perform it.







I enjoyed the history of liquid penetrant, can you explain the origins of magnetic-particle (MT) inspection?

Answered by: Dane Ross

Most people in the non-destructive testing field know what magnetic particle inspection is, but few know where it originated from.  For those of you who don't know what magnetic particle inspection is, it is a non-destructive testing process used to detect surface and slight subsurface discontinuities in ferrous materials, which are materials easily susceptible to magnetism.  A part made out of such a material is magnetized and magnetic particles are applied to the part.  Any discontinuities on or close to the surface of the part will create a break in the magnetic field, which will attract the magnetic particles.  An area of accumulated particles form an indication, and reveal a discontinuity.  Sounds exciting, doesn't it?  But the real question is where did all of this start?  It's not like on the 8th day God created the Magnaflux yoke...so how did magnetic particle inspection evolve to where it is today?

This is where the real intrigue starts because the first observations of magnetism date back more than 2500 years and this is where the history of our modern magnetic particle inspection begins.  The Chinese observed that a "lodestone" or a naturally magnetized piece of magnetite had the power to attract pieces of iron to it.  Around 1088 A.D. they found that if a needle that had been magnetized by stroking it across a lodestone was suspended it would point north and south.  It could therefore be used to improve the accuracy of navigation, thus inventing the compass.  Fast forward to 1868 when it was observed that a compass needle jumped when passed over a crack in a magnetized cannon barrel, and could therefore be used to inspect for cracks.  In the 1930's, by observing iron filings on magnetized parts, patterns in the filings allowed for the first visualization of the magnetic field or "magnetic lines of flux."  These patterns were able to reveal discontinuities on the surface of the parts, thus creating magnetic particle inspection.








 

From that point forward, ways to improve on these principles have been developed.  Now AC or DC current can be used to establish a magnetic field in parts being inspected.  Improvements in how to properly identify discontinuities have evolved from compass needles and iron filings to detection media such as iron powders and iron particles suspended in various liquids.  Color coding these types of media also improved visibility and contrasting on test parts to make identification of discontinuities easier.  The introduction of florescent iron particles and UV light increased sensitivity and further advanced these principles, thus creating another variable in aiding to identify discontinuities.  Although it has been thousands of years since the first observations of magnetism, the basic principles remain the same but every year brings new innovations in the ever evolving field of non-destructive testing.

 

Dry Magnetic Particle Inspection

 

Wet Florescent Magnetic Particle Inspection

 



















Can you briefly describe the origins of liquid penetant (PT) inspection?

Answered by: Michael C. Schantz

The history of liquid penetrant testing can be traced back to the “oil and whiting” method. From the late 1800’s until the 1940’s, this technique was commonly used by railroad companies for finding cracks on steel locomotive parts such as rods, axles, crank pins, etc.   The advent of magnetic particle inspection in the 1940’s proved the “oil & whiting” method to be unreliable.  Until that time the “penetrant” that was used was typically a heavy lubricating oil diluted with kerosene.  The imprecise nature of the “penetrant” solutions, coupled with a lack of set procedures resulted in too many variables to provide consistency, and magnetic particle inspection was considered a more reliable alternative for testing magnetic iron and steels.

 

                The advent of World War II brought a new challenge to the inspection world when the extensive use of non-magnetic materials such as aluminum, magnesium and stainless steels in the aircraft industry.  At the time, radiography and magnetic particle testing was the only truly non-destructive methods available. Radiography was reliable for finding internal flaws in castings and forgings but was much less reliable for finding surface discontinuities. A new method had to be developed.

                Many methods were tested, but proved to be impractical or unreliable until Robert C. Switzer of Switzer Brothers, Inc. (now the Day-Glo Corp. of Cleveland) began working with colored dyes, in particular fluorescents, to locate defects in materials. He was successful in creating a method using fluorescent dyes and a black light which provided a high contrast on the part being tested. In February 1942 an exclusive license was given to the Magaflux Corp. to develop and perfect the method. By July 1942 Magnaflux introduced “Zyglo” the first commercially available product for liquid penetrant testing. Seventy years later, through numerous advancements in techniques and materials, fluorescent liquid penetrant inspection with Zyglo is still a consistently reliable and trusted inspection method that we utilize on a daily basis.

 



 

Welcome to the FQS Blog!

 

 

At First Quality Solutions, we get to work in a number of unique and interesting industries, and we're exposed to a wide range of challenges and opportunities.  As a result, our customers rely on us for advise and insights on everything from different inspection methods and techniques to failure mechanisms and common practices.  We spend a lot of time as a company conferring with each other regarding our own expereinces, as well as researching topics and questions for our customers.

 

The purpose of this blog is to share the insights we provide to many of our customers in the hopes that others with the same questions may find these entries interesting, informative, and hopefully entertaining.  We plan to post new entries at least twice each week, so please check back often for new posts. 

 

We welcome everyone to comment on posts, provide additional insights, or ask new questions.  We would like this blog to become an ongoing forum for sharing thoughts, questions, or concerns on many different topics and inspection disciplines.  We're currently working on entries for a number of common questions, so check back soon, and by all means...enjoy!

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When clients look to you for a quality product or service, and your employees deserve nothing less than a fully operational workplace...

There’s only one choice… First Quality Solutions!

For nearly a decade, First Quality Solutions has performed NDE inspection services for structural integrity, reliability, and safety in an extensive range of industries, specializing in turbines and boilers, pressure piping and vessels, pumps, and gears.

Our services include traditional non-destructive test methods such as magnetic particle, liquid penetrant, visual and CWI services, as well as technology-based methods such as ultrasonics, phased array, thermal imaging, and X-Ray fluorescent analysis.

Upon prompt & thorough completion of your inspection, we issue an unbiased report detailing all of our findings. If defects are detected, or compliance has not been met, we welcome the opportunity to guide you through a comprehensive repairs process.


Contact First Quality Solutions today.  It’s More Than an Inspection…It’s Peace of Mind!