Inspectioneering Journal

Interview with John Nyholt - BP NDE Specialist

By Greg Alvarado, Chief Editor at Inspectioneering. This article appears in the September/October 2004 issue of Inspectioneering Journal.

Exactly two years ago, in the September/October 2002 Issue, an interview with John Nyholt appeared in the “IJ”. New ground will be covered in this interchange. John has primary responsibility for NDE consulting and troubleshooting for BP around the world in the exploration and production, refining, and chemical business streams. We at the IJ thought it might be valuable to spend some time chatting about his background, challenges he has faced recently and what he feels are some of the biggest challenges ahead for the Inspectioneering® community. Within this we will discuss the NDE technology development cycle and applications of NDE in our industries. We hope you enjoy the interview.


John, it is always interesting to hear about how someone got into the inspection profession. Will you tell our readers a little about your background and how you became a worldwide resource, providing NDE direction for BP, often at crucial times?

John Nyholt (JN): After earning my AAS degree in Non-destructive Testing from Moraine Valley College, I started my NDE career working at the McDonnell Douglas Corporation (now Boeing) in St. Louis, Mo. I worked for their fighter aircraft division from 1982 to 1991. Work at the defense industry level can be both interesting and innovative. In 1991, I joined the Amoco Oil Company (acquired by BP in 1999) at the Whiting, Indiana refinery. In 1994, I moved to the Amoco Research Center in Naperville, IL as an NDE specialist for the corporation. My main office is now located at the BP Central Engineering offices at the Houston-Westlake complex. I also have a joint-venture NDE Applications Lab at the San Jacinto College Central Campus. I teach NDE college courses when I have time, However I don’t get to spend as much time in Houston as I would like.

In the earlier years of my current position, I created course content for and delivered internal training for routine NDE methods used within the corporation and handled special NDE applications as they arose. Some of these tasks were daunting, but were usually successful with the help of some excellent mentors in our central engineering team. Many are engineers at the top of their fields in metallurgy, corrosion, equipment design, and project management. We worked well collectively and were willing to answer late-night phone calls. This helped me tremendously in understanding the behavior, morphology, and anticipated locations of damage mechanisms. This type of understanding is very important in the effective development and application of NDE.

In-house training is now limited to the occasional NDE overview/ refresher course for BP inspectors and engineers or NDE vendor workshops that provide tech-transfer to vendors who deliver our application lab technology to the field. However, my current priorities have been less and less around the routine day-to day consulting, and more on the development and delivery of long-term, high risk NDE projects. As BP continues to push the exploration and production envelope into deeper waters, NDE of our floating platforms, riser pipes, and ocean floor equipment becomes more complex and more integral to other advanced subsea technologies. External NDE consultants, research institutions, and service providers are heavily involved, and their new technologies are carefully taken into consideration in “one-chance to get it right” situations. However, in my opinion, as successful NDE application is often one that is as least “advanced” as possible. The confidence level and successful use of many recommended NDE methods or applications rests within the current stage of their lifecycle.

What are the stages of NDE as you see them in our industries?

JN: I use three primary life-cycle categories, each with their own risk and cost/benefit rank: R&D stage, emerging, and mature technologies.

The first stage is “R&D” (research and development, of course). At inception, NDE researchers postulate a fairly generalized problem/solution to a need across, or specific to an industry problem. In a simplified description of this stage, NDE feasibility of a new or revised technology stems from laboratory experiments intended to bind its capabilities and limitations under controlled conditions. Many technologies spend 3 to 5 years in this stage. Characteristics of R&D stage NDE include:

  • Limited availability through NDE research Institutions
  • Attractive solutions to difficult problems (high payback)
  • Little or no track record (high risk)
  • High cost (need to recoup R&D funding in 1-3 years)
  • Field applications are experimental

Examples include next-generation radiographic detector arrays and microwave NDE. The second stage is “Emerging” technology. At this stage, technology is commercially available with ongoing field trials and understanding by the end-user. Characteristics of Emerging NDE include:

  • Recent commercial availability
  • Single, or a highly limited number of service providers
  • High cost (Service vendor needs to recoup heavy investment)
  • System operators have had some learning but need plant experience

Examples of Emerging NDE are ultrasonic phased array, guided wave ultrasonics, EMATS, SLOFEC, pulsed eddy current and other special applications.

The third life-cycle category is the “Mature” stage. At this stage the advantages and limitations of the technology have been either correctly or incorrectly established, utilization and market value have been defined by the end-user, competition and lower costs have set in, and derivative techniques within the technology have begun to evolve. Characteristics of a Mature NDE technology include:

  • Advantages and limitations are assumed
  • Recognized by Code, standards, and specifications
  • Operators and equipment are readily available, and the technology can be applied with limited operator error
  • Lower cost

Consideration of these three stages of NDE technology during their use could benefit all levels of the NDE industry: research institutions, service providers, and end-users.

In the R&D stage, end-users must understand and accept the risks. Field implementation may be voluntary, with the appropriate time, funding, job planning and data validation in place, or it may be reactive to a critical problem at hand. With the latter often being detrimental to all parties, it would be best to have appropriate industry assessments made in advance. However, we all know how this may be short-circuited by aggressive sales to recoup investment, early release of the technology into the “emerging” stage, over selling of capabilities, and pressure from end-users to have the technology perform at a “mature” stage level, often with little or no data validation because it may cost more than the inspection itself. This, coupled with the lack of standardized field validation protocols promotes inconsistent conclusions between end-users. Service providers and researchers subsequently struggle with survival of their technology, which in turn raises the bar on decisions to innovate and invest further in the technology in order to get to the next stages, or may even effect decisions to engage in other areas of NDE R&D.

R&D stage technology should be mentored by the end user under in terms of identified “essential variables”, which are defined as all physical and operational parameters that may affect the test in each setting. This may include materials of construction, geometry, temperature, test environment, and availability of qualified technicians. Researchers, service providers, and end- users would also need to admit that the learning curve for R&D level technology may be substantial, and ultimately bourn by the end-user on his/her assets. This is why it is often best to measure and mentor R&D level technology by industry consortia consisting of research institutions, end-users, and service providers.

The previous discussion greatly affects the “emerging” stage or the technology. Premature commercialization and inconsistent representations of the technology may cause polarized opinions and erratic utilization. This often makes my job difficult within BP, and I’m sure that plant inspection personnel have had similar experiences.

The success or failure of the “R&D” and “emerging” stages ultimately affect the start or occurrence of the “mature” stage. Poor performance of the first two stages could either kill an application that had some merit, forward a technology that has little or no merit, or cause a valuable technology to languish in a perpetual “emerging” stage, seeing limited investment, utilization, and a continuously high cost. Many of us have seen this in the areas of acoustic emission and advanced ultrasonic techniques such as long range guided wave ultrasonics.

What is an example of a new application you find especially valuable?

JN: Flexible matt arrays of multi-plexed pulsed eddy current (PEC) probes. They have a lift-off limitation of less than or equal to 2" (50.8 mm) and maximum temperature range of up to 750 F (398.9 C). We are currently using them to monitor areas for potential erosion corrosion.

How do you view current electromagnetic technologies, for example EMATS and PEC?

JN: As screening tools, they are only part of an overall on-line inspection strategy. Their value is usually dependent on the use of other technologies, what we are looking for, and associated risks. It’s difficult to quantify the fitness for service or estimated remaining life of operating assets by the sole use of volumetric techniques.

What are some examples of current challenges?

JN: Well one application would be SCR’s (stationary catenary risers) in deep water installations in the Gulf of Mexico.

These risers are in depths greater than 6500' (1,981 meters) of water, pipe diameters down to 8" (203 mm), and have 2" (51 mm) of wall thickness due to the high pressure and temperature of deep water production fields. Applying external NDE techniques by ROV (remotely operated vehicles) is difficult as 3 1/2" (89 mm) of externally applied fusion bonded epoxy insulates the riser. We have various geometries such as 3D bends, and of course there is 4000 PSI (276 bar) of pressure. A mix of externally deployed NDE techniques, permanently installed sensors, and advanced intelligent pigs are currently under development. The list of potential damage mechanisms and detection thresholds are challenging; 5% general wall loss, 2-1 aspect ratio pitting 2 mm (0.080") deep X 4 mm wide (0.160"), SCC at the base of pits, and cracking 1 mm (0.040") deep X 10 mm (0.400") long.

We also have a concern of paraffin wax filling the pits and of how this may affect some NDE methods. Our target scan speed is 1 meter per second. The tool must navigate varying nominal diameters from 8" (203 mm) to 10" (254 mm) to 8".

What options are you considering for inspection, with what concerns?

JN: Creeping UT waves with a leading surface eddy current sensor carrier in the pig train is one possibility. Another potential pig technology is multiple-mode transducers in a spinning mirror setting similar to IRIS tube inspection technology. One potential drawback we may encounter is slower scanning speed due to lower velocities encountered in oil versus water.

On another topic, how do you feel about global and/or volumetric scanning techniques to find CUI (corrosion under insulation).

JN: We have limited use of them until the appropriate “emerging” technology assessments have been made We have joined a couple of industry JIP’s for that purpose, For now, we have more confidence in RT in conventional or filmless configurations. Some are in-motion techniques. Our financial cost criterion is no more than $30 US per liner foot. Beyond that the technology is cost prohibitive as you could strip insulation and visually inspect.

What is the highest equipment surface temperature equipment at which you have found CUI?

JN: 800 F (427 C). We now have an automated ultrasonic scanner that can handle this temperature for the safety of the operator and reliability of the data. Continuous contact transducers and couplants are now commercially available.

What is the highest temperature at which you have seen acceptable crack detection and sizing?

JN: I recall an application in a resid hydrotreater unit at 750F (399 C). As this was in a tight spot on an elbow, we built a wand to hold the UT transducer assembly with automatic couplant feed. An innovative service provider later developed an automated scanner. We used high temperature aviation oil as a couplant. A 6" (152 mm) quench line into an 18" (457 mm) elbow had caused localized thermal fatigue cracking. The elbow was stainless steel 2" (51 mm) thick.

We felt confident, by trials, that we could detect cracks as shallow as 1 mm (0.040"). We used an ID creeping wave and shear wave, simultaneously. The creeping wave and high angle L wave were used in tandem to confirm surface connection of the crack.

The transducers had surface wedges made of materials with high temperature resistance. Only a couple of manufacturers are capable of making transducers to handle this temperature.

Thanks for all of that detail, John. It is very important. Any other applications you would like to mention in parting?

JN: Only that we are looking at the use of phased arrays for flange face corrosion detection and measurement. A conventional UT application developed a couple of years ago may be a good candidate for UT-PA. I’m hoping for improved detection of HF-Alky flange face corrosion.

John, thank you very much for your time and sharing. I am sure our readers will find your insight both practical and valuable and we look forward to hearing from you again.


Comments and Discussion

There are no comments yet.

Add a Comment

Please log in or register to participate in comments and discussions.

Inspectioneering Journal

Explore over 20 years of articles written by our team of subject matter experts.

Company Directory

Find relevant products, services, and technologies.

Training Solutions

Improve your skills in key mechanical integrity subjects.

Case Studies

Learn from the experience of others in the industry.


Inspectioneering's index of mechanical integrity topics – built by you.

Industry News

Stay up-to-date with the latest inspection and asset integrity management news.


Read short articles and insights authored by industry experts.

Expert Interviews

Inspectioneering's archive of interviews with industry subject matter experts.

Event Calendar

Find upcoming conferences, training sessions, online events, and more.


Downloadable eBooks, Asset Intelligence Reports, checklists, white papers, and more.

Videos & Webinars

Watch educational and informative videos directly related to your profession.


Commonly used asset integrity management and inspection acronyms.