Refining Community Logo

New Tools of Evaluation, Local Failure Index, Changing the way of Analyzing Laser Mapping

Presented By

Christian Ljungmann - Tricom Scan

Ezequiel Justiniano - Tricom Scan

Roberto Bello - Intevep PDVSA


Tricom Scan Coke Drum Software Viewer
New Tools for the Industry – A Step Forward

The Past
For more than a decade, Tricom Scan has been inspecting coke drums around the world, listening and realizing the needs of the customers, while investing in R&D constantly.

At the beginning, the software given to the refineries to visualize the laser mappings of their coke drums were non-compatible, closed software, which could only open files from the provider in question, and later on, also compare mappings, but only their own.

Those Visualizers were also focused only on the size criteria of the bulges and left aside many other important variables to be analyzed.

This motivated us to develop new tools, with a clear objective shared with our clients: to constantly improve the quality and precision of the analysis instruments.

That was the cornerstone from where new standards have risen and been incorporated by the industry.

The Challenges
During the development of our software, we faced several programming, engineering and mathematical challenges, which were successfully solved.

We wanted to move forward with a service that provided more accurate data and a greater number of measurement points, but for that, we had to develop algorithms for interpolation, filtering and analysis much more powerful than those that existed at that time.

We were wondering:

These were some of the challenges to be solved and so we started to work out on new tools that allow us a better understanding of the behavior of the coke drums.

Better Technology, Better Data
The first step was to develop a better hardware, since what existed at that time was heavy, slow, and inaccurate. The laser technology of our competition surveys 9500 measurement points per second, an amount which we deemed insufficient, hence we started using our own device which delivers more than 200000 measurement points per second.

We also started using 3d laser technology, avoiding the use of a moving part (the cutting tool) to create the z axis of the point cloud, and we were the first company to scan the domes and cones more than 10 years ago too.

This led to another challenge, the development of a more powerful software that would be able to handle the large amount of precise data we were collecting (millions of points: the Tricom Scan Analyzer Viewer; an integral software for the analysis of coke drums.

courtesy of Tricom Scan SRL

courtesy of Tricom Scan SRL - 1

New Tools for our Clients

Bulge Tool
As the best way to facilitate the client locate the deformations found in the color mapping, the Bulge tool was introduced. This tool not only shows the location of the most prominent bulging on the drum, but also depicts its nominal values; an upgrade was later categorizing them according to its severity.

courtesy of Tricom Scan SRL - 2

Bulging evolution analysis across time – Side by Side and Overlay comparison
Another key aspect for a client is to analyze the evolution of a coke drum’s condition, so a comparison between different scans performed in several periods of times was imperative, hence the Side by Side multi comparative tool and the Overlay Comparison were introduced.

With the multi comparative tool, introduced two years ago and later updated, both scans are viewed simultaneously. Just by placing the mouse in where ever section of the color mapping, we can clearly observe both horizontal and vertical cuts throughout the whole drum of both mappings with the respectively growth values.

courtesy of Tricom Scan SRL - 3

Beneficial to the client was also the addition of the Overlay Comparison, which is the friendliest tool of clearly showing how the bulges evolve across different periods of time. By super positioning both mappings of different date, the client can scroll from one to the other, easily observing how the bulging changes along.

Courtesy of Tricom Scan SRL - 4

Visual Inspection meets Laser Scanning
The Image Analysis and the Laser Mapping reports were presented separately in the past, with the typical inconveniences associated with it. As a way of developing a more friendly tool, our software now merges both into one, allowing the client to choose which area of the drum to visualize directly from the color mapping.

Thermal Mapping
A fundamental aspect to interpret production efficiency is to analyze the temperature cycles of the DCU. Following our policy of continuous innovation in our services, we move forward with the introduction of the Thermal Mapping, a tool that helps understand the thermal behavior of the coke drums in whichever period of time the client wants to select

The Final Evolution

And for this year we will present the biggest breakthrough in laser mapping.

An analysis tool that goes beyond what is known in Laser Mappings, adding a new focus on the problem of Coke Drums.

A tool that allows us to relate two different approaches, the geometric and the mechanical.


Tricom Scan has been in the forefront of Coke Drum inspections and analysis for the past 10 years, evolving constantly and introducing new standards to the industry in various aspects referring to inspections of Coke Drums, from better accuracy in laser technology to better definition in the visual inspections, from light and efficient teams and equipment to year after year improving its own software, from “opening” the data so to encourage competition and comparisons to, now, introducing a new standard in how to conduct a proper and outright strain analysis; the core component has been the same: to help our customers, the refineries, take care of their DCU the best way possible.

Many things changed in this last decade because of Tricom Scan involvement in the market, like now it’s standard to analyze the complete drum, with its dome and cone as well, but when we started doing so, it wasn’t the case, and so on. But… why a new strain analysis?

The main reason is always the same: to improve our clients satisfaction, in other words, to give them new tools that might help them make better decisions towards their drums, but where did it come from is another story…

The Need of a New Standard

Coke drums are pressure vessels that normally are composed of a wider Cr-Mo alloy steel base wall (shell), in the range of the 40mm, and an aprox. 3mm martensitic stainless steel cladding that covers the whole inner wall of the shell.

When Tricom Scan started performing mechanical analysis of the coke drums utilizing data obtained from our laser mappings, we realized, among other things, that the industry was taking into account only the base wall, disregarding the effect of the cladding. We accepted what was (and still is!) the classical approach and conducted the typical stress analysis. The problem arose when, after comparing multiple stress reports done with how the drums actually were and its evolutions, the results tended to be partial and, many times, did not even match with the facts of reality. Indicators, such as the Bulge Stress Factor (BSF), were heavily influenced by the out-of- roundness of the drums, misguiding the critical areas of the drums to be prioritized in order to avoid potential cracking. We concluded that this indicator exposed sensibility to geometric distortions like bulges, out-of-roundness and weld misalignment alike and in the same extent, and was only effective in new, or slightly used, vessels; failing to provide proper results for the assessment of drums with excessive out-of-roundness and bulging.

The Challenge

Hence, we decided to go further from what the industry was saying and started to develop new software to evaluate both the base material of the shell and the cladding, respectively and separately. The obtained outcomes were, predictably, different for the cladding and the shell, because the components are different, with different physical and mechanical behaviors, most importantly, different thermal behaviors. Analyzing both parts together as one it’s a conceptual mistake and it cannot even be interpreted as an approximation.

Another claim that Tricom Scan confronted was the heavily spread statement in the industry that said that “it is impossible to fully apply the API 579/ ASME FFS-1 Level 3 Strain Assessment in a Coke Drum” since it’s not specifically for coke drums and, moreover, requires the use of the equivalent plastic strain calculations. However, through the development of new analysis methods, Tricom Scan was able to develop an Index of strain analysis that, not only is the most accurate and exhaustive for the refinery’s needs, but also complies with the code in an unprecedented way. We believe that the standards are to be applied, nevertheless the increment in our costs of R&D, and that’s why the LFI is the only index in the industry to do so, unlike the BSF (Bulge Stress Factor) or the PSI (Plastic Strain Index), which fail to do.

Advantages of the Local Failure Index, or LFI

The Local Failure Index provides a tool with a higher sensitivity to bulges and a lower sensitivity to other geometric distortion effects in order to predict bulging induced cracking, in full compliance with API 579 / ASME FFS-1.

This critical failure indicator ranges from 0.0 to 1.0, with permanent strain limits according to the industry standards (API579/ASMEFFS-1), and:

– Its magnitude is representative of the most important aspect of bulging: the sharpness of a bulge

– It also allows the refineries to obtain a recommended number of cycles for their next Laser Scan Inspection (laser mapping frequency),

– It provides information about critical zones that need further inspection or reparation; whether to plan a local crack inspection and/or to identify the need of a weld overlay repair

– It quantifies the probability of crack development induced locally by fatigue around bulges, as well as around misaligned welded unions (high LFI values are an accurate indicator of potential failure areas)

LFI constitute a useful decision tool for improving the operational parameters. Also, a time evolution of the LFI will indicate the areas most prone to failure. Several operational and maintenance decisions could be made as LFI shows increasing values.

It is important to remark that LFI is not a method which detects, identifies, measures or characterizes cracks in a direct manner, since laser-scanned data cannot resolve the geometry of an existing crack. This method identifies the zones where crack existence or formation is likely to occur, and quantifies its probability. Further localized inspection with specific crack search methods is always recommended for the highest values of LFI.

LFI vs older indicators

As stated before, the LFI is the only index that takes into account both the filtering of geometric distortion effects (the BSF does not) as well as following the standard with Equivalent Plastic Strain calculations (that the PSI fails to do). Nevertheless, here’s a diagram summarizing the LFI vs other indicators:

courtesy of Tricom Scan SRL - 5

Case Studies

Here are some examples of the accuracy of the LFI as a strain analysis indicator, in contrast to other ones. In the LFI figure t’s clear how the out-of-roundness, for example, doesn’t mislead the outcome of the drum’s most critical areas of concern for the refinery; as opposed of other indicators where the outcome is clearly tainted. (The graphs are from the same Drum)

courtesy of Tricom Scan SRL - 6

courtesy of Tricom Scan SRL - 7

A Contribution to the Industry

As stated at the beginning, Tricom Scan has been evolving constantly, year after year, and developing new tools for the inspection and analysis of the DCUs for the sole purpose of assisting our clients, in particular, and the industry, in general.

As of now, we haven’t advertised many of our additions, nevertheless changing common practices for the whole DCU refining industry: no more “close” data, no more large teams and equipment where the refinery had to take care of customs diligences, no more low resolution videos, no more the impossibility of comparing data from different years or different contractors, no more lasers where the z axis had to be developed while lowering the equipment with the cutting tool instead of having 3D native technology, no more 1 point every square inch…

The Industry’s Standards and Codes help refineries in how to take care of their assets, conducting actions in a safer way, reducing waste, improving the overall efficiency while assuring quality at the same time. Many common practices in the inspection side have evolved due to Tricom Scan contributions, such as the analysis and scanning of the whole internal drum’s wall (cone and dome included), smaller and more efficient teams and equipment, higher accuracy and better resolution, open data, 3D technology and software developments. Now, is in the field of an Integral Strain Analysis that we want to leave our mark, developing and implementing calculus to meet the standard criteria never done before, a new standard.



Refining Community