pipeline pigging and integrity management conference

Pipeline Pigging and Integrity Management conference, Houston, TX. February 2020

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Tank Farm Pipeline Inspection Program Using Robotics

by Juan Martinez, Paul Laursen, Greg Herbstritt, and Todd McClellan Colonial Pipeline Company and Pipetel Technologies

Pipeline Pigging and Integrity Management Conference

Marriott Marquis Hotel, Houston, USA February 17-21, 2020

Organized by Clarion Technical Conferences and Great Southern Press

Pipeline Pigging and Integrity Management Conference, Houston, TX. February 2020

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Proceedings of the 2020 Pipeline Pigging and Integrity Management conference. Copyright ©2020 by Clarion Technical Conferences, Great Southern Press and the author(s).

All rights reserved. This document may not be reproduced in any form without permission from the copyright owners.


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Abstract Colonial Pipeline Company (Colonial) is developing a program to maintain the integrity of the traditionally unpiggable pipelines inside their tank farms. As part of this effort, Colonial is systematically implementing a program of pipeline inspections, to accurately rank, assess, and repair their tank lines. Colonial operates 14 tank farms across 10 states in the USA. Tank farm lines typically carry products including diesel fuel, kerosene, and gasoline. The tank lines in the tank farms are typically installed below grade, run between a tank and the facility manifold, and are not configured for traditional in-line inspection (ILI). When considering an optimal method to assess their integrity, not only is it paramount to choose an inspection method that yields comprehensive and accurate data, but also one that minimizes the amount of time required to complete the inspection and generate the corresponding reports. Since the development of the tank line inspection program in 2012, Colonial has evaluated several different inspection technologies. In 2015, Colonial utilized Pipetel’s Explorer ILI robot for pipeline inspection for the first time to inspect a 24-inch tank line in a tank farm. Since then, due to the high quality data results, additional tank lines ranging from 24 to 36 inches in diameter have been inspected using this technology. This paper will provide information on Colonial’s tank line integrity program and the operations and preparation required for conducting a robotic pipeline inspection at a tank farm. The authors will discuss the results obtained from robotic inline inspection including the accuracy of the data collected. Introduction Statistics show that facility releases are now generally occurring at a higher rate than those along pipeline right-of-ways. While the volumes associated with facility releases are generally small, the increasing number of occurrences contrasts with the liquids industry goal of zero incidents and zero loss of containment from petroleum pipelines and related facilities. An awareness of the frequency of releases and the zero target goal have generated an increased focus on facility integrity programs. At the same time, technology developments aimed at addressing difficult-to-inspect conditions at pipeline facilities have expanded substantially over the past decade. Pipeline operators are now applying a range of technologies for integrity assessments to address low-flow/low-stress pipelines, tank lines, drain lines, and other facility inter-connected piping. Due to the unique challenges and specific threats identified on tank line piping systems at Colonial, a standalone program was developed. A risk prioritization matrix was developed to identify tank lines that need to be assessed. The results of the risk prioritization matrix are continuously being evaluated and adjusted based on results of inspections completed. Since the program was first implemented, multiple assessment methods have been considered and tested. To date, the use of self-propelled robotic tools with Magnetic Flux Leakage (MFL) and deformation sensing have proven to be the most effective for the tank line application. Pipetel’s Explorer ILI tool has been used to inspect tank lines at Colonial since 2015. These self-propelled robots can enter and exit a pipe from a single point of entry and provide high-resolution, integrity data. The most significant challenge when using Pipetel’s technology is the amount of preparation work required to have the tank line ready for inspection and ensure a successful run. The pre-run preparation work includes:

(1) Emptying the line and isolating it from active piping and the tank,


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(2) Segmenting the tank line into 500 foot segments to facilitate high-pressure water blasting/cleaning,

(3) Cleaning the pipe with high pressure water (4) Installing new pipe where the tank line had been segmented (5) Installing temporary traps on each end of the line and pigging any water or residue out of

the line until no standing water or debris is present (6) Receiving and staging the robotic tool for three to four long and short runs

This paper focuses on Colonial’s experience inspecting tank lines. Tank Line Inspection Program Colonial is an interstate common carrier of refined liquid petroleum products. The company operates a 5,500 mile pipeline system of mainlines and stublines that originate in Texas and terminate in the New York harbor area. An essential part of Colonial’s system is a series of 14 tank farms located along the footprint of the mainline system. Maintaining the integrity of all the systems in these facilities not only helps Colonial approach the industry’s zero release goal, but also helps maintain pipeline operational flexibility. A product release from a tank line in one of Colonial’s tank farm facilities motivated the company to look closer at these piping systems and develop this system-wide program. The program objective is to assess and maintain the integrity of the tank lines to achieve the goal of zero tank line releases while maintaining operational flexibility. In 2012, a Colonial facility experienced a tank line leak. The leak occurred in a low elevation area of the line where water and debris had accumulated, resulting in an internal corrosion pit located at the 6 o’clock position. In response to the leak, the tank line was replaced and other tank lines in the facility were inspected. The results of the inspections showed that several tank lines exhibited internal corrosion pits in local low spots along the length of the tank line between the 5 o’clock and 7 o’clock positions at the bottom of the pipe. The information defining the potential trouble areas in each tank line prompted the company to perform a threat assessment of the tank lines in the system, make a determination if internal corrosion in the tank lines was a systemic threat, and develop a risk prioritization matrix to plan integrity assessments. Colonial’s tank lines range in diameter from 16- to 36-inches, and have varying wall thicknesses and material properties. The tank lines are sloped from the higher elevation tank downwards to the lower elevation manifold area. Operating pressures through the tank lines are substantially lower than mainline conditions, with typical operating pressures well below 20 percent of the pipe Specified Minimum Yield Strength (SMYS). Depending on the date of construction and the number of line crossings inside the facility, sag bends and flat spots may exist in these tanks lines, increasing the potential for water accumulation and debris build up. Additionally, the majority of the tank lines do not operate continuously like mainline systems and may remain idle for several days. Inactivity reduces the flushing of debris and water from the local low areas. Colonial’s risk prioritization matrix considers factors that may increase the likelihood of debris and water accumulating at low spots in the tank lines that may create a corrosive environment. Along with a significant data mining effort, interviews were held with personnel who had historical knowledge of the facilities to gather the data necessary to properly rank each tank line’s corrosion risk. The variables included in the prioritization matrix include:

(1) The potential of a tank line to trap debris and water; affected by factors such as tank line elevation profile, sag and over bends.


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(2) The time that the tank remains idle under normal operations. In order to account for the time that the tank remains idle, the tank operations database is used to account for how often delivery is made from each specific tank.

(3) The potential to flush the debris and water accumulated in the tank line; affected by factors such as diameter, product type and flow rates at which the line is operated, as well as the presence of water draw systems, their effectiveness and how often they are used.

(4) Year of construction also categorizes tank lines based upon years of service with corrosion potential.

Currently, tank lines are inspected preferably during the API 653 out of service inspection of the tank, although, some tanks may be taken out of service with the sole purpose of completing the tank line inspection. The risk matrix is periodically evaluated against available ILI results and adjustments are made by including new variables or excluding variables determined to be non-relevant. One of the most interesting adjustments made in the program has been lowering the ranking for all gasoline tank lines as those inspected to date have been found to be in good condition when compared to those in other product types. Different tool technologies have been considered for the inspection of tank lines at Colonial. Tank lines typically extend from a common manifold area to a tank. Unlike the mainline and stubline pipelines, tank lines are not equipped with launching and receiving traps for ILI tools. Alternative methods to ILI assessment, such as hydrostatic testing and direct assessment have been considered. The low operating pressures at which the tank lines are operated and the nature of the integrity threat of the tank lines make the use of hydrostatic testing impractical. Limitations on data available, such as detailed tank line profiles, make the use of External Corrosion Direct Assessment (ECDA) unfeasible in most cases. Due to Colonial’s tank farm configuration and operational needs, the best opportunity to inspect the lines is while the tank is out of service and the line is drained of product. Running an ultrasonic sensing tool becomes impractical due to the large volume of water that would be needed to clean the line and to run the tool. Tools that can be pushed through the line with air have also been tested, but speed excursions have resulted in degraded data and challenges to locate anomalies reported by the tool. The lengths of these tank lines, the number of bends, the space limitations, and difficulty of excavating several tool access points make the use of tethered tools very challenging. To date, the technology that best accommodates the tank line inspection program at Colonial are Pipetel’s robotic inspection tools. Pipetel’s Solution and Technology Pipetel has been operating a fleet of robotic inline inspection robots, known as Explorer ILI, for the inspection of pipelines since 2011. In addition, Pipetel began to inspect pipelines in terminals, facilities, and tank farms in 2015. These robots provide pipeline operators with high-resolution integrity data of their pipes. Many of the pipelines inspected had never been inspected by means of inline inspection. These pipelines were also limited to alternative assessment methods such as hydrostatic testing and direct assessment. Pipelines that cannot be inspected by conventional smart pigs are generally deemed “unpiggable” or “difficult to inspect.” These pipelines can be assessed by hydrostatic testing, direct assessment, or robotic inline inspection such as with Pipetel’s Explorer ILI. In the case of tank lines, the most common factors that render these lines difficult to inspect are the lack of launcher and receiver for conventional smart pigs, pipeline features that prohibit the passage of conventional smart pigs, and/or an insufficient pressure/flow rate for propulsion. Pipeline features that may prohibit the passage of conventional smart pigs commonly found in tank lines include: short radius elbows, mitered elbows, unbarred tees, back-to-back elbows, and vertical segments. Pipetel’s fleet of Explorer


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ILI robots overcome these challenges and inspect tank lines from 8- to 36-inches in diameter by crawling or self-propelling through these lines. The Explorer ILI robot fleet, powered by rechargeable batteries, can enter and exit a tank line from a single point of entry and does not require a tether for power nor data communication. Figure 1 illustrates Explorer ILI 20/26, which is compatible with 20-, 22-, 24-, and 26-inch diameter pipelines. From the point of entry, Explorer ILI robots can generally inspect 1,500- to 2,000-feet of pipe before returning to the same point for exit. This is illustrated in Figure 2. Alternatively, Pipetel’s Explorer ILI robots can inspect 2,500-feet of pipe from the point of entry to a different location for exit.

Figure 1: Explorer ILI 20/26 – A tetherless robot for inspection of unpiggable pipelines.

Figure 2: Explorer ILI enters and exits a pipe from an opening next to a tank.

In the example depicted in Figures 3 and 4, Pipetel’s tool propelled itself out of its tray and into the cleaned pipe and inspected 1,800-feet of 24-inch diameter pipe by entering the pipe from an opening next to the tank. Once Explorer ILI propelled its way to the end of the inspection at the manifold (Figure 5), Explorer ILI was driven back to the opening (Figure 6). To complete the assessment of the entire pipe, Explorer ILI re-entered the other side of the opened pipe and inspected the remaining pipe towards the tank until Explorer ILI reached the bottom of the tank (Figure 7). Once again,


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Explorer ILI was driven back to the opening before being removed from the pipe, completing the assessment of the entire tank pipe from the tank to the manifold. Explorer ILI inspects at a speed of approximately 1,000-feet per hour and a typical tank farm pipeline inspection is completed in four to six hours.

Figure 3: Inspection path.


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Figure 4: Schematic of an inspection case.


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Figure 5: Manifold.

Figure 6: Launch point (cut out).

Figure 7: Explorer ILI robot has reached the bottom of a tank.

Pipeline pigging and integrity management conference, Houston, February 2020

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Pipetel’s Performance Every Pipetel Explorer ILI robotic inspection returns three primary datasets that depict the integrity condition of the pipe. Firstly, Explorer ILI measures internal and external metal loss and corrosion of the entire circumference of a pipeline through an MFL sensor. A sample is recorded every 0.05 inches of the pipeline traversed; capturing the location, o’clock orientation, percentage wall loss, and dimensions of all metal loss anomalies. Secondly, in addition to metal loss measurements, every Explorer ILI robot detects and measures dents and mechanical damage with a geometry sensor. Finally, Explorer ILI records video footage inside the pipeline with its cameras (Figure 8), providing even more information about the pipeline and complementing the integrity data. The video is viewed instantaneously during the inspection and subsequently by qualified analysts post-inspection. All findings are included in a final report. Once Colonial receives the report from Pipetel, Colonial formulates a repair and remediation plan based on the findings in the final report and validation cut-outs used to evaluate the tool performance. Validation digs are selected based on dimensions and location of the features reported by the tool. Once the pipe is removed from the line, the sample is cut in half, sand blasted, and graded. Figure 9 shows an example of the metallic scale that needs to be removed from the internal surface of the tank line before grading the pipe. Figure 10 shows a segment of pipe that was used to evaluate the tool performance. The NDE results are then compared to the ILI measurements. Once the tool performance is validated, repair/replacement areas are identified.


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Figure 8: An image taken from a camera on an Explorer ILI showing some residual liquid.

Figure 9: Internal corrosion and metallic scale.

Figure 10: Validated internal corrosion.


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Technology Implementation Challenges for Colonial The main challenge with utilizing Pipetel’s technology in Colonial’s system is the level of preparation necessary to ensure the tank line is ready for inspection. As previously stated, the tank lines run from a tank to a manifold, do not have launching or receiving traps, and are generally located in congested areas. The tank lines are sloped with the tank area located at a higher elevation than the manifold area however, due to the numerous line crossings inside the facilities, several low elevation areas and sag bends in the lines may increase the potential for water and debris accumulation. The fact that most of the tank lines do not operate on a continuous basis, and that running cleaning pigs as part of the normal operations of the tank line is impractical, reduces the potential for residue removal from the bottom of the lines. Accordingly, significant efforts to clean the lines prior to inspection are necessary to ensure proper data collection. The line preparation starts with taking the tank out of service and draining all product from the tank line. To find efficiencies in the program, most of the tank line inspections are performed during the API 653 out of service inspection for the tank. Based on the robotic tool dimension, a spool piece up to approximately 20 feet may need to be removed in the tank dike area to load the tool in the line or, depending on the length of the line, in an area that will minimize the number of entry points required for inspection. The tank line has to go through a very thorough cleaning process to ensure a successful inspection. A tank line cleaning contracting company is used for this purpose. Hoses with water blasting nozzles are used to hydro-blast the line and remove any residue present (Figures 11-16). The hoses are typically 300 to 400 feet long and often require cutting additional spool pieces in the line to break the line into segments no longer than 500 feet. The tank line cleaning contractor can typically clean approximately 100 to 300 feet per day on 24-inch pipe. Once the hydro-blasting is complete, the tank line is re-assembled and thoroughly dried. Cleaning pigs are run several times through the tank line to remove water from all low elevation areas. A camera is then run through the line to verify that all water and residue has been removed from all low elevation areas (Figure 17). The preparation and cleaning requirements for inspection are usually the driving factor for the total cost of a tank line robotic inline inspection project.

Figure 11: Sludge in pipe.

Figure 12: Temporary launcher trap for cleaning pig.


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Figure 13: Tank line cleaning.

Figure 14: Water accumulation in pipe.

Figure 15: Return water being vacuumed.


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Figure 16: Temporary receiver trap for cleaning pig.

Figure 17: Cleaned pipe.


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How Pipetel Continues to Improve Technology to Increase Efficiency in Future Inspections In preparation for the robotic inline inspection, Colonial is required to drain and clean the tank line of product to provide a dry environment. Pipetel is aware that this process can be intensive or inconvenient for tank farm operators and is currently working towards feature upgrades that could simplify the process. These upgrades include better sealing of critical components on the Explorer ILI robot so that components have improved tolerance against contact with liquid and robotic mechanisms that could push some liquid out of the way before or during the inspection process. Both of these efforts would reduce the amount of cleaning required before conducting the inspection and thus reducing the cleaning costs incurred for the operator. Summary Colonial has developed a standalone program to assess the integrity of tank lines inside their facilities. Tank line assessments are subject to unique challenges and several assessment methods have been considered for these systems. However, the robotic MFL solution offered by Pipetel has proven to be the most effective to date. Pipetel’s tool provides accurate and reliable data. The performance of the tool has been validated with cut-out pipe evaluations and it has been determined that the tool performs within specification as long as the tank line is properly prepared for inspection. This preparation work comes with many challenges that Colonial has to resolve when using Pipetel’s tool. These challenges can be overcome, but they represent a high impact to the cost of the project. Some of the most significant challenges include:

• The tank line must be thoroughly cleaned and dried before the inspection. Cleaning the tank line requires the use of a significant volume of water, and the process to dry the tank line is time consuming.

• After inspection is completed and spool pieces are installed in the cut-out sections, welding in the tank line is very challenging even after de-magnetizing the pipe.

• A boom truck must be used to lift the heavy tool, which sometimes is challenging and requires extra caution and planning due to limited space inside the facility.

In spite of all the challenges, the high quality data obtained from the tool and the decisions made based on that data make these challenges more acceptable. Continued technology improvements are critical in order to make tank line inspections more cost-effective.

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