Mark Susich, Above Region Pressure Systems Integrity Discipline Leader at BP, has over 30 years’ experience in the development, implementation, and management of pipeline and pressure systems integrity management programs. Before joining BP, Mark managed subsea, topside pressure system piping, and onshore pipeline integrity, maintenance, and programs in Cook Inlet for Marathon Oil Corporation® in Alaska.
Upon joining BP in 2004 as Pressure Systems Inspection Team Leader, Mark had ownership of piping inspection strategies, procedures, plans, and responsibility for integrating new NDT technologies. During this time, Mark realized the fundamental need to change the way corrosion under insulation (CUI) is managed from non-standardized, ad hoc inspections to a standardized, data-driven, risk-based inspection program.
In 2014, Mark assumed the role of Above Region Pressure Systems Integrity Discipline Leader at BP. Among many other responsibilities, he has worked to drive standardized Risk Based Inspection programs across BP’s Upstream Production Division worldwide.
One of Mark’s best learnings in Alaska was CUI because they have been fighting this space for over three decades. Going back to 1984, one of the first failures was in a high-pressure artificial gas lift line. Mark states, “It is amazing how history keeps repeating itself, but how little we truly understood the damage mechanism.”
The insulated piping on the North Slope was fit for purpose for an Arctic desert environment by design. However, in the late 1900s and early 2000s, maintenance decisions and deferment opened the door for CUI to manifest itself as the North Slope’s predominant integrity threat. In Alaska’s case, the carbon steel piping was not externally coated. They relied on metal sheathing and insulation as the primary external corrosion barrier. Deferred sheathing and insulation maintenance meant that after 30 years of operation, 50% of the insulated piping inspected had now become wet. CUI was not widespread. However, they had a corrosion cell and everything to initiate corrosion. According to Mark Susich, “If you are not removing and mitigation wet insulation, you have to manage it as a susceptible area, and this requires a robust CUI inspection program, as the inventory is dynamic and grows over time.”
By 2014, before Mark left Alaska, BP performed over a hundred twenty thousand CUI inspections in a year, well over a million linear feet a year, and mitigating about five thousand locations.
Working with piping in Alaska has shown Mark that insulation can go from wet to dry and that water can migrate. “Water may enter in one place, but it may accumulate in another, and you need to understand that transmission of moisture in your piping system.” If you are deferring maintenance, then your CUI inventory is growing and increasing the demand on your NDT resources. This growing CUI inventory puts a considerable burden on your inspection program and your management strategy.
The Problem with Managing CUI
There is no unified path and standard practice to manage CUI. Everyone is managing it differently, and few companies have a good handle on how to manage it.
One common method for managing CUI is to strip the insulation at defined intervals, including good insulation, to look for potential problems. The problem with this strategy is you’re prematurely removing good insulation. Most operators do not have useful metrics such as find rate, the real damage of pipeline coating, actual damage of the substrate, and how much non-fit for purpose piping you have to determine the effectiveness of the stripping strategy. Before they standardized their processes, BP spent 10- 30 million dollars a year stripping good insulation, looking for a potential problem, without any data to support the activity.
Another method for managing CUI is to rely heavily on various forms of NDT. When NDT service providers assess piping, they evaluate the piping condition, whether there is damage or degradation to the substrate, to determine if the location is fit-for-service.
Inspection as an NDT activity is a lagging indicator because the damage has already occurred. There is no single NDT technique or method that you can use in every situation and configuration that will accomplish the objective of understanding the damage state.
“You need a suite of tools, and the OpenVision system is part of this suite of tools,” says Mark.
Time-Based vs. Risk-Based CUI Inspection
Along with different methods for managing CUI, there are also various approaches for using NDT to manage CUI. The two most common practices are time-based inspections (TBI) and risk-based inspections (RBI). In a TBI program, you repeat an inspection activity at a set interval, based on the class, such as every 3 or 5 years. In an RBI program, you have technical drivers that initiate inspection activity.
BP doesn’t believe time-based inspection meets the objective of understanding the damage mechanism and prefers to utilize RBI as a data-driven approach to manage CUI. Their RBI program has allowed BP to make some fundamental leaps forward in understanding the environment’s damage mechanism and why certain CUI environments behaved as they did.
“Let’s take Asia Pac’s Tangguh, an onshore LNG facility on the west coast of West Papua. It’s a tropical jungle where it rains so much there’s no chloride buildup on the piping; it just washes right off. However, you have insulated piping, so after that monsoon season, that would be ideal for going out and assessing the barrier and the sheathing to look for wet insulation and corrosion byproduct. It is a desert in Oman, but you could have high-temperature differentials where you can have condensation.”
As your CUI inventory grows, you need to be agile. It’s essential to have a suite of tools available that you can take off the shelf, with competent operators, and go out there to screen and assess your higher risk piping quickly.
“With something fast like OpenVision, you can cover a lot of linear footage in a shift, in a day, in a week, in a month. This allows you to do scans more frequently and as needed.”
Corrosion is not linear; plants and the environment are always changing. This creates a challenge to managing CUI and is where NDT and the application of a good RBI program using data and engineering rigor work best. The questions of why, where, and what drove BP to create the most extensive CUI inspection program in North America, if not the world.
A Standardized CUI Practice Emerges
To educate, create alignment, and drive standardization, BP established a 4-step process for managing CUI, including pre-detection, detection, screening, and sizing.
For pre-detection, you need to understand your inventory and CUI susceptibility. Your CUI inventory is dynamic; as plants age, the insulated system will break down with time. This is where the fundamental understanding of the environment’s damage mechanisms and why specific CUI environments behave as they do comes into play. “For example, in Alaska, every time a snowblower throws that baseball-sized piece of gravel at a piece of sheathing and punctures it, you have now created a new CUI susceptible location,” explains Mark.
Next, you want to fast-screen your inventory to look for moisture to determine if it is wet. If it is, we move on to the detection step.
During detection, you need fast screening capability using real-time radiography to look for a corrosion byproduct profile. Once BP knows they have water, they use OpenVision to see where they have corrosion byproducts. This allows BP to take tangential shots in real-time to see things like “how long is it” and “how wide” and chase the damage out.
“The beauty of [OpenVision’s] C-arm, from an architecture point of view, is it is easily maneuverable. “
There are some relative rules of thumb to assess how bad the damage to the piping is. You want to understand the fitness for service of the remaining ligament so you can strip it, remove the corrosion byproduct, and now size it. At BP, they will remove the blister and the corrosion scale, take ultrasonics to understand the remaining ligament, then perform a fitness for service calculation.
Throughout each of these steps, a suite of tools is utilized. To drive standardization in their testing methods and consistency with data, BP outlined four categories for NDT piping inspection tools:
- Primary (i.e., preferred)
- Secondary (i.e., recommended)
- Not recommended
- Not allowed
BP then reviewed the numerous NDT tools used for each step in their 4-step CUI management process and assigned them to one of the four categories. This categorization helps to control their vendors and, more importantly, drive the right behaviors within BP. For detection, OpenVision is BP’s primary mechanism. When we asked Mark how OpenVision helps with their CUI program, he answered:
“The benefit that the OpenVision system provides to the industry is the ease of operation and fast screening capability. It checks a lot of boxes as far as assessing that pipework for the presence of corrosion byproduct. It’s lightweight, it’s wireless, it’s fast-screening, and it’s real-time.”
There has been no unified path or standard practice for managing CUI, with very little data driving decisions around inspection. We are excited to see BP lead a data-driven approach to manage CUI and are honored to see OpenVision rated as one of their primary tools for detecting corrosion indicators.