Corrosion is the number one enemy of refiners and — to a lesser extent — petrochemical producers. It accounts for over $1.4bn in annual cost and causes half of all pipeline leaks in both upstream and downstream oil and gas.
The Saudi Aramco Journal of Technology estimates that over one third of all maintenance costs in refineries can be linked to corrosion remediation and repairs, while the prevention of just 1% of corrosion issues could potentially save the industry millions of dollars a year. So what can operators do to protect their assets?
“Corrosion prevention, maintenance and control are hugely significant to the lifecycle of downstream oil & gas assets today,” Kjell Wold, business development manager for flow assurance at Emerson Process Management, told RPME.
“From naphthenic acid corrosion to sour water corrosion, hydrogen induced cracking and sulphide stress cracking, corrosion can take many forms in refineries and other downstream assets and can have a highly negative impact on operational integrity, running costs and, of course, the eventual lifetime of the asset.”
Corrosion mitigation strategies play a huge role in prolonging the life of pipelines and plants, while also improving safety, reducing unexpected failures and providing efficient inspection and maintenance plans for equipment, as Stephen Anderson, global director of asset integrity management at Intertek, explains.
“By understanding materials, their degradation and corrosion we can identify effective mitigation strategies such as careful monitoring and control, changing materials or design, suitable inspection and maintenance strategies as well as suitable operating parameters.” Furthermore, operators are advised to put in place a robust and well-thought through corrosion control system, which will help them make better informed long-term decisions based on reliable data, gathered from key matrices.
“These can take the form of key performance indicators such as the form and location of corrosion and the equipment affected through to acceptable operating windows where specific triggers, such as dew point, temperature or pressure thresholds, require specific interventions to ensure long term asset integrity,” said Dr. Derek McNaughtan, general manager of production and integrity assurance at Intertek.
“It is important to have a risk based assessment done to identify the degradation threats to an asset under current operating conditions. With this information the appropriate inspection and monitoring regime can be implemented to verify assumptions made in the assessment and refine monitoring requirements to ensure the correct data is gathered to assess the overall integrity of the asset,” McNaughtan added.
The data can then be used to both assess the current condition of equipment and predict the remaining life, based on inspection derived corrosion rates, allowing operators to plan what remedial actions they need to take in order to ensure the individual equipment and overall asset achieve and often surpass design life in a safe manner, he explained. As producers find themselves operating in ever more challenging conditions, recognition of corrosion as an important challenge to operations and assets as well as overall awareness are improving significantly across the industry.
“The feedback we are seeing from our clients is that with the low oil price there is a continuing focus to make tangible savings by improving operations and optimising systems to be as efficient as possible.
“The main areas that our clients have been requesting support in is verifying that their current corrosion control measures are effective and that the measures they have taken are the most appropriate, especially where their operating conditions have changed either due to process changes or expansion of their facilities,” said McNaughtan.
According to McNaughtan, this can take the form of auditing operators’ standards and procedures to ensure they reflect current industry best practice and updating them where appropriate to verifying what impact changes they intend to make to their operations will have on their current corrosion control regime.
“It also may include testing their incumbent corrosion inhibitors to ensure optimum performance and treatment to identifying the cause of particular corrosion issues they have seen and what additional mitigation measures should be put in place, be that material upgrades, chemical treatments or increased monitoring locations,” he added.
One particularly significant area where corrosion experts can assist operators is in avoiding unplanned shutdowns or unexpected problems due to corrosion.
“By applying the correct risk mitigation measures or optimising the existing ones, the current life of assets can be extended, thereby reducing operational expenditure, minimizing downtime and reducing unplanned shutdowns.
“As an example, a review of the existing corrosion inhibitor treatment by either evaluating the latest chemical technologies or optimising the current treatment regime can result in significant savings in terms of chemical quantities used and stored and increased effectiveness of the treatment,” McNaughtan said.
The oil and gas industry plays a huge role in the global economy and has an even bigger one in the GCC, where governments rely significantly on hydrocarbon developments for their revenue. According to some estimates, corrosion contributes to about 25% of failures experienced during production and if left unabated can spread rapidly, undermine the integrity of assets and lead to significant costs.
“There have been numerous studies reported estimating the cost of corrosion in terms of GDP, varying from country to country, with 3% of GDP commonly quoted from a US government study some years ago,” McNaughtan said.
“This breaks down into costs associated with pipelines and facilities, downhole tubing and capital expenditure for replacement equipment. Any intervention by either identifying corrosion early, or more importantly, controlling the degradation has the potential to offer huge long term savings in terms of preventing leaks and reducing unplanned shutdowns, not to mention the benefits to the environment and the safety of personnel,” he added.
While it is difficult to put a specific numbers on the benefits of corrosion prevention, without a proactive and effective corrosion monitoring system, cost downsides can be huge, says Wold. He argues that timely and regular corrosion inspections, although crucial particularly for ageing assets, are becoming obsolete.
“The days of monthly inspections from off-site personnel are behind us. At Emerson, we like to differentiate between monitoring as a part of an integrity management program and ‘pro-active’ corrosion monitoring or corrosion management. In integrity management, the main objective is to verify the condition of the piping and process equipment to ensure safe operations and to make structured plans for maintenance and repairs – timely and regular inspections that are crucial to asset integrity.
“Pro-active corrosion monitoring, on the other hand, is targeted at detecting changes in corrosion rates before significant metal loss takes place. Such changes in corrosion rates might be down to the fast tracking of corrosion inhibitor efficiency and consumption, or changes due to the processing of high TAN opportunity crudes. For such proactive corrosion management, sensitivity and fast response is essential. The highest resolution and fastest responses are provided through in-line corrosion probes,” Wold said.
“Corrosion mechanisms and forms also change from application to application. As an example, naphthenic acid corrosion is often distributed as localized attacks. It is therefore important that the corrosion monitoring method reflects the type of corrosion monitored. The non-intrusive Field Signature Method (FSM) technology is a good example of a method that will detect localized attacks within the monitored area.
“Hence, we would argue that a complete integrity management program would consist of a combination of regular inspection, permanent integrity monitors and fast response technologies, such as FSM.
“Timely and regular inspections are vital but so are fast response technologies that detect corrosion and potential metal loss in real-time and ensure that remedial action is taken before there is any significant damage,” he added.
Money poses a significant concern for refiners, especially at a time when margins are getting thinner and operators are forced to freeze spending. Invariably, this has stirred a growing interest in more cost-effective, lenient on the purse solutions, which one day might cost companies more than what they have saved.
“Some of the challenges we experience revolve around clients who have budget constraints and need to ensure the maximum benefit from the strategies and technologies they implement. This can result in older, less expensive technologies with lower efficiencies being favoured over the newer, more expensive innovative technologies that have higher efficiencies and require a higher level of expertise for implementation,” Wold said.
With the oil price hovering at just above the $30 mark, many oil & gas producers and refinery operators are looking to cut costs. Therefore it is worth asking to what extent low oil prices will impact investment in corrosion prevention and monitoring.
“The low oil prices have made it even more important to ensure optimal production and refinery processes and the cost effective delivery of hydrocarbons out of refineries. Corrosion monitoring will play a key role in this area,” said Wold.
McNaughtan added: “I believe the industry can’t afford not to take corrosion prevention seriously particularly in this time of low oil prices as it makes good business sense.”
Emerson recently released on the market a highly advanced corrosion monitoring system that can detect and track high TAN (Total Acid Number) crudes and their corrosive elements. This enables operators to blend the maximum amount of such crudes into the product mix and helps mitigate corrosion risk. The benefits of a tool of this kind can be significant for industry operators who tend to use opportunity crudes as feedstocks to reduce cost.
“Crude oil purchasing today represents over 90% of the cost structure of a refinery and is therefore a major area for achieving profitability and reducing costs.
“High TAN crudes is an aggressive but cheap form of crude which has high levels of acidity. Its price can be approximately 80% the price of conventional crude oil. The optimal blending of high TAN crudes and conventional crudes can therefore significant improve refinery profitability as long as the effects of corrosion are closely monitored.
“For example, an increase in opportunity crudes from 1.5% to 3.5% in a refinery with a capacity of 300,000 barrels/day, could result in savings of $7 to $10 million per year based on a $4 price difference.
“This provides a compelling case for proactive corrosion monitoring and the Roxar Corrosion Monitoring System,” McNaughtan added.
The industry is facing a raft of challenges which call for some timely action. Aging plants, stringent industry standards and an increased focus on safety will require accurate corrosion and integrity management information, which isn’t always readily available. Despite the myriad of new technologies on the market, the industry continues to rely on outmoded and cumbersome systems and tools. This is a problem that needs to be addressed if the industry wants to move forward instead of lagging behind.
