NOTE: The sponsor of this content may contact you with more information on this topic. Click here to opt-out from sharing your email address with this sponsor. (This link will not unsubscribe you from any other BIC email list).
Major oil and gas refineries are beginning to see demand increase for the first time since the global pandemic.
According to a recent Bloomberg article, more than 1 million barrels of capacity has been lost during the past two years in the U.S. market. With a tightly supplied market and demand set to challenge 2019 levels, plant owners have been exploring ways to prevent unplanned shutdowns and improve asset life.
One of the primary causes of process disruption is the issue of corrosion and metal wastage. There are several viable options available to address the corrosion mechanisms with a Corrosion Resistant Alloy (CRA) barrier. The technique used to apply this CRA will predominantly be determined by the shutdown time available to carry out the application.
While welding continues to be an option, over a decade of successful High Velocity Thermal Spray (HVTS) applications, supported by inspections and laboratory validation, have confirmed this solution to perform “in the same league” with several added benefits.
Refineries, particularly those with time constraints, are seeing critical paths being reduced by up to 50%; with the average shutdown day costing refineries approximately $1 million USD. The significantly faster application time of HVTS coupled with the absence of heat treating requirements is delivering major savings.
Maintaining Uptimes
Welding repair
Mission critical equipment, including process vessels, towers and drums play a major part in maintaining the uptimes and levels of production of oil and gas plants worldwide. Media being processed inside these vessels can be highly corrosive in nature. Furthermore, fuel diversification and changes in the process can create new corrosion mechanisms.
The presence of HCL, H2S, amines, and other corrosive media in high temperature environments corrodes carbon steel base material. Pitting corrosion, acid attack, stress cracking, heat affected zone corrosion and erosion will require a prompt intervention.
Fitness for Service
Once it is evident that the vessel is losing wall thickness due to corrosion, the countdown begins. If the vessel wall thickness has exceeded its minimum corrosion allowance, options available for the operators become significantly narrowed down to major mechanical repairs or replacement of the equipment.
Welding repair application
If intervention takes place before this time, or, if Fitness for Service (FFS) evaluations deliver a favourable result, where the vessel still maintains its operational integrity, there are several options on the market that can be considered.
How can Corrosion be Prevented or Stopped?
There is a variety of solutions available on the market to help prevent the process of corrosion, including welding, various coatings, and Integrated Global Services (IGS) High Velocity Thermal Spray (HVTS).
Welding is a commonly used solution in the oil and gas industry, both for rebuilding degraded areas of wall thickness and providing a corrosion-resistant alloy barrier.
Welding carries some fundamental drawbacks. A common issue is distortion of the shell due to heat input during the welding process, which can further require crane support to the equipment. A high degree of stress gets added during welding, especially on thinner wall vessels. Additionally, the weld procedure, code, or environmental conditions may require heat treatment prior to or after the application as an additional step to the repair solution.
There is also a question of time and costs. Welding is a relatively slow process with an application time of 10 – 16 ft2 (1 – 1.5m2) per weld head per shift and can cause additional delays in bringing the asset back into service. During a critical path period, using welding for corrosion protection can have a significant financial impact.
Thermal spray application
What about Thermal Spray?
Thermal spray technology has been utilized for the application of CRA since the 1980s, spraying metals widely used in the welding process. However, it was quickly noted that the thermal spray process itself can negatively affect the condition of the material being sprayed. The resulting cladding, when using traditional metal alloys and commercially available thermal spray equipment, is permeable. This permeability coupled with internal stress and a lower bond strength with the base metal creates a path for corrosion and premature failure. These early failures have resulted in an understandable and rather universal distrust of early iterations of commercially available thermal spray technology. The issues with thermal spray cladding raised some important questions, including whether it was possible to eliminate the permeability, porosity, and internal stress of the thermal spray applied coating and improve bond strength.
What is the Best Solution for Preventing Corrosion?
With corrosion causing disruption to many refineries, the industry needed a solution that could eliminate the permeability, porosity, and internal stress of commercial thermal spray without compromising bond strength delivering a robust solution similar to welding.
IGS understood this industry problem and developed its own proprietary solution — a corrosion-resistant High Velocity Thermal Spray (HVTS) technology. Designed to protect the base metal in high corrosion environments, HVTS involves the simple application of a non-porous high nobility metal alloy.
Not only is the application process considerably faster than welding, there are no stresses imposed on the base material during the application process. Furthermore, the HVTS process does not generate any dilution. The quality of the cladding remains uncompromised and there is no potential for galvanic corrosion due to dissimilar metals.
Comparison Table
HVTS provides excellent up-front cost reduction and long-term ROI due to material and labour savings. Savings as high as 50% are frequently achieved. Furthermore, since HVTS doesn’t impart stresses to the base material, there is no requirement for heat treatment
either before or after application, resulting in substantial time savings and additional costs.
Case Study #1: HVTS Saves Days of Critical Path Time on Alky Reactors
Corrosion in SAAU Unit Reactors
A large oil refinery in Texas required a solution to corrosion that had taken place within its alkylation unit reactors, caused by a high concentration of sulfuric acid. The plant required critical path maintenance work to be carried out and had two options available to fix the issue: either potential window replacement (partial can section replacement) with fabrication and welding or Integrated Global Services (IGS) High Velocity Thermal Spray (HVTS) solution.
Sulfuric acid alkylation unit (SAAU) reactor drawing showing some internal mechanicals
IGS HVTS Solution
IGS’s HVTS technology underwent extensive testing and analysis conducted by the plant’s corporate department. The solution received technical approval and IGS was subsequently chosen to complete the application on multiple alky reactors.
The HVTS process includes true high-velocity application. This cutting-edge technology allows IGS to apply claddings with much greater density and decreased permeability, while
keeping internal cladding stresses low.
Challenging Application
IGS technicians were able to complete the application within six shifts across three days per reactor. During the process there were several challenges such as the geometry of the vessel including internal mechanicals inside the units. The experience and skill of the IGS operators enabled these challenges to be overcome safely whilst adhering to the work scope and project timeline.
The Benefits
The key benefit for the refinery of choosing HVTS as opposed to welding is the considerably faster application process. The IGS team was able to complete the application at least three times faster than what a welding application would have taken. The average cost to refineries of $1 million USD per critical path day meant that the use of HVTS delivered significant savings.
IGS HVTS applied onto a section of a sulfuric acid alkylation unit (SAAU) reactor.
IGS Comment
“We are really pleased with the outcomes we have achieved for our client in Texas,” said Eric Duvekot, director of IGS North American Operations. “It was a challenging project due to the internal configuration of the vessels, but our team has the expertise to adapt and find safe solutions to problems when they arise.”
Duvekot said the client was satisfied with the results, the work was completed safely and within the allocated timeframe, and the units were protected from further degradation.
“We continue to expand the possibilities of HVTS alloy cladding and its impact on shortening critical paths while delivering robust asset reliability,” said Duvekot. “HVTS alloy cladding successfully withstands HT, HP, acidic, caustic and other harsh operating environments, positioning itself as the preferred corrosion resistant alloy.”
Case Study #2: Proven Alternative to Welding in a Corroded Fractionator Tower
An Ageing Giant
Fractionator tower
Built in the late 1970s, the 126,000-bpd refinery is one of Saudi Arabia’s oldest grassroots refineries. It comes as no surprise that some of its existing equipment is now approaching the end of its life.
Corrosion Emergency
During a 2014 shutdown, the fractionator tower was found to be suffering pitting corrosion and required urgent protection to prevent the loss of integrity and a need for replacement.
The operator considered two alternatives:
1) Welding
2) IGS HVTS (High Velocity Thermal Spray)
Welding would have come with a requirement for tower stabilization and post weld heat treatment making it a less practical choice in terms of cost and time, with this being an emergency.
IGS HVTS Application in 2014
HVTS application was completed in 84 hours. An additional 72 hours were utilized to set up, pull in and out of the vessel as well as complete other tasks such as blow down, inspection and sealing. A total of 10 days were spent on site, working within the critical path of the shutdown.
Extended Scope in 2017
HVTS cladding applied in 2014 was inspected and found to be in good condition. Additional scope was identified during the initial outage inspections. Working together with the shutdown team IGS mobilized equipment and personnel, completing the expanded scope within the required shutdown timeframe.
IGS HVTS inspection in 2020
2020 Inspection
The entire 132m² area cladded with HVTS was inspected in 2020. The IGS HVTS Cladding was found to be in good condition with minimal to no thickness loss and ready for service.
Summary
Corrosion continues to be a costly issue for refiners around the world. With demand on the rise again, plant owners are taking measures to secure profits, reduce unplanned shutdowns and protect process assets from degradation and drops in performance.
IGS understands the costly implications of corrosion and has more than 35 years’ experience of helping clients solve metal wastage and reliability problems in mission-critical equipment.
Need Asset Corrosion Protection Advice? Contact IGS today and receive expert advice within eight hours.
