How refineries are saving time and money protecting assets
The oil and gas industry is seeing a rise in demand and is taking vital steps to avoid disruption in production by preventing corrosion in process vessels, towers and drums
Integrated Global Services
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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 one 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.
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.
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.
What about thermal spray?
Thermal spray technology has been utilised 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.
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.
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