Corrosion in chemical plants doesn’t wait for a convenient shutdown. We recently tackled a severely corroded steel column on a pipe rack, where aggressive environmental conditions had compromised the original cross-section. Sandblasting showed that more than 70% of the cross-section was gone.
In a chemically aggressive environment, corrosion occurs in places where rainwater tends to collect in depressions, and these areas require strengthening.
Assessing a corroded steel column
A visual inspection alone cannot establish the full condition of a load-bearing member. Once loose corrosion products have been removed, the remaining steel can be assessed more clearly and the areas requiring further analysis can be identified. In this project, sandblasting revealed a loss of more than 70% of the column cross-section. This finding calls for a proper engineering assessment before decisions are made about continued use, repair or strengthening.
Particular attention should be paid to column bases, connections and locations where water can collect. In industrial environments, exposure conditions may accelerate steel deterioration, so an assessment should consider details and drainage as well as visible surfaces.
Strengthening a pipe-rack column while the plant remains operational
The key project constraint was to keep the installation running. The task was to develop a strengthening solution for a corroded pipe-rack column that accounted for the existing loads, the structure’s geometry and the conditions for carrying out the work. The concept shown in the sketch uses additional plates to strengthen the HEA column.
The scope and connection details must be based on the specific structure. The design needs to consider the condition of the member, how forces are transferred, how new and existing components work together, and the effect on adjacent elements. Each node and connection detail must be considered against the actual geometry and site constraints. There is no single strengthening detail suitable for every corroded column.
What can the engineering scope include?
Depending on the available documentation and the condition of the structure, the work may include:
- review of drawings, load data and information about the structure;
- assessment of the existing condition and identification of missing information;
- structural calculations and verification of the selected strengthening option;
- design drawings and details needed for coordination and construction;
- coordination with the installation and other disciplines within the agreed scope.
The scope is always agreed for the specific facility. Where numerical analysis is required, learn more about our structural analysis and FEA calculations. Our technical consultancy can also help assess the issue and identify the next steps.
When should you consult an engineer about structural strengthening?
Significant corrosion loss, flaking coatings, deformation or persistent moisture around column bases should be assessed early. An initial consultation can establish what information and measurements are needed to develop a responsible solution. A visible loss of steel should not be assumed repairable by simply adding plates without checking the load-bearing system.
MESTIL provides structural design, engineering calculations and technical support for industrial facilities. You can send the site location, photographs of the damage, available drawings and a short description of operational constraints. Contact MESTIL about the assessment and design of a structural strengthening solution to discuss the appropriate scope of work.
Frequently asked questions
Can a corroded column be strengthened without shutting down the plant?
That depends on the condition of the structure, its loads, access to the member and the construction method. In this case, the design brief assumed that the installation would remain operational. This must be assessed and confirmed for each individual facility.
What information should I prepare for an initial consultation?
Photographs, the member’s location, available drawings, load and operating information, and any planned access or shutdown constraints are helpful. Any missing data can be identified during the technical assessment.
Why assess the steel after it has been cleaned?
Coatings and corrosion products can hide the actual steel loss. Cleaning makes the surface easier to assess, but selecting a strengthening solution still requires structural analysis and a review of the member’s operating conditions.