Civil infrastructure is a key component in any process facility, providing critical support to equipment, piping, instrumentation, electrical components and more.
Wiss, Janney, Elstner Associates (WJE) is a globally recognized firm whose engineers and materials scientists contribute their expertise daily to evaluate and design repairs and retrofits for critical infrastructure of all types and sizes in process facilities.
This case study showcases WJE’s expertise in assessing and designing repairs for a catalytic reformer support structure after personnel with a Gulf Coast plant contracted the company to perform a condition assessment to determine the criticality of repairs needed.
Concrete tabletop repairs for reformer support
Case study: Catalytic reformer support in civil infrastructure
WJE performing assessment of catalytic reformer support structure.
The structure was a conventionally reinforced cast-in-place concrete tabletop that supports a catalytic reformer. The concrete tabletop consists of a 4.25-foot-thick upper deck. The upper deck has an octagonal penetration that allows the bottom head of the catalytic reformer and associated piping to pass through the deck. Four square concrete columns extend from the mat foundation to the upper deck. Concerns arose after several large concrete spalls fell onto the level below.
Condition assessment
A condition assessment was conducted during a planned short-term outage at the plant. This timing allowed work to proceed safely, avoiding the intense radiant heat of the catalytic reformer. The assessment consisted of a visual and tactile survey and concrete material testing. The visual and tactile survey identified widespread spalling with exposed and corroded reinforcing and delamination of the sides of the octagonal penetration in the upper deck and along the bottom of the upper deck.
Powder samples were collected through discrete concrete drilling to test for acidsoluble chloride content. The chloride concentrations from the samples retrieved from the upper deck greatly exceeded the values expected to initiate corrosion. Through the findings of the condition assessment, it was concluded that heatrelated deterioration of the concrete and chloride-induced corrosion significantly accelerated by the heat were the primary causes of the distress. Repairs were recommended during the next major turnaround as unmitigated corrosion and heat deterioration would continue to occur.
Repair design
Following the condition assessment, repairs were designed. The goals of the repairs were to restore the structural capacity and to extend the service life of the structure. WJE developed repair drawings detailing the repairs. The scope consisted of partial depth concrete repairs with distributed galvanic anodes on the sides of the octagonal penetration and the bottom of the upper deck. This required the removal of deteriorated and unsound concrete, and surface preparation of the concrete substrate and steel reinforcement. Welded wire reinforcing was detailed as skin reinforcing on the outside of the galvanic anodes to control crack widths on the exposed faces. Cathodic protection was detailed with eight unique zones so refinery personnel could monitor the performance of the system.
Despite significant concrete deterioration and an aggressive schedule, repairs were completed on time and within budget during the next turnaround. The implemented repairs extended the service life of a critical piece of civil infrastructure and allowed for the continued operation of the catalytic reformer.
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