Work performed
- Entry into the GCT with rope access technicians
- Thickness survey of the GCT walls at 1 m intervals, top to bottom
- Short-term remedial solutions to reduce unplanned downtime
- Long-term solutions for the next scheduled maintenance
Scope
A cement factory in Zimbabwe reported inefficient temperature control in its gas conditioning tower. The outer casing was visibly sound, so the inner casing had to be inspected.
Access
TALOS rope access technicians entered the tower from the top, giving safe and efficient access to the entire 6 m diameter, 17 m high tower. An ultrasonic thickness and coating gauge (Dakota Ultrasonics CMX) was used to assess the structural integrity of the inner casing.
Solution
Readings were taken at 1 m intervals over the full 17 m of the cylindrical section, divided into six vertical sections for a comprehensive analysis. As a control, the gauge was first verified on a steel block of known thickness; inside the tower, three readings were taken within each 10 × 10 cm area and averaged.
Sections of the casing had corroded and thinned, and holes were starting to form at the bottom of the tower — the reason for its inefficiency. The thinning was caused primarily by corrosion and scaling, accelerated by high temperatures and dissolved oxygen.
Results
TALOS found it feasible to carry out remedial works to reduce downtime ahead of the scheduled maintenance. Given the corrosion of the inner casing and the peeling of the outer casing, the cylindrical section needed further reinforcement to avoid the risk of collapse. TALOS also recommended periodic condition assessments after the remedial works.