Industrial Access conducted a condition assessment of ten coal silos. A comprehensive visual inspection as well as Ultrasonic Thickness readings were performed during multiple drops utilizing expert rope access techniques. Based on the inspection findings, Industrial Access developed a plan of strategic recommendations for repairs, enabling the facility to always remain one step ahead.
20 days for inspecting 10 bins
Completed during a pre-scheduled outage
Completed with no safety compromises
A power plant in the southern United States was scheduled for a thorough inspection of their ten coal bins. Each A-36 carbon steel bin is 64’ high with 24’ diameter with stainless steel cladding. Coal is a highly corrosive material, especially with moisture present due to environmental conditions. The resulting atmosphere inside a coal silo is corrosive to the steel plating, particularly if there are areas at which the level of coal stored is maintained. Coal silos should be regularly assessed to ensure that the steel plate, welds, cladding, and beams are in good condition and not putting the facilities at risk for structural failure.
Cone cylinder coal bin
Rope access rigging system
Accessing coal bins using ropes
Access approach during coal silo inspections is situational and determined by each silo’s structure and environment. Fortunately, Industrial Access (IA) has trained and certified technicians who are experts at rope access techniques. Rope access is the most efficient and cost-effective solution when it comes to inspections of confined spaces. In these coal silos, the rails for the tripper car as well as interior roof beams were used as support to rig rope access equipment, allowing the team to easily survey every inch of the bin’s interior.
Interior rope access during inspection
Interior bin inspection in progress
Steel cladding anomalies
IA inspected each coal bin individually and provided the plant with an elaborate report detailing noted anomalies and testing results of each bin. The most imminent concerns were identified to be in the poor condition of silo roof beams. In most bins, roof beams were found heavily corroded with complete metal loss in some areas of the web. Additionally, the crew noted evidence of oxidation on bin walls and roof, some heavy pitting, erosion, gouge marks, and pinholes in the steel plate, cladding, and welds. Any defects, such as buckling of the plate and missing bolts, were also identified in the inspection report. IA’s thorough UT readings showed significant thinning in some areas of the bins.
Severe roof beam corrosion
Pinholes and corrosion
To conclude the inspection, IA provided the client with a list of repair and maintenance recommendations classified based on their urgency. For example, the most immediate concern was determined to be the condition of the roof beams. All the corroded beams were recommended to be reinforced and/or replaced at the earliest to prevent collapse of the roofs. Any missing or loose bolts should be replaced or tightened. Any areas of corrosion, thinning, and buckling in the steel should be repaired and holes must be patched to maximize the structure’s longevity. Alternatively, an engineered reinforcement solution may be designed and implemented as required to ensure structural stability.
Overall, the inspection was completed successfully, enabling the plant to recognize the condition of their coal bins and determine their further steps towards mitigating any associated risks. When it comes to inspections, it is highly recommended not to wait for signs of present anomalies before scheduling a condition assessment. Inspections should be carried out before a silo is in bad shape with potentially irreparable damage. Routine inspections and maintenance are crucial in ensuring the safety of a facility and preventing extensive future repairs.