STACK INSPECTION AT GAS-FIRED COMBINED CYCLE PLANT

Like any other power plant, a gas-fired combined cycle power plant requires regular inspection strategies to ensure a long-lasting asset performance. Industrial Access offers years of experience in conducting thorough inspections of HRSG and bypass stacks, breeching ducts, and surrounding equipment in combined cycle power plants, and providing optimal maintenance and repair solutions.

Components of a combined cycle plant are subject to extremely high heat, wide temperature fluctuations, humidity as well as harsh environmental conditions. Unattended steel structures, like stacks, risk failure due to corrosion and thinning of shell, which may lead to pinholes and buckling; overheating causes deterioration and loss of thermal insulation and protective coatings; stress, movement, thermal expansion – all contribute to gradual degradation of a stack and surrounding equipment.

Facilities also commonly face various circumstances that further increase the risk of damage, such as frequent changes in duty load that cause thermal fluctuations and fatigue cracks, or improper shutdown layup procedures that gather moisture and accelerate corrosion. While some situations can be preventable, it is never fully certain or unlikely that no concerning damage occurred.

Because of that, it is important to carry out regular inspections and routine maintenance plans to ensure everything is in proper working order. Any signs of damage, such as corrosion and defects, rust, thermal fatigue, overstress, thinning and more, require professional attention to be addressed and mended for the safety, efficiency and longevity of the plant.

Technicians at Industrial Access (IA) are experts in providing rigging and unique access solutions for industrial work at height. The access approach during an inspection is developed with close attention to each individual structure and situation at hand. The crew is trained in rope access rigging and techniques to deliver services at maximized efficiency and safety, unparalleled by any other contractor. IA’s technicians are certified by the Society of Professional Rope Access (SPRAT), which “provides instant recognition and credibility for the Technicians who carry it, and the companies who invest in it.”

IA’s expert technicians, with the assistance of our engineers, can perform strategic inspections for elements of combined cycle power plants to determine that they are operating as designed. Inspections are scheduled and conducted in accordance with ASCE guidelines that detail the recommended extent and frequency of inspections of power plant stacks and appurtenances. It is always advisable to proactively schedule regular inspections and preventive maintenance work to identify and correct any minor issues before they develop into conditions requiring extensive shutdowns and costly repairs.

Recently, IA performed an ASCE Class II condition assessment for two 160’ HRSG steel stacks in a power plant in the southeastern US. To enable the inspection, IA’s specialists first performed a washdown and tool cleaning of the exterior and interior of the stacks and their breeching ducts to remove any debris and buildup present. Then, utilizing rope access techniques, the crew examined the condition of the shell, flues, coatings, linings, and other appurtenances that could point to defects, deterioration or structural vulnerabilities. Photos and Ultrasonic Thickness (UT) readings are taken for an extensive evaluation of the stacks’ condition and structural integrity. Other Non-Destructive Tests (NDT) can also be implemented to easily identify any areas of concern.

Once an inspection is completed, IA develops an assessment report, detailing and demonstrating the results of the inspection, and provide a maintenance strategy guide with recommended future repairs and preventive measures based on their urgency. Since it isn’t possible to surely predict when a structure failure can occur, the best insurance against major emergencies is to plan for regular routine inspections that spot any concerns early on.

Even though different components of a natural gas combined cycle power plant and its HRSG system work together to extend the lifecycle and efficiency of the plant, they must consistently be in good condition to function at full capacity. Therefore, it is recommended to implement a routine inspection schedule that prioritizes regular preventive maintenance in order to reduce the necessary frequency for more extensive, intrusive, and costly inspections as well as repairs. Regardless of the situation, IA can provide thorough condition evaluations that will identify any immediate issues as well as long-term areas of concern. A risk mitigation plan, developed by industry experts at IA, will enable your facility to always remain one step ahead.