Written by Scott Schreeg | Power Plants
The SVI BREMCO inspection team inspected the intake and exhaust stack at a power plant. After the thorough inspection, the team recommended necessary maintenance and repairs.
What Type of Inspection Was Performed?
The team performed a visual and ultrasonic inspection of the intake and exhaust stack for the plant’s Unit #3. The goal was to assess the components’ overall condition to determine whether they needed repair, replacement, or only future monitoring.
What Did the Intake and Exhaust Stack Inspection Find?
On the exhaust stack, at the entrance region, three ceiling panels were loose because most connection assemblies (plate washers, threaded rods, nuts) were not secured. A 3′ x 1′ plate was missing from the east side near mid-height. Regarding the floor plates, we identified various cracks on previously installed patch plates, as well as several bulged regions. We found a crack in the west wall above the access hatch.
The diagonal member of the added pipe supports was completely cracked from the turning vane assembly, and the upper connection bolt at the linkage connection had shifted inward and was slightly skewed. No concerns were noted about any baffle when viewed from above or below. Most spacer panels did not span the full baffle height, and these regions showed heavy rust and scaling.
On the upper extensions, several regions were split open along vertical seams of inner panels, and cracks were identified in the channels at past welds in the upper corners and at welds at channel splice locations.
The concrete foundation pads had significant cracking and spalling on the southeast quadrant, with thin cracks in the other areas. No immediate concerns were observed with the steel supports or slide plates. There was no corrosion or deterioration in the anchor bolts and nuts. The siding and attachment members were in good overall condition.
The intake stacks also had inspection findings, including heavy deterioration with heavy levels of rust and scaled plate. Surface deterioration was visible, but there were no signs of cracked or bulged regions. All baffles appeared secure and in the proper position. The surfaces along the upper perimeter deteriorated due to moisture infiltration from the upper enclosure. Minor fit-up, connection weld, and painting issues were found in most regions. There was pitting in a plate local to the drain opening, and two holes were found in a plate in the northwest corner.
Read about SVI BREMCO’s capabilities in a similar project: Simple Cycle Combustion Turbine (CT) Exhaust Duct and Stack Thermography Analysis in Virginia.
What Intake and Exhaust Stack Solutions Were Offered?
After completing the stack inspection, SVI BREMCO recommended that although no single region or component of the exhaust stack was excessively deteriorated, the sheer number of defects across all parts warrants complete replacement of the stack. To help decide between repair and replacement, SVI suggested that the plant request cost estimates for the following repairs so a comparison can be made.
- Secure all ceiling plates and stiffeners in the entrance region.
- Replace missing side plate in entrance region.
- Repair the cracked side wall plate above the access hatch.
- Remove and replace all floor plating.
- Repair or replace the broken pipe of the turning vane support.
- Replace the displaced support bolt (upper east side of vanes).
- Exposed regions of plates above the spacers (between each
- baffle) to be cleaned and coated.
- Bridge all seams between the perforated plates in the upper enclosure with a stainless plate.
- Repair all cracks in the enclosure corners and splices.
- Perform concrete NDE for all four foundation pads to determine their structural integrity.
The intake stack also had recommended repairs. On the baffle enclosure, the exposed regions of the carbon steel plate between the 15 baffles in the upper elevations require repair or replacement. If the baffles can be removed, this region should either be cleaned (sandblasted) and coated (painted) or have the carbon steel areas replaced. If the baffles cannot be removed, clean (wire brush or sandblast as much of each region as possible) and coat, or install a cover plate to encase the deteriorated regions. The cover plate could be secured to the enclosure at the upper and lower elevations.
On the left-side intake, patch the floor plate holes. Clean, repair as needed, and coat deteriorated welds and areas along angles and patch plates around the perimeter.
Does Your Plant’s Intake and Exhaust Stack Need This Type of Inspection?
SVI BREMCO professionals design and install advanced solutions for industrial power plants’ intake and exhaust stack systems. If your plant needs a comprehensive inspection, contact us to schedule a site visit.