One of the more interesting construction defects observed at a plant in Asia is a nearly universal application of coatings that did not cure.
As background, modern "paint" used in a power plant is a complex engineered product often applied in two or three layers. This is because each layer has a purpose. For example, inorganic zinc is often used as a primer, but not suitable as a top coat. Similarly, epoxy is used as a second coat, but not a top coat because it is poor at enduring UV unlike a urethane.
Each of the layers must be properly mixed, and usually is catalyzed with a hardener. The proportion of hardener to base product is very important. Too little, the coating never cures and perpetually stays soft. It's a failed coating. Another important factor is to keep water (rain and condensation) from the coating components. Water affects curing also.
At the plant in question, easily 70% of the coated plant (large coal plant) had coatings that were not cured. To test this defect, ASTM has a MEK (Methyl Ethyl Ketone) wipe test which roughly involves a clean cloth, a little MEK, and... Read more
Collosal. Left unrepaired...
"Old School" Steam Drains
Keep in mind, this is a new plant in operation about one year, in a location where quality plants are built routinely... Yes, this is a NEW plant built to contemporary codes and standards by a large international EPC contractor.
During EPR's review of the Facility, this system is perhaps the single most compelling example of inferior design in the plant. While not the most cost intensive, the effects are broad reaching. The open trench design belches hot condensate on steel, electrical hardware, and other equipment leaving the plant to look ready for decommissioning. O&M personnel are left to perhaps unknowingly assume that facility condition is not important to the owners; how could it be, look at this? In so many ways this is not consistent with the Facility purchased.
The condensate collection system of trenches and transfer sumps has experienced critical deterioration. Serious failures in the concrete infrastructure include trench through-cracks, cementitious erosion, advanced concrete spalling and scaling, sub-grade undermining, differential settlement, and accelerated... Read more
Unknowable, but very significant. Violates Environmental permit, among other problems.
Pillars of Salt & Sand (and Plastic)...
Piers are structural. This necessitates that they are installed correctly with every detail.
As with most construction defects, this is a simple problem of unskilled and unsupervised workers. The problem is compounded by a contractor culture that allows a QC program to run as a "paper" generating endeavor completely disassociated from the facts of field performance. In many cases, it's evident that there is no inspection. This is such a case...
Grout must be installed where to concrete conditions conform to the manufacturers recommendations to assure a strong bond between the materials (concrete and grout). Typically, this involves a rough surface, clear of debris, and free of any existing concrete surface coating, and similar.
Well, in this case, it's hard to imagine how these piers ended up with plastic bags being embedded at the bonding joint, among other concerns.
One certainty, there was no engaged contractor QC or owner involvement.
In the future, the piers will need to be re-grouted as routine maintenance. Unknown cost.
The Lawrence Welk Show
EPR performed a verification of final completion on a large coal plant in a developing country.
A critical system in any power facility is its instrument air (IAS), because a loss of instrument air means a loss of control in many instances. Further, IAS is expensive because air compressors take a material amount of parasitic load in addition to the drying needed to wring out any moisture.
In this facility thousands, or perhaps more, IAS leaks were observed. This is due in part to unqualified installers and also the lack of tools necessary to tighten the joints. Tubing systems are fantastic because they are high pressure, install quickly, and durable if installed correctly. However, contractors often underappreciate that a tubing system is a technical installation that require the workers to be trained. In this plant it was apparent that any joint which did not leak, was purely an accident, because the recommended OEM installation practices were simply not followed.
This will cost the Owner hundreds of thousands per year in additional compressor usage (power and increases... Read more
No Savings. Probably cost more with unqualified personnel.
Really not possible to repair all leaks. Owner Cost will be severeral $100k/year for plant life.
Rupture Disk Vent Safety
During a plant final completion punchlist walkdown, the EPR team observed a serious condition with steam rupture disk vent stack locations. The discharge point was face-high at an operator's platform.
These disks relieve pressure from a very large "reservoir" LP header at about 800F and perhaps 250psig. At some prior point, during early operations or commissioning these disks relived. The energy from this release had ripped insulation and metal jacketing from the above cold-reheat piping which was later partially repaired. However, the insulation is still imbedded in structural steel and other equipment in the area from the force of the release.
It is a serious safety concern when a standard design platform for personnel access is above the vent stack. If any personnel would have been located on the platform during this release, they would have no doubt been seriously injured or a possible fatality would have occurred.
Minimal. However, potential Owner risk is significant if a fatality occurs.