Debris at Heights
At a new plant in the Middle East, EPR encountered an alarming amount of debris on steel members, gallery platforms, and other horizontal surfaces up to 150' in elevation from grade.
Power plants move, vibrate, and have operating transients where loads are imparted on the structures and equipment. Essentially, these items will eventually become falling debris with the obvious safety implications.
To further the concern some of the items are quite significant. Pieces of angle iron, bolts, nuts, wedges, grinding wheels, and a limitless amount of other items.
In this particular plant, EPR made the contractor clean up one unit. The debris collected filled a 10-yard dumpster. There were an additional 15 units in this very large plant.
Most contractors have a clean and close process, but in this instance and in others evaluated by EPR, no real effort was made by the contractors to present a finished product.
Minimal, unless a serious safety incident occurs.
A plant was evaluated that had an extensive desalination operation where seawater was flashed to create drinking water.
On the roof of the process equipment, there were insulated and uninsulated bays. One of several coatings problems was the difficulty with this arrangement related to coating selection. The top of the evaporator is essentially flat with bellies in the areas between the structural stiffeners. Water tends to collect in these locations and will not drain. In some cases, drain holes didn’t exist so water has been pooling for a couple years.
In these areas of the tops, the coating selection (urethane) was not suitable for water immersion and breaks down progressively. On the other hand, leaving the surface in epoxy would solve the water damage problem, but is not a solution because it is susceptible to UV breakdown. Therefore, the coating system as installed was not compatible with the propensity of the surface to hold and pool water.
This was not an academic concern, as there are indications the coatings had already failed. One photo shows the adhesion x-cut... Read more
Unknown, but significant.
In a Middle East plant inspected, recurring problems with the process drain system was discovered. It originated from a design flaw where the desalination units had to be blown down more robustly than anticipated to achieve proper conductivity in the steam cycle. To compound the process control difficulty, the drain material selected by the EPC contractor was PVC, which simply cannot stand elevated temperatures.
PVC is interesting because unlike may materials it's strength simply disappears once the working fluid gets to about 140F. It also shrinks axially when it undergoes heating and cooling cycles. For condensate drains to be routed to sumps which feed an underground network of PVC piping material is certainly a high-risk proposition.
After a bit of excavation and diagnosis, it was confirmed that the process water overflow of the sumps was from collapsed drain lines, piping that pulled away from the sumps, and other similar failures.
The only permanent remedy is to replace the PVC with a material that can withstand condensate temperatures of 212F.
This is an engineering... Read more
There were probably minor savings, amount unknown.
Once repair costs under Warranty considered, this was costly for the Contractor.
In many developing country locations, a recurring problem is the mechanical damage to otherwise properly applied coatings due to handling abuse.
For most plants, structural steel is shop (off site) fabricated, loaded on trucks or ships, and delivered to the construction site for erection. This is an important process because it can become quite expensive and time consuming to field repair coatings. This can be even more true in locations with high humidity because a proper repair must be affected within the coating manufacturers indicated limitations. This is sometimes hard to achieve.
An owner should likewise be concerned because a repaired coating system is never as durable as the original coating. The first photo shows a typical "handling" problem. The subsequent photos show poor repairs and unrepaired damage. Both are so common, it seems normal.
One plant in Asia had structural steel and piping that was so abused with mechanical damage that the plant looked 15 years old even before COD.
Nothing. It costs nothing to handle coated pipe/steel carefully.
If all the repairs were affected, it would have cost several tens of millions of $.
Often field quality suffers from a lack of oversight, quality control, supervision, or owner involvement. Sometimes a contractor and owner set out to assure their interests are protected, but it fails anyway.
Using a large international source inspection firm tends to be where problems arise. Those firms use local inspectors to keep costs down by limiting travel. However, local inspectors are often the same people that visit particular shops and due to familiarity, a relationship develops which compromises the effectiveness of the shop inspection. Instances exist in remote areas where inspectors are relatives of shop owners. The main take-away, is that inspections by ineffective, conflicted, or technically limited personnel with no personal connection to your project is wrought with peril.
The opinion of the author is that if an inspection is worth performing by an owner, send your own people, or an inspector well known and hired directly. It will be more cost than outsourcing with a large international inspection firm, but it will be worth it.
At one facility, the contractor... Read more
$150k +/- and wasted time.