Failed Expansion Bellows
At a new plant with large-scale desalination operations a recurring failure was noted. Dozens, probably hundreds, of failures of 24” rubber expansion bellows occurred due to incorrect installation.
The summary conclusion in this case is that the contractor provided no training or oversight to piping personnel responsible for installing this engineered device.
Operation of the systems created continuous piping vibration (normal levels) and the environment was quite hot, even the working fluid (seawater) was quite warm so the bellows was probably incrementally more relaxed. However, failure was certainly due to flange-to-flange dimension busts, misalignment of bolt holes, out of square flanges, and an assortment of creative abuse.
Where flange-to-flange distances were not to specification (narrow) the bellows nearly universally failed due to bolting impinging on the rubber outer layer of the bellows.
This defect could have easily been spotted by engaged contractor supervision, or by an owner’s representative, but neither addressed the problem which is easy to see. The... Read more
Unknown. Device mortality will be a continual O&M cost for the life of the plant, unless piping changes are made during outages.
GRP Joint Fail
EPR evaluated a very large facility that had one of the world’s largest desalination operations at around 250,000,000 gallons per day. An extraordinary facility in terms of scale and elegance of design. But separately, there were quality concerns. The photos are about 12 months after COD, so the plant was effectively new. For context, the seawater and freshwater ‘loops’ in this plant were miles long and complex configuration of GRP (glass reinforced plastic) commonly known as fiberglass.
GRP is an excellent product but requires attention to detail when installed. Joints need to ‘layed up’ with a carefully proportioned two-part resin over a clean and prepared substrate.
In this plant, chunks of GRP started to appear in the process screens. On further evaluation inside drained circuits and elsewhere via borescope inspection evidence of GRP delamination and shedding at the joints was discovered. If there were a few instances of the problem, it would have been noted and dismissed, but this condition appeared in varying degrees in all the units and interconnecting piping.
The plant... Read more
Unknown. Consider the primary revenue for this plant is water production and a unit outage costs several $X0,000/day. This could get expensive.
Piers, Sort of
Sometimes people ask us how ne plants end up completing so badly. EPR is not typically engaged to develop a well-studied opinion about the details of execution failure, so we tend to stay away from speculation and focus on the task of Verification of Mechanical Completion. However, we can suggest with a high degree of confidence that plants that exit construction/commissioning in poor condition is almost never resulting from engineering failures. Yes, sometimes there are oversights and errors in the plans and specifications, but it is rare enough and usually minor enough to allow us to broadly conclude execution problems are at the site.
This is one example. The drawings indicated a pier design with a spread footing to effectively keep the pier in a fixed position when loaded from pipe stress. However, the site decided to precast piers with a greatly reduced footing area, which contravened the design.
This has resulted in about 300 piers that have settled and been pushed out of plumb by piping forces. Further, the depth of cover is not suitable (<250mm) compared with the original... Read more
Some, but relatively minor. ~$25,000.
The cost of replacement is small compared to the damage to rotating equipment and other components.
"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.
Piping, particularly hot services (Steam, Feedwater, Condensate), are engineered systems. The stresses induced on the piping, fittings, and valves are controlled through purposeful routing, hanger locations, and hangar properties. This is very important to the longevity of system components. Thermal cycles and other transients accumulate stress-induced damage with time leading to failure, if incorrectly installed. Plant reliability and personnel safety are dependent on proper implementation of the engineer's design.
Given their status as “engineered components” it is hard to reconcile the lack of attention-to-detail observed in the installation of supports/hangers in many recently inspected plants. In some cases, the contractors have been so sloppy as to not even finish installing the required supports/hangers.
After a support/hanger is installed, the contractor must also follow up to assure it's correctly setup (commissioned). Usually, this necessitates a QC step to assure the installation is correct, followed by documented verification of the “hot settings”, and then... Read more
Contractor: No savings; hangers usually purchased; lost/not installed.
Contractor: Usually not very costly. Owner: Can be costly, because of the outages caused by even small piping failures/leaks.
Steam Vents at Platform
EPR observed that steam safety valves had lifted at some period in the past during a load transient. The energy from an un-silenced steam release at 1,000F is violent and typically includes a powerful supersonic noise wave. Debris remains impaled on nearby structural steel and equipment from the force of the previous steam discharge.
A serious safety concern is that a personnel access platform is above and adjacent to the five (5) vent stacks. If any personnel would have been located on the platform during a release, they would have no doubt been seriously injured and burned. The owner's operators are exposed to a serious risk until this condition is resolved.
This safety problem persists because of a failure of engineering, piping construction, and the contractors commissioning team to resolve the issue prior to COD.
This is a very dangerous design and all 5 relief valve vents need to be extended above the structure or vented away from the access area.
Minimal cost to extend the vent stacks to a safe elevation.
Owner: Potential O&M personnel injury or fatality with associated costs. Contractor: Minimal cost to extend the vent stacks to a safe elevation.
Dirt... and Fuel Gas
As background, one critical system in a power plant is fuel gas. Typically, every system is cleaned to a condition that is nearly spotless. This is especially true of fuel gas because it feeds the turbines and duct burners. EPR evaluated a plant that was physically very large. The fuel gas header was 1.5+ miles long, inside the plant downstream of the supplier custody-filters. The system changed elevations, had countless fittings, and pipe size changes. Clearly, this is a difficult system configuration to clean well for an inexperienced crew.
Prior to EPR being involved, roughly 50 warranty claims were raised against the EPC contractor that enumerated roughly 300+ failures of valves, flame scanners, regulators, and really anything in the system with a seat or rubber O-ring. The EPC contractor refused to address the issue on-the-whole with a proper RCA (root-cause analysis), instead dealing with each item as if unrelated.
The attached photographs tell the story. This system is so full of dirt and contamination that it's not defensible to indicate proper, or perhaps any, commissioning... Read more
No Savings. Contractor went through "motions" of cleaning system, just didn't!
Just in terms of Owner down-time for needless repairs this is millions of $'s. Parts, labor, etc...
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.
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.