QC Inspection

Flex-abuse


Where labor and supervision are less skilled, electrical installation quality can be very poor.  However, keep in mind that all EPC contracts have codes, standards, and often owner specifications that provide overlapping requirements that mandate this be done properly and that it is verified by contractor QC personnel.  But, to no avail.

One aspect seen on almost every developing country project, is the abuse of liquid-tight metal flex.  Please note the photos are from NEW plants, and alarmingly in some cases not even to COD.

Flex is designed to be used in locations where there is differential movement between a piece of equipment and conduit feeding a circuit to the equipment.  Flex is not intended to be a shortcut device where an electrician does not have the skill to make proper conduit bends. 

Far too often, flex is used where it should not be. To put an approximate number on it, easily 50% of flex use should not exist.

In other cases, the proper fittings are not provided on each end, grounding continuity is not assured, excessive flex length is used, leaky installation is... Read more

Contractor Savings

Costs somewhat more to perform correctly.

Repair Costs

The life-cycle ramifications for owners can be significant due to water damage of electrical and I&C devices leading to intermittent system ghost trips and failures.

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

Contractor Savings

None.

Repair Costs

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

Contractor Savings

None.

Repair Costs

Unknown.  Consider the primary revenue for this plant is water production and a unit outage costs several $X0,000/day.  This could get expensive.

RTV to Fit


EPR has been in many greenfield plants just prior, or just after COD.  Basically, new plants.

Without hesitation, liquid-tight flexible metal conduit (flex) is abused and mis-installed possibly more than any other heavy industrial components, especially in developing regions.

Often labor is not given proper instruction and almost never the proper tools to install this system correctly.  This results in fittings that are, at best, hand tight.  Consequently, there are grounding concerns even in the best cases where flex appears to be installed correctly, assuming an internally grounded flex is used and the correct fittings.  In most cases leaks occur and instead of tightening the fittings, a big smear of RTV is used as a seal.  This usually does not work and creates a mess of the install.

In some plants, we have run studies in limited areas intending to be ‘representative’ and found >95% of flex fittings are loose. 

For Owners concerned about the longer-term implications of moisture in electrical and instrument equipment, this is not a positive finding.

Contractor Savings

None.  Probably costs more to perform incorrectly.

Repair Costs

The cost of repair would seem manageable, but this defect is so pervasive in most plants that cost can be material.  However, the O&M cost for an Owner can be even higher due to device mortality.

Uncured Coatings


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 topcoat 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

Contractor Savings

None.

Repair Costs

Colossal.  Left unrepaired...

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 trash being embedded at the bonding joint, among other concerns.

One certainty, there was no engaged contractor QC or owner involvement.

Contractor Savings

Essentially none...

Repair Costs

In the future, the piers will need to be re-grouted as routine maintenance.  Unknown cost.

Settle for More!


In nearly every developing country location, plants evaluated by EPR have exhibited very poor performance of soil compaction, especially related to area paving.

At one facility, a more extensive review was conducted because significant settling was evident in dozens of areas. In the first photo, not only is the area paving soil consolidating, so is the soil below the pipe support foundation, which rendered the support ineffectual.  Some of the other pictures show images taken from a borescope beneath a slab where the soil had consolidated in the 12 months after the slab was poured. The findings included exposed rebar, construction debris, form work, voids, unconsolidated concrete, and improper slab thickness/finish. In all, technically nothing about the installation was acceptable.

In the last photo, a small crew can be observed preparing soil for finish grade.  It exhibits well the nature of the problem.  Simply, the crew did not have the tools or knowledge to perform the work correctly. QC was also not likely to be involved to verify soil density.  However, it's a safe bet the QC... Read more

Contractor Savings

Minimal.

Repair Costs

Owner will live with poor conditions and possible operator injury.  Ongoing O&M cost.

Mechanical Damage


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.

Contractor Savings

Nothing.  It costs nothing to handle coated pipe/steel carefully.

Repair Costs

If all the repairs were affected, it would have cost several tens of millions of $.

Inspection Futility


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

Contractor Savings

None.

Repair Costs

$150k +/- and wasted time.

Getting Touchy


Coatings are typically shop applied and touched up in the field.  On a large power station, there is considerable touch-up and it must be done correctly.

Briefly, as mentioned elsewhere in this Blog, coatings are not "paint", they are an engineered product that requires skilled personnel to apply properly.  In this case there are three coats in the system.  A zinc primer, epoxy mid-coat, followed by a urethane topcoat.  Details... No coating will stick to steel substrate that is dirty, too smooth, or otherwise not prepared to the coating manufacturers requirements.  An epoxy mid-coat sticks well to a zinc primer but does not stick to a urethane topcoat.  If epoxy is left without a urethane topcoat, it deteriorates from UV.  Urethane in most case needs to be applied over epoxy.

So, if a repair needs to be made, the existing paint needs to be taken off down to the primer, or mid-coat, depending on the damage.  However, epoxy (mid-coat) cannot be "slapped on" as to overlap onto existing urethane.  It will not stick.  Also, coatings cannot be applied over corrosion or dirt; seems obvious... ... Read more

Contractor Savings

No savings.

Repair Costs

Varies by plant, but to re-perform is significant.  If unrepaired, O&M is constantly painting, or lets plant rust.

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