Sometimes good sense isn’t that common. Especially for some contractors.
This is particularly true when it comes to safety gates at the top of access ladders. Contractors in developing regions often have a view that labor is so inexpensive, that making things is cheaper than buying items especially if sourcing from outside the country.
Unfortunately, this ‘handmade’ product is just not of a suitable quality and the hardware provided for spring closures is equally bad. Keep in mind while viewing the photos, that companies make excellent bolt on plastic arms that last a very long time, work without fail, and are easy to install.
The importance of these items cannot be overstated and where they are absent or not working, an operator can be subjected to a nasty fall that could easily be fatal. OSHA is clear that this is not a small matter, thus the CFR 1910.23 standards that govern installation and use of such devices.
While seemingly minor, for owners that are in the process of developing specifications to attach EPC contracts, it is suggested that you pick a nice quality... Read more
None. Probably cost more to fabricate a gate.
This issue is not about cost but prevention of injury and fatalities. Both can have a high financial and moral cost.
While the subject of this post is specifically cable tray fill, the volume of defects is almost limitless in the photos. As a side note, these are new plants and, in some cases, not to COD.
To start, cable trays are usually limited to 40% of cross-sectional area as the maximum allowable cable fill. There are exceptions to this requirement, but those exceptions did not pertain to the subject plants. There are heat dissipation and overloading concerns with trays that have excess fill.
In one of the plants indicated in these photos a 5kV cable tray collapsed during final stretch of commissioning a power block which caused a 3-4 months setback to the block COD schedule. This is a real example where excess load played a factor in a materially costly event.
In addition, the photos show instances where supports are also missing according to NEMA VE-2, which compounds an overloading condition. Further, there are cables hanging over tray rails, missing and defective grounding, bent and sagging tray rungs, no voltage separation, cable transitions with no drop-out fittings, no code... Read more
Minimal cost but takes some planning and trained crews.
In many cases this condition cannot be repaired short of removing all the cables and starting over.
Strangely, at several plants we have reviewed there seems to be at least a few occurrences of structural steel near steam turbines being gouged out by flame-cutting to fit piping or other equipment.
The reason is obvious. It takes no effort to cut a beam compared with the proper approach to ask engineering for a modification.
However, people walk and work on those platforms including often disassembling valves or other items that weigh a bit. Some of the photos show a platform that is failing (sagging) under its own weight.
Overall, not a great present for a contractor to leave an O&M team.
One high-level observation… On projects with an involved and demanding owner, the type of behavior it takes to affect these types of actions is usually not found. Why? Because it is implicitly understood there is personal risk (being fired) for an individual involved in this type of careless activity.
Minimal cost but takes some engineering involvement.
Can be a minor expense to repair, but more important as a safety issue.
To get a quick understanding of an EPC Contractors performance, look at a few cable vaults. Contractors that have reasonably competent labor and supervision can typically plan cable pull work and install the requisite raceway and supports in advance of their work. This is more than a nice-to-have, since it is a code requirement, and with good reason because it is intended to greatly reduce cable damage.
In a vault there are a great many details that need attending, like cable voltage separation, grounding issues, cable bend radiuses, combed/groomed/tied cables, water management, and a variety of meaningful details.
The pictures are from a couple large, NEW, greenfield plants in developing countries that were recently completed. It is possible for an Owner to monitor and insist the pictured results are avoided, but it does take engagement and follow-through.
If you see this condition start to develop on your project, it is a strong forward indicator of broad electrical quality and safety concerns. Often this condition can lead to grounding, relay, intermittent instrument faults... Read more
Condition is very difficult to repair, and expensive after-the-fact because usually cable must be replaced with the coincident outages.
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 activated. 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.
Pipe Rack Bolting
The consequence of structural failure in a power plant is operationally serious and can be life threatening.
When structures are designed for bolted connections usually "high-strength" fasteners are indicated (ASTM A325/A490). If these bolts are not installed properly, per the standard (AISC/RCSC, or other), the joint does not support the loads expected by the engineer. So, when loose bolts are observed in completed facilities, it is alarming because it is an indicator the contractor's bolting program was flawed. Properly installed bolts are verified to be pre-tensioned, which practically eliminates nuts backing off for any reason.
So what constitutes proper pre-tensioning? The code guidelines are specific, however, in simple terms bolts must achieve a certain amount of stretch. The complicating factor is that pre-tensioning varies depending on manufacturing lot, and environmental conditions like moisture because of variable thread friction. This means that daily testing (for each lot) is required to determine a "torque value" for the assembly. If this is not... Read more
Little or none.
Contractor: RCSC arbitration is moderately expensive. Owner: Risks structural failure and personnel injury.
Large (HRSG) equipment erection is about attention to detail, but not overly complex. However, the structural and thermally cyclical nature of these units demands that proper methods and OEM instructions be observed.
In this case, a large new plant with 12 units was inspected one year after COD by EPR. There were so many deficiencies it is clear proper procedures were not followed. For high-strength bolting (ASTM A325/A490) proper pre-tension testing must occur, in addition to proper substrate alignment, thread engagement, and other details. The pertinent requirements, in addition to being code stipulated, were cascaded with clarity in the Contractor’s own specs and procedures, so they should have been followed and QC verified.
For both slip-critical and direct-tension applications bolting was observed to be missing, loose, installed in flame-cut holes, loose plies, and a variety of concerning problems. Over time, this condition will worsen and result in two safety concerns; falling fasteners, and unsafe structures.
Minimal. It takes no more time to pretention bolting by the iron worker. Further, QC checks should have been performed.
Owner: Safety and outage concern. Repairs need to be affected. EPCC: ~$25,000 per unit for equipment, new bolting, and man-lifts.
After noticing an unusual number of severe workmanship issues with grating penetrations, a study was conducted on one portion of a recently visited facility (one power block).
In the subject area, 231 penetrations through grating or deck plate did not conform to the requirements of contractor’s own Structural Erection Procedure, which states that all cuts of 3 grating bearing-bars shall be banded, and further, that field-cut openings shall clear insulation by 1”. The contractor’s own structural drawings also indicate a requirement/detail showing the penetrations of grating and checker plate reinforced with toe plate and banding.
Of the 231 inspections, 39 were missing banding, 174 had no toe plate, 10 did not meet the required insulation clearance, and 8 open holes were left in the grating. In total, roughly 100% of the penetrations were out of compliance with normal practice and the contractor’s criteria indicated above.
More concerning, is that the workmanship is so poor in some instances that almost none of the bearing-bars remain intact leaving the structural integrity of the... Read more
Labor/Supervision savings and probably some material.
Contractor: Some material expense and labor. Scaffold in some locations perhaps. Owner: Risks injuring O&M personnel or worse.
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.