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ISSUED November 1, 2002


Victor Singer

I am Victor Singer, and I am speaking today only in my own behalf, though I am Chairman of the NC County Planning Board, a member of several other official entities, and a long time director of Civic League for NC County. I am a retired engineer and rocket scientist, with over a third of a century of design and fabrication experience on high performance pressure vessels for rocket motor applications. I have dozens of published technical papers and issued patents, and several awards and commendations at State, national and international levels. I'm going to tell you alot that most of you never wanted to know about structural integrity of pressure vessels, and why not.

I appreciate how easily my remarks could be dismissed as imaginary horribles in the mind of somebody experienced with much lower safety factors than are typical of commercial practices, with structural materials of far greater sensitivity to behaviors that just don't happen in the REAL world, with circumstances where the margin between a successful flight and a fireball in the sky is infinitesimally small, and with no vital concern about the costs of academic exercises and fishing expeditions. What I ask is that you concentrate on those attributes of the Motiva boilers that are far from the focal points of relevant boiler codes and typical conditions of service, thereby justifying unusual regulatory practices. I ask that you assure reviews of the key technical judgments by people experienced not only with prior successes, but also with prior failures. I ask for all of that at the outset of the repair and rehabilitation period, to minimize the likelihood of exploring the same technical territory later, in a coroner's inquest.

This hearing is about a 90 day operating permit renewable for one additional 90 day period, issued on Motiva's application. The permit authorizes operation of four large portable package boilers, two for the refinery's 600 psig steam system and the other two for the 175 psig system, to satisfy a need to boil more than 800,000 lbs of water per hour. Were these to be the entire steam supply, the refinery would operate at a capacity factor no greater than 41%. The temporary boilers will make it possible for Motiva to ". . .thoroughly inspect and make any REQUIRED repairs to impacted equipment. . ." (emphasis added by capitalization)

Motiva acknowledges that its demineralized boiler feed water system somehow got so severely contaminated with acid that it ". . .caused two of the refinery's four boilers to fail and shut down, and caused a significant leak in another. . ." and also impacted the fourth boiler and other operating equipment.

The application does not disclose how low a pH was reached and the duration of the exposure. We are told only that operation of the boilers continued, at pressures possibly as high as the 1250 psig rated pressures shown in the permit, and temperatures as high as 900 degF, during the exposure to feedwater with a high hydrogen ion concentration. It isn't possible on that scant information to judge how much opportunity existed for how long for how much hydrogen to diffuse into the steels of undefined chemistry, melt and fabrication practice, though it is well known that hydrogen charging embrittles many steel alloys. Indeed, hydrogen is so bad an actor that when acid etching is used at ambient pressure and only moderately elevated temperatures in preparation for plating, the plated parts are often baked to get rid of diffused hydrogen.

The application does not disclose the extent that joint configurations in the existing structures provide opportunities for crevice corrosion, an insidious mechanism because even with a benign bulk environment, aggressive environments can form and persist within crevices.

The application does not disclose the extent that the various steels in the installations might have been susceptible to stress corrosion crack initiation and growth during the unplanned low pH exposure.

The application doesn't address structural adequacy of the inspected and rehabilitated permanent installation at all, either before or after completion of the rehabilitation activity. Nor does it provide a description of what will be sought in the "thorough inspection" of the impacted equipment. Nor does it say what the basis will be for establishing what repairs will be "required," or by whom.

Most boilers in operation today are not large enough to boil several hundred thousand pounds of water per hour at 1250 psig and 900 degF. The Motiva boilers are a bit removed from the focal point of the ASME pressure vessel code. The damage inflicted on the Motiva boilers may be a bit worse than the usual service life experience of boilers closer to that focal point. Therefore unusual dispositions may be quite appropriate for the Motiva boilers.

By addressing a need for as much as six months of repair and rehabilitation, the application acknowledges that the boilers are in less than pristine condition. The missing disclosures indicate that the applicant seeks escape from the burden of proving that the installation can be operated safely after rehabilitation. In other words, the applicant wants to avoid needing to prove beyond a reasonable doubt, or beyond the shadow of a doubt, or beyond whatever standard of assurance DNREC may prescribe, that the potentials for a bad outcome are no more than imaginary horribles. Instead, the applicant seems to regard the grant of permission to proceed as a government obligation unless government can prove that a bad outcome can be expected.

At this point, let me define what I mean by a bad outcome. I regard "leak-before-burst [LBB] capability" as a loosely defined boundary between ductile and brittle behavior. A vessel has LBB capability when it can withstand the operating pressure and temperature environment even with a crack completely thru its wall, with a length one to two times the wall thickness. With such a crack, the vessel leaks, but the crack doesn't propagate. Thus characterized, the technical literature has addressed LBB capability many times, both before and after several of my own papers, starting in 1969.

I would be surprised by a finding that the boiler tubes and the in-plant piping at Motiva do not have LBB capability even after substantial hydrogen infusion. I would expect that if a boiler tube fractured, even pneumatically, a leak would develop but the fracture wouldn't run. Anybody closer than the steam cloud that typically develops - - I've seen that several times - - could be injured or killed, but only water is released. The environmental consequence is a bit of rain. I DON'T see that as a bad outcome.

But I would be surprised if the boiler drum had LBB capability even without hydrogen infusion. Therefore, my focus is on the boiler drum, not because I think the potential for failure of a boiler tube is small, but because I think the CONSEQUENCES of failure of a boiler drum present far greater risk to life, limb, property and the environment. If a boiler drum fractures pneumatically, it probably shatters. Pieces fly, sometimes quite far. THAT'S a bad outcome. And the refinery shuts down suddenly.

I appreciate that structural adequacy and boiler safety are more properly within the jurisdiction of the Division of Boiler Safety rather than DNREC. A pneumatic burst of one of the boiler drums, taking the lives of nearby personnel and destroying a good bit of property, might not be DNREC's primary concerns. But the potential for environmental damage from sudden loss of a large fraction of the refinery's steam supply IS a DNREC concern.

Clearly, the application is based on the tacit assumption that the imposed damage is repairable. I ask for a statement confirming that the judgment is Motiva's alone, and that no arm of government is bound by it, if indeed those are facts. And if not, I ask for a definition of the extent that the State is bound.

Also, since the permanent installation is now in less than pristine condition, there needs to be an address to how close to a pristine condition the repair activity will be configured to achieve, and how close to a pristine condition will be necessary for lawful operation of the repaired permanent installation.

On November 2 by e-mail to the addresses on the relevant notices, I asked DNREC to address these issues. No response was forthcoming until I approached the Secretary's office on Nov 21, and even then, only a partial response. Earlier, at mid November, after reading the application and the permit at DNREC offices, I inquired at the Division of Boiler Safety, and got immediate attention. I was advised that several boiler tubes have been replaced, that before being returned to temporary service, each boiler was hydrotested at 150% of the maximum operating pressure, that the boilers are to be taken out of service one at a time for inspection and rehabilitation, that an inspection protocol is being devised, and that after the inspection and rehabilitation are completed, each boiler in turn will again be hydrotested at 150% of the maximum operating pressure.

Hydrotest is pressurization using water, to a level substantially above the service pressure level. Obviously, hydrotest risks the survival of the vessel. But because water is nearly incompressible, the likelihood that the vessel will shatter, should a burst occur, is much diminished in comparison with a pneumatic burst at the same pressure level. Shattering is the usual pneumatic burst mode because in gaseous media, large volume changes are concurrent with small pressure changes. The fracture propagates faster than the pressure diminishes. Though losing a vessel in hydrotest is a great burden, it's far worse to lose one in a pneumatic burst.

I acknowledge far lesser faith in structural adequacy demonstrations based on the efficacy of nondestructive examination techniques, one at a time or in combination, than. by hydrotest. I am convinced by personal experiences going back about 40 years that remarkably small flaws and cracks can sometimes be found when fortuitously located, and far larger flaws and cracks can be missed when circumstances are less than fortuitous.

It's tempting to believe that today's inspection practices can't miss anything. Asking the inspection folks how small a flaw they can find gets an impressive and knowledgeable answer. But that's not the right question. What we need to know is how large a flaw they can miss. They can't answer because they don't know.

So NASA investigated experimentally, and quantified the assessment I offered a moment ago. A NASA document, NHB 8071.1 "Fracture Control Requirements for Payloads Using the National Space Transportation System," shows flaw size and location combinations that particular inspection protocols could be expected to find with a reliability of 90% at a 95% confidence level. It shows that under some circumstances, there is a 10% chance of missing a crack completely thru a vessel wall. And it endorses using the hydrotest as a sure indicator of the absence of flaws or cracks large enough to govern structural behavior at the hydrotest pressure. If Delaware believes that the upcoming inspections at Motiva will be more effective than what NASA demands for flights on Shuttle, Delaware should teach the course.

For the Motiva boilers, the Division of Boiler Safety could well be confronting situations that differ in important respects from what the Boiler Code was designed to deal with. It is conceivable also that the Division of Boiler Safety doesn't have the legal muscle to demand what may be technically appropriate to the present problems. DNREC, on the other hand, may well have sufficient muscle to deal with the environmental implications, but lacks technical knowhow to deal even with elementary boiler safety issues. Thus DNREC and the Division of Boiler Safety need to coordinate their efforts carefully and thoroughly. Among the issues needing attention are:

  • How will we assure that the burden of proof is Motiva's, not the government's?

  • Could DNREC find that continued operation of the boilers despite the additional public and environmental risk occasioned by the October event could not possibly be among Motiva's rights under the grandfather provisions of the 1971 Coastal Zone Act, and that therefore the rehabilitation protocol is subject to the compensating enhancement provisions of the Coastal Zone Regulation?

  • Among those already involved, who is competent to make the needed critical judgments about the potentials for a bad outcome that I've listed, or to recognize others that I haven't noticed? If nobody, who if anyone will seek out and engage such consultants?

  • Who among us is competent to make the judgment that testing of generically similar materials - - or even samples from the actual structures - - after simulations of the unplanned environments will or will not be important elements in a determination that safe operation of the less-than-pristine boilers will be possible? If nobody, what then?

  • Who will cast the judgment that it is sufficient to perform a hydrotest at 150% of the maximum expected operating pressure on vessels of hydrogen-charged steels, with whatever flaws escape all the detection efforts, including those missed initially and those created before, during and since the October incident? And who will cast the judgment of how long an interval will be the maximum allowed before the next hydrotest, to accommodate the potential for further crack growth under service conditions?

  • If 150% is sufficient, would hydrotest at more than 150% enable a longer between-hydrotests interval, or at less than 150% for a shorter interval?

  • Will a requirement be imposed that each boiler be equipped with a system for continuous monitoring of boiler feed water chemistry, or at least its pH, with recorder and alarm features?

  • Are the portable boilers so equipped?

Victor Singer

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