Amy Sebring: Welcome to the EIIP Virtual Classroom! Amy Sebring: One quick note about any URLs that may be used in the session; they are live links and you can click on them and view the referenced site in your browser window. Amy Sebring: Subsequent "slides" may display behind your chat window, so you may need to bring the browser window forward. Amy Sebring: Background information for today's session may be found at http://www.emforum.org/vclass/990908.htm . Amy Sebring: We will have a presentation for about thirty minutes, and then have audience Q&A for the last thirty minutes. We will review the instructions for Q&A as we are about to begin that portion. Amy Sebring: We are pleased to welcome Dr. Marc Levitan, Acting Director of the Hurricane Center at Louisiana State University (LSU) and Associate Professor of Civil Engineering. Amy Sebring: Dr. Levitan has been actively engaged in wind engineering research, practice, and teaching for the past 15 years. His primary research focus is in the fields of wind loading on structures, wind damage assessment, wind damage mitigation, and hurricane sheltering and evacuation issues. Amy Sebring: A couple of photos of him may be found on "Dr. Marc's Wind Engineering Page" at http://www.geol.lsu.edu/workshop/students/levitan/index.html Amy Sebring: Marc is going to tell us about his paper "Are Chemical Plants at Risk from Hurricane Winds?" A copy of the full paper may be downloaded from the Hurricane and Hazards Internet Conference at http://hurricane.lsu.edu/internetconf.htm . Amy Sebring: Marc, thank you very much for joining us today. Marc Levitan: Thank you Amy. Glad to be here. Marc Levitan: Many places on the US coastline are home to large concentrations of chemical/petrochemical/agrichemical plants. Areas such as Corpus Christi and Houston TX, Lake Charles, New Orleans, and Baton Rouge Louisiana, the Mississippi and New Jersey coasts, among others. Marc Levitan: Are these plants at risk from hurricane winds? Marc Levitan: These plants are filled with complex structures, many of which there are no wind loading standards available for. Figure wind1 shows a typical plant, with process structures on the left and a tank farm on the right (photo credit: unknown). Marc Levitan: http://www.emforum.org/vclass/wind1.jpg Marc Levitan: There two biggest potential impacts from hurricane wind damage are release of hazardous materials into the environment and the economic impact of repairing damaged structures, including loss of production while the repairs are underway. Marc Levitan: Hurricane preparedness procedures that lessen one of the potential impacts often have a negative effect on the other potential impact. Consider the common case of a steel storage tank. Marc Levitan: These are very thin shell structures. Empty, they can be easily damaged or destroyed by moderate hurricane wind speeds, like squeezing an empty soda can between two fingers. A full tank is much stronger, much like an unopened soda can. Marc Levitan: Hurricane preparedness procedures often call for tanks to be filled. This significantly increases the wind resistance of the tank, thereby reducing the potential that a release will occur. However, in the event of damage, the entire contents of a full could potentially be released. Marc Levitan: When questioned about the wind threat, a common response is 'Our facility is designed to withstand hurricane winds.' Marc Levitan: The general attitude seems to be that expected wind damage would be minor, such as damage to storage trailers, sheet metal roofing and siding failures, minor debris damage, etc. Marc Levitan: The idea that major process structure, pipe rack, or other engineered structure could suffer significant wind damage or even collapse does not appear to be widely considered. Marc Levitan: IS THERE A FALSE SENSE OF SECURITY? Marc Levitan: One reason for this relative lack of concern is the perception that industry-wide, the various structures found in the process industries do not fail in high winds, so there must not be much of a problem. Marc Levitan: With the exception of the past few years, the Atlantic basin has enjoyed nearly three decades of relative calm, experiencing less frequent and intense tropical storms and hurricanes than the long term average. Marc Levitan: Institutional memory also plays a part in this sense of security. Most of the plants have experienced several minor hurricanes or tropical storms in the past 30 years and come through with fairly minor damage, which has served to build up confidence in the ability of the structures to withstand hurricanes. Marc Levitan: Major hurricanes are defined as Category 3 and above. Very few major hurricanes have hit areas with chemical plants. Hurricane Andrew fortunately came ashore between New Orleans and Lafayette, skirting by the concentration of plants on the lower Mississippi River. Marc Levitan: Hurricane Andrew did however take a large toll in offshore structures. Nearly 300 manned and unmanned platforms were damaged or destroyed due to the combined effects of wind and waves, including some newer structures. Marc Levitan: A refinery on the island of St. Croix suffered serious damage during the passage of Category 4 Hurricane Hugo in 1989. In addition to other damage, several petroleum storage tanks were damaged which led to a significant oil spill. Marc Levitan: Hurricane Alicia in 1983 in the Houston area did some damage to area chemical and petrochemical plants. Thus recent history demonstrates the potential for significant damage to chemical and petrochemical structures in Category 3 and stronger hurricanes. Marc Levitan: ARE THE STRUCTURES TRULY DESIGNED FOR HURRICANE WIND SPEEDS? Marc Levitan: A commonly held perception is that if an engineered structure is "designed to code" then it will withstand all but perhaps the most intense hurricane with very minimal damage. Marc Levitan: Current design standards have significant limitations that are not always appreciated. They are primarily life safety codes. Factors such as environmental damage and economic impact are not considered. Additionally, codes and standards do not address some of the structure types most commonly found in chemical plants. Marc Levitan: The fact that many of the structures found in the plants are not addressed by building codes and standards has led to wide variations in design procedures and estimates of wind loads, even if the wind speed is specified. Most firms involved in the design or operation of chemical and petrochemical facilities developed their own wind loading guidelines. Marc Levitan: Wind loads on open frame structures are not addressed by codes. These are highly complex structures, supporting vessels, reactors, piping, and other equipment. An example of this type of structure is shown in Figure wind2. Marc Levitan: http://www.emforum.org/vclass/wind2.jpg Marc Levitan: Wind loads on a sample open frame structure were computed using 13 design guides from large petrochemical producers and engineering/construction firms. A wind speed of 96 mph was used in all for all calculations. The results (listed below in thousands of pounds) varied from 90,000 to 182,000, more than a factor of 2. Marc Levitan: 90 112 116 116 120 129 141 141 148 154 160 162 182 Marc Levitan: average = 136 Marc Levitan: The implications of the wide ranging variations are significant. If a plant specified that this structure be designed to ASCE 7 wind speeds, one firm would be designing for a wind force as low as 90 kips, while another would be designing for as much as 182 kips (1 kip=1000 pounds). Marc Levitan: The best estimate of the actual wind load 147 kips. While many design guides yielded results in this ballpark or more conservative, five out of 13 estimated wind loads roughly 20-40% too low. Marc Levitan: Pipe rack structures are very common in plants, supporting the pipes that connect the various processes throughout the plant (see Figure wind3). Marc Levitan: http://www.emforum.org/vclass/wind3.jpg Marc Levitan: Results of a similar comparison study for pipe racks yielded much greater variations, as much as 400% from the lowest estimate to the highest. Marc Levitan: SUMMARY Marc Levitan: There have been very few significant hurricanes in recent decades to strike chemical and petrochemical plants. Some wind damage has been seen to occur during Category 3 and larger storms, but this information is not widely known. Marc Levitan: The experience of relatively minor damage to plants during Category 1 storms in this period has perhaps lulled many into a false sense of security. Marc Levitan: Limitations of the codes and standards under which they plants were designed are not fully appreciated. These factors have led to what appears to be an unfounded expectation that significant damage due to high winds is very unlikely. Marc Levitan: Finally, this is occurring at a time of increasing wind risk, due to long term climactic trends of increasing Atlantic hurricane activity and the potential impact of global climate change. Marc Levitan: end Amy Sebring: Thank you Marc. We will now take questions from the audience. If you have a question or comment, please indicate by inputting a question mark (?) to the chat screen. Then compose your question but hold it until you are recognized; then hit Enter or Send. Amy Sebring: First question please? Amy Sebring: While folks are thinking ... Amy Sebring: I have a question ... Amy Sebring: I understand from a previous wind presentation ... Amy Sebring: that duration of the winds have almost an unknown impact on loading ... Amy Sebring: did you calculations factor in wind duration? Marc Levitan: The calculations shown were for the peak gust. ... Marc Levitan: Some types of construction are sensitive to the duration of the load... Russell Coile: ? Marc Levitan: while other types are not. The structures in an industrial plant... Marc Levitan: are typically steel construction (with some concrete). Marc Levitan: These structure types are not that susceptible to load duration. Marc Levitan: Wood construction, on the other hand, is much more sensitive to the duration of loading. Amy Sebring: Russell please. Russell Coile: Isn't the situation possibly even bleaker? During Hurricane Andrew, apparently every.. Russell Coile: anemometer in the hurricane are blew over, etc including the Weather Service. No one, Russell Coile: really knows the maximum gust speeds - perhaps more than 150 mph. Marc Levitan: Good question Russell. Amy Sebring: ? Terry Storer: ? Marc Levitan: In Florida, there is still a debate raging... erwin prater: ? Marc Levitan: between meteorologists and wind engineers over... Marc Levitan: what the surface wind speeds were. However, it appears Marc Levitan: that although in some isolated areas there were gusts in the 150 mph+ range... Marc Levitan: most of the areas saw substantially less. Also... Marc Levitan: There was a problem with the South Florida code at the time, ... Marc Levitan: the specified wind speed was 120 mph, but that was for a sustained wind Marc Levitan: they didn't have a factor to account for peak gusts. The current Marc Levitan: wind speed design map for south FL specifies peak gust speeds Marc Levitan: of 140-150 mph, depending on location. Amy Sebring: Although you may not have been looking for it, did you find any kind of correlation between conservative design and hazard posed by the contents? Or are the same "specs" used regardless of contents? Marc Levitan: I have not looked into that. Others in our university and a group at Tulane are now beginning to address those type of questions. Amy Sebring: Terry please Terry Storer: Is there any factor to account for "dirty wind", those winds with all kinds of foreign objects being blown about ? It would seem that what is being blown about could significantly effect structural integrity. Russell Coile: ? Marc Levitan: Another excellent question. Marc Levitan: For industrial/petrochemical type structures, the ... Marc Levitan: debris field would typically include metal siding... Marc Levitan: and perhaps some other items from adjacent areas... Marc Levitan: Plans typically. do a good job of picking up and tying down items Marc Levitan: which could present a significant debris potential. Also Marc Levitan: the nature of the steel structures is that they are not that Marc Levitan: susceptible to small debris, like residential or light commercial construction is. Amy Sebring: Erwin please. Amy Sebring: Erwin, please pop your question in when ready. Amy Sebring: Russell please. Russell Coile: Do you Civil Engineers have all the appropriate wind tunnel facilities you need, or ... erwin prater: I was wondering, Marc, if you've had a chance to look at the effects of hurricane Camille (1969, I believe) in Baton Rouge/New Orleans. I was wondering how the chemical plants faired during that storm. Russell Coile: do you need both BIG and armor-plated, so to speak tunnels for possible damage? Amy Sebring: Take either one Marc please. Marc Levitan: Erwin, I don't think Camille caused much damage in N.O/B.R. to plants, or if so, I haven't heard about it. erwin prater: ? Terry Storer: ? Amy Sebring: ? Marc Levitan: Russell-the type of wind tunnel testing needed right now is very fundamental... Marc Levitan: We (the wind engineering community) have studied wind loads on houses and typical commercial construction... Marc Levitan: for the past 30 years. We understand the aerodynamics of these structures fairly well. Marc Levitan: No one has looked into the wind loads on industrial structures... Marc Levitan: in a systematic way yet, just studied individual, specific buildings Marc Levitan: for industrial clients. Marc Levitan: Here at LSU Marc Levitan: we have had some basic testing on open frame and pipe rack Marc Levitan: structures under way for the past 3 years, and are now building a larger wind tunnel Marc Levitan: to handle more detailed, larger models. Amy Sebring: Erwin please erwin prater: I wasn't sure...that was well before my time in Louisiana. Amy had a question about conservative design and the type of chemicals stored. The Army stores nerve agents in underground bunkers, partially for this reason. Amy Sebring: Terry please. Terry Storer: Does the age of the structure provide any change in the threat profile ? Marc Levitan: It can... Marc Levitan: Plants are typically very caustic environments... Marc Levitan: Corrosion and other degradation of structural integrity Marc Levitan: are very likely if the structures are not adequately maintained. Marc Levitan: Also... Marc Levitan: in areas such as Louisiana, we have had much coastal land loss Marc Levitan: plants built 50 years ago were perhaps 30 miles from the coast, but are in some cases Marc Levitan: much closer than that now. Since the winds decrease rapidly with passage over land, this Marc Levitan: land loss in effect increases the wind speed for the same storm at the same location. Amy Sebring: Are there specific failure points, welds, bolts, etc.? Marc Levitan: Yes. Marc Levitan: Generally (true for almost any type of failure due to any cause) ... Russell Coile: ? Marc Levitan: failures occur at connections Marc Levitan: or due to buckling. Amy Sebring: Russell please. Russell Coile: Back to wind tunnels - Isn't NASA always talking about "technology transfer", partner. Marc Levitan: Yes. We hope to use some NASA facilities when we need to test larger scale models... Russell Coile: ships with industry & universities, blah, blah - and the US Air Force, also. Can you ... Russell Coile: use their slow speed facilities? Marc Levitan: but we aren't at that point yet. Amy Sebring: We have time for one or two more questions? Amy Sebring: I would like to ask ... Marc Levitan: Our wind tunnels at LSU are capable of wind speeds of approx. 120 mph. Amy Sebring: what recommendation would you make to a local emergency manager or LEPC member? Amy Sebring: What questions should they be asking? Marc Levitan: To work closely with their local plant managers... Marc Levitan: To find out the types of chemicals used in order to be prepared... Marc Levitan: and to ask some questions about what design criteria were used Marc Levitan: for the structures. Amy Sebring: Finally, you have alluded to your ongoing research on this topic; is there a specific direction you are taking? Marc Levitan: We have several projects ongoing in our wind tunnels, but... Marc Levitan: we also hope to expand our research into computational fluid mechanics Marc Levitan: approaches, and would also like to gather data on past failures Marc Levitan: and do field analysis of future wind-induced failures... Marc Levitan: REQUEST-if anyone has experience or knowledge of wind damage in Marc Levitan: a plant, please let me know so we can investigate and use this 'full scale data'... Marc Levitan: to verify the data collected in wind tunnel experiments. Amy Sebring: Marc, would you like to put up your email address? Marc Levitan: levitan@eng.lsu.edu Amy Sebring: Thank you very much Marc, and thank you audience. We will have a text transcript posted later today, and a reformatted version early next week. You can access these via the Transcripts link under Quick Picks on our home page. Marc Levitan: I would also like to... Amy Sebring: please go ahead. Marc Levitan: mention the home page address of our LSU Hurricane Center... Marc Levitan: hurricane.lsu.edu This site Amy Sebring: http://www.hurricane.lsu.edu Marc Levitan: contains links to all of the hurricane-related research being Marc Levitan: conducted at LSU. It is still being developed, but it already Marc Levitan: contains useful and useable information, such as the Marc Levitan: Hurricanes and Chemical Hazards internet conference sponsored by EIIP. Amy Sebring: Thanks, the link is also on the background page for today. Amy Sebring: Our time is about up, but before we adjourn, Ava will give us a heads up on our upcoming events. Ava? Avagene Moore: Thank you, Amy. And thank you, Marc, for your presentation. Excellent discussion, Marc, and good questions from the audience ... Avagene Moore: Next Tuesday, 9/14, 12 Noon EDT, our Round Table discussion is hosted by the FEMA Community & Family Preparedness program with Kellye Junchaya serving as the moderator. The topic will be CERT Programs with Sam Isenberg as our guest. Avagene Moore: On Wednesday, 9/15, 12 Noon EDT, we will have a Panel Discussion in the Virtual Forum. The panelists will be folks involved in the Gulf States Shelter Study. Should be very interesting. Make plans to join us for both sessions next week. Avagene Moore: That's all for now, Amy. Amy Sebring: Thank you Ava. We will adjourn the session but you are invited to join us back in the Lobby room for a few more minutes of open discussion and to thank our guest.