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BP Explosion
6

BP Explosion

RE: BP Explosion

Was this a butane or pentane/hexane isomerization unit?

Vita sine litteris mors est.

RE: BP Explosion

(OP)
Rich2001,

I haven’t heard anything about the specific type process unit involved.  But talking to a buddy that has worked at the plant he said that he has heard from several sources that stared with problems with a flare stack.  This is also mentioned in the side bar of the following.   All dead are contractors.

http://www.chron.com/cs/CDA/ssistory.mpl/topstory/3100123#

RE: BP Explosion

This morning I heard that it was a raffinate leak that set off the explosion. The unit was in start up. The contractor trailers were still on the unit site and were destroyed.

RE: BP Explosion

Weren't the contractor trailers (where most were injured or killed) used for construction on a different unit?  Weren't the trailers coincidentally in the path of the blast?  Some facts should be coming out soon.  Consider waiting for the formal report instead of believing that the newspaper or TV reporters understand the details.

John

RE: BP Explosion

It's astonishing how many errors TV reporters manage to put in a 1 minute news item when it comes to refining/chemical. You discover that only when you see your own plant on tv (I once saw a major distillation tower being erected and laughed my @$$ off when I heard the comments).

RE: BP Explosion

Quote:

Witness Evidence Points to Atmospheric Vent Stack in BP Texas City Refinery Explosion

Witnesses describe the release of hydrocarbon liquid and vapor from an approximately 100-foot tall atmospheric vent stack located in the northwest corner of the isomerization unit. They observed this liquid and vapor falling toward the ground seconds before a powerful explosion. At the time of the explosion, the raffinate splitter subunit was being restarted after a maintenance turnaround on the isomerization unit. Based on our review of plant schematic diagrams, the atmospheric vent stack was connected to pressure relief devices for the raffinate splitter distillation column. Witness evidence points to possible ignition sources on the ground near the vent stack.

from http://www.csb.gov/index.cfm?folder=news_releases&page=news&NEWS_ID=215

Vita sine litteris mors est.

RE: BP Explosion

According Huston Chronicle
 “BP spokesman Bill Stephens Friday said the fire, which erupted at 2:45 p.m. Tuesday from a three-fourth inch bleeder valve on a furnace line in the plant's isomerization unit, was quickly put out with a hand-held fire extinguisher.
``We will look at it with all the other information and see if there is any connection,'' Stephens said.  ``Fires are not supposed to happen.''
The seconds-long blaze was attributed to a missing valve plug.
The explosion at the 1,200-acre plant bordering Texas 146 occurred as workers attempted to restart the refinery's isomerization unit after a two-week shutdown for maintenance. "This is one of the most vulnerable times," said John Miles, regional director for the U.S. Occupational Safety and Health Administration.”

RE: BP Explosion

"Fires are not supposed to happen..." - that's a beautiful blinding flash of the obvious, spokesman, I would rather tend to think that these are the kinds of fires you'd rather not want to put out before cutting out the furnace feed.

RE: BP Explosion

I don't know how many of those in the Petroleum Refining industry are following this closely, but this is going to be an industry-changing episode.

Laid on my desk this week was a safety bulletin outlining my company's plans to reduce the risk of temporary trailers/structures used in the plant confines.

I have heard (rumor mill only) that OSHA (?) will be developing a facility siting requirement - dealing with restrictions for trailers/structures within blast overpressure zones - as a result of the explosion at BP.

Anyone else have similar comments?

~NiM

RE: BP Explosion

Currently OSHA's Process Safety Information requirements include "Siting Factors". In our HAZOPs we interpret this to include a walk around the site to identify such hazards as barriers to fast egress and trailers that don't have to be so close to operating units.

HAZOP at www.curryhydrocarbons.ca

RE: BP Explosion

Yesterday Shell were fined £900,000 for the deaths of two guys on the Brent Bravo in Spetember 2003...I wonder what BP's fine will run to for this refinery incident?

RE: BP Explosion

BP has issued a preliminary report and press release regarding the ISOM unit explosion.  You can get the report here:

http://bpresponse.org/external/index.cfm?cid=946

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

RE: BP Explosion

Ouch. The F-20 revamp and connection to the flare project sounds like the medium priority high cost project that never gets approved but never gets cancelled either... until the thing blows itself up. I guess every refinery has their F-20 equivalent (at least we did). Why can't we learn without this kind of tragedies...

RE: BP Explosion

Refinery and chemical plants typically lack the equipment protection requirements that are applied to an offshore facility.  In addition to the DCS level controls, every offshore vessel requires a seperate high level shutdown system and valve that would stop the liquid inflow.  Perhaps the refining and petrochemical groups within API etc. should incorporate similar requirements as described in API RP 14C for the offshore industry.

BTW, maintenance bypasses might still permit such operator errors but not without multiple alarms.  Normally the shutdown system alarms and indications are still active even if the shutdown is bypassed.  No startup bypass would typically apply to high level.  A startup bypass for the low level would likely become active once the level was established.

John

RE: BP Explosion

Just out of curiosity, the link in Rich2001's post suggests that both BP and the union are carrying out spearate accident investigations (whihc will possibly come to two different conclusions!); is there no US equivalent of the UK's HSE, a government agency with responsibilty for Health & Safety at work in the UK?  The HSE would be leading this investigation in the UK (and have powers of arrest), possibly resulting in more public confidence in the findings of any investigation they carry out.

RE: BP Explosion

The Chemical Safety Board www.csb.gov is investigating this incident, through tehe CSB does not have enforcement powers but generates regulations that are enforced by other goverment organizations such as OSHA www.osha.gov .

Vita sine litteris mors est.

RE: BP Explosion


Veritatis una vis, una facies est.
                                               Seneca

RE: BP Explosion

From the BP provisional 57 of the 70 trays within the column were flooded in the moment of the first explosion.

The splitter column have been out of service during one month and steamed out to remove hydrocarbons from February 26 to 28. The steam is usually prone to tray valves because after steaming the valves stuck with scale and after start up the vapor pressure of the ascendant gases is not enough to unplug the valves and the column get flooded. The flooding of the column was responsible for the high peak pressure of 63 psig when the maximum relief pressure was 42. In my opinion the high pressure in the splitter was responsible for the hydrocarbons release followed by explosions in downward equipment.
When tray columns are shut down for long time, just after start up is important to mechanically knock the valves or flush the column with water to dissolve the scale around them. The steam degasification should be done only just after start up.

Luis Marques

RE: BP Explosion

I have read the interim the report (and with me many others), it is witten such way, that people understanding the technology clearly could make out what has been going on.
  • workers not following procedures (managers, ceo's are also workers)
  • no supervision on critical moments
  • paperwork that is signed (Management of Change) after parking trailers
  • no crosscheck with outside instruments (column filling with no outlet and estimated time frame)
  • people taking 100% readings for granted, would rise serious questions about the credibility of maintenance
  • outdated technology (blowdown drum)
  • tie-in instead of phase out of connections to blowdown drum
are all signs of management deficiencies, the traditional part of the iceberg that is underwater.
By the way if non-technical journalists are interpreting the report as:

Quote (Yahoo):


BP PLC has backed off its earlier report that workers were primarily to blame for a March refinery explosion
you will get this mess, especially with a sue-happy public.

I saw in the report a summary of facts stated with evidence (no comments of spokesman this or union leader that).

RE: BP Explosion

Quote:

The steam degasification should be done only just after start up.

I have been in only two turnarounds but I question this statement.
  1. Shutdown
  2. Drain liquid in the tower
  3. Steam-out and drain condensate, this is done to get the column gas-free if you are going enter (confined space entry permit)
  4. Isolate!! Blank or Blinds list needed
  5. Inspection / Repairs
  6. Steam out again!!, you don't want oxygen in the system, hydrocarbons, oxygen and heat is an explosive mixture. That is why flare headers always have a slight positive pressure, if not  lpg or fuel gas is spiked in to keep the air (oxygen) out
  7. pressure up with lpg or gas
The last step is start-up (introducing feed)

RE: BP Explosion

Svanels

When a unit is planned for shut down, all degassing procedures should be followed. If columns are not supposed to be open for maintenance purposes, just after start up, is important to flush the column with water to dissolve the scale around valve trays to be sure that tray valves are free and able to tilt around tray holes to perform later its rectification job. If valve trays stay glued with scale, later on, the column will get flooded. The steam degasification to remove oxygen should be done only just after start up followed with nitrogen pressuring.
In   Texas City the splitter was shut down on February 21, steamed out 26 to 28, drained on March 14 followed by nitrogen pressuring and depressurized on March 21. Cold feed was brought on March22/23.

Luis Marques

RE: BP Explosion

Our definition of start-up is when we are introducing the feed (hydrocarbons), I think that why the confusion. But why between steaming out and draining the condensate there are almost two weeks? Is it not better to pressure the unit up with nitrogen earlier?

Of course we don't know the time frame/problems they were experiencing, but from the report it was stated that 2 start-up procedures were used.
Just curious.

RE: BP Explosion

unclesyd-

Good link. I received the slide show .pps a few days after the event. Pretty easy to note that it was not prepared on a BP/Amoco computer. Also when you take a closer look at the back of the firefighter turnout coats you'll note that not everybody belongs to the BP/Amoco refinery. It was a mutual aid situation. I'm wondering if anyone can substantiate the rumor that the person who shot the photos and/or released the slideshow is no longer employed...

jt

RE: BP Explosion

Just seen a report in one of the online magazines: "Pilot error"
BP is coming down hard on some operators and supervisors apparently.

JMW
www.ViscoAnalyser.com

RE: BP Explosion

All,

I have read the comments could you please answer some questions I had regarding the distillation column/ system.

I'm not familiary with the oil industry. So excuse me ignorance.

> Is Rafinate a trade name for mixture of heptane +.
> Whats the difference between light and heavy rafinate - BP are they both mixtures.
> It is common for oil industry columns not to have independent high level switches on distillation columns ? (I never design a column without one)
> on common vent stacks do you not normally have level alarms. (or even trips SIS2/3 .... /ESD 2,3)
> Why do they use fin fans not water cooled.

RE: BP Explosion

I am no chemical engineer, but IMO the heavy raffinate comes out the bottom, and the light comes out of the top. The light stuff is most likely a mixture of hydrocarbon gases.
It is also common to have high level switches that triggers alarms, emergency shutdowns etc.
Vent stacks like blowdown drums are dangerous, almost every where in the world they are substituted by flare systems.
Almost all hydrocarbon vapors are heavier then air, and will come down and acumulate in pits, sewers etc, if they are not flared (burned).
On the vent stacks there must be high level alarms, ESD's should be a difficult if different units are connected to the blowdown drum. Imagine 5 independent units connected, an upset in one of them could imply shutdown of all the others.

RE: BP Explosion

Quote:


on common vent stacks do you not normally have level alarms. (or even trips SIS2/3 .... /ESD 2,3)

In case of a trip / ESD in a unit, the quantity of gases to be vented increases, since their normal stream is disrupted. Stagnant gases combined with heat will build up pressures that must be released to the stack/flare.

RE: BP Explosion

Hello,

if you use two independent level transmitters which are mounted separately on the column you can go without switches etc.
They must be used as independent signals etc. So each of the two must be able to trigger actions (e.g. alarms, ESD's etc.).

Grtz
Ben

RE: BP Explosion

Actually lots of discussion is required to determine safety integrity levels for process units, systems and subsystems, etc.  The generalizations for one facility cannot hold for another.  A new facility might employ most of the following:
 transmitters instead of process switches,
 seperate systems for "basic regulatory process control" and safety shutdown,
 different technologies for the measurement devices for the diffent systems to avoid common mode failures,
 increasing levels of backup measurement where the safety integrety level for a process sub-system is elevated,
 ...

The unit at BP was not new.  Typically, a process hazard analysis is required every five years to re-visit safety levels, monitor management of change, ...  

The refinery codes and standards are typically not as stringent as required for offshore oil and gas production.  Thus, some things that are done within some facilities are not requirements.

John

RE: BP Explosion

One question to savnels (Petroleum).

You state that stagnet gasses will need to be released to the flare stack does this mean that the column runs very cold ? or is there a reaction.  Otherwise I dont understand why this is an issue.  My understanding of distillation columns.

If you stop feed/heat then as long as the MAWP of the column is higher than the saturated vapour pressure of the lightest component at the base P then you dont have an issue. Or is this a Low MAWP column because its cold.  

RE: BP Explosion

James we are dealing with hydrocarbons, which contains gases. Imagine a distilation train, consisting of heaters pumps, columns heat exchangers etc. Fired heaters are basically heat exchangers were crude passes through the tubes and an open flame on the "shell" side. We are talking about tube skin temperatures of near 600 C and product temperatures of 450 C or more.
If the heater feed pump trips, burners must trip also (interlock), the case is to get the feed running as quick as possible to prevent overheating of tubes and have a tube burst. As long as the product is running it is cooling also the pipes.

On the flare system various PSV's are coupled not only from the destilation tower. A trip results in temperature spikes in various points of the system, thus hydrocarbon gases are liberated which have to be removed by the flare system.
Whenever there is a trip the flames of the flare get higher, yellow with black smoke, indicating that an abnormal quantity of gases is flared.

Imagine you turn off the power switch of the whole plant (every operators nightmare). Theoretically you are not entering energy so things will cool off. The flare will be x-times higher then normal releasing "trapped energy"

The point is not only the distillation column, but the distillation train must be considered. There is no reaction involved in distillation (vacuum system) but when the temperatures run to high, coke will be formed in the pipe, which is a chemical reaction.

RE: BP Explosion

The full (Interim)report is available online at ww.bp.com/texascityincident.

HAZOP at www.curryhydrocarbons.ca

RE: BP Explosion

Does anyone know about the final report?

RE: BP Explosion

Don't know about BP's report plans, but the Chemical Safety Board is planning on holding a public meeting to discuss their preliminary report in September. I'd suspect that a final report would be issued a few months after that.

See second to last paragraph on page 4 of:
http://www.csb.gov/news_releases/docs/CSB%20BP%20Press%20Statement%206.28.05.pdf

Main incident page at:
http://www.csb.gov/index.cfm?folder=current_investigations&page=info&;INV_ID=52

jt

RE: BP Explosion

(OP)
According to the news BP had another excursion at the same site. The people near the site was just told they could come out of their house this morning.

I suppose there will be an addenda to the final report.  

RE: BP Explosion

Exploaion was in the resid hydrotreating unit.  Everything's under control now.

Larry

RE: BP Explosion

We have heard all the talk about what happened to cause the leak.  However, it is my understanding (correct me if I am wrong) that the area of interest here should be classified as a CLASS 1 atmosphere.  If this is the case the presence of combustable vapors isn't the only problem.

We have fuel and air...where is the spark.  From one of the medical respondants to the incident I have heard several injuriees stating that someone was running away yelling that his truck would not turn off (diesel).  Funny how the people who heard/saw this and took off are the ones that lived.

Anyone else have any tidbits as to the ignition source?

Incidentally I know of a few refineries that have started turning diesels away at the front gate if they are not equipped with an intake shutoff valve.

RE: BP Explosion

Subject: CSB Investigators Continue Assessment of July 28, 2005 explosion and fire at BP Amoco’s Texas City Refinery

The following message is from the United States Chemical Safety and Hazard Investigation Board, Washington D.C.

CSB Investigators Continue Assessment of July 28, 2005 explosion and fire at BP Amoco’s Texas City Refinery

Washington, DC, July 25, 2005 ­ Investigators from the U.S. Chemical Safety and Hazard Investigation Board today continued a preliminary investigation into the explosion and fire which occurred at the BP Amoco Texas City refinery last Thursday, July 28, 2005.
CSB Investigators Giby Joseph and Francisco Altamirano visited the site where the accident occurred for a second time.  They continued interviewing plant operators, and requested additional documentation and other information from the company regarding the chemical process underway at the time of the accident.  They arranged for eyewitnesses to be interviewed early in the week, and announced their intention to arrange testing protocols -- to examine a pipe that separated from a flange -- to determine what caused it to fail.
    
Mr. Joseph said the explosion occurred during what appeared to be a normal operation in the reactor section of the plant’s Resid Hydrotreater Unit # 1, or RHU, when an eight-inch pipe connected to a heat exchanger failed at the flange.  (Flanges are pipe fittings which are used to connect equipment such as pipes and valves.)  

“Recycled gas, primarily hydrogen, was suddenly released when the pipe broke away.  The hydrogen, under high pressure and temperature, was ignited, sending a large jet fire shooting an estimated 75 feet westward from the flange.  Damage was localized along that fire path,â€? Mr. Joseph said, addition that initial information indicates the hydrogen was pressurized at approximately 3,000 pounds per square inch at a temperature of over 500 degrees Fahrenheit.  Heat from the fire deformed piping and bent structural beams, he added.

Investigators said the reactor combines heavy crude oil with hydrogen as part of the conversion to lighter products.  There were no injuries from the incident.  Investigators were told that 13 workers were in the area, including several contractors.  BP has provided CSB investigators with handwritten eyewitness statements from employees, who will be interviewed this coming week by the CSB.

The incident occurred during routine operations, and not during maintenance or a startup.  CSB investigators say that witnesses report having received no warning indications before the pipe failure and explosion.

Investigators Joseph and Altamirano are part of the CSB team currently investigating the explosion and fire which occurred at BP on March 23, 2005, killing 15 workers and injuring more than 170 others.  After an initial assessment is made of the July 28 accident, the Board will determine the extent to which the latest accident will be further investigated, and whether it would form part of the ongoing investigation.

CSB Chairman Carolyn Merritt said, “Although this latest explosion and fire fortunately caused no injuries, such accidents are not an acceptable part of normal operations.  The accident occurred at an entirely different part of the Texas City facility, but we are interested in knowing whether the two accidents share any common root causes such as lack of an effective mechanical integrity program.  Such a program would make sure the equipment is safe and serviceable.â€?

Lead investigator Donald Holmstrom, in charge of the March 23 explosion investigation, will arrive on site Monday evening.

The CSB is an independent federal agency charged with investigating industrial chemical accidents.  The agency’s board members are appointed by the president and confirmed by the Senate.  CSB investigations look into all aspects of chemical accidents, including physical causes such as equipment failure as well as inadequacies in safety management systems.  Typically, the investigations involve extensive witness interviews, examination of physical evidence, and chemical and forensic testing.

The Board does not issue citations or fines but does make safety recommendations to plants, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA.  The Board designates formal responses to its recommendations as acceptable or unacceptable, open or closed.  Further information about the CSB is available from www.csb.gov.

For further information, contact Sandy Gilmour, cell 202.251.5496.

ATTN NEWS MEDIA: We do not expect to issue further information Sunday July 31, 2005.

This message was transmitted at 2:53 PM Eastern Time (U.S.A.) on July 30, 2005.

________________________________________________________

Visit us on the World Wide Web at http://www.csb.gov

Larry

RE: BP Explosion

Pzas - Hydrogen will ignite at the source of the leak due to the static charge formed during the release. This interpretation is supported by the characterization of the fire by the CSB investigators as a "jet fire". If ignition is delayed, such as by a remote source, the event is usually characterized as a vapour cloud explosion.

HAZOP at www.curryhydrocarbons.ca

RE: BP Explosion

We should start another BP RHU thread.  Pzas is talking about the March incident, which was a vapor cloud.  The July incident was a jet fire of hydrogen.

Larry

RE: BP Explosion

owg

I was referring to the first explosion, not the latest one.

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