martedì 3 novembre 2015

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1985 December - Naples - Fire and Explosion in a fuel storage area

Fire , Italy 0 Comments


This month CBS issued the final investigation report into the 2009 massive explosion at the Caribbean Petroleum. A very interesting video is available on the CSB’s website  as well as YouTube.
Today I do not want to talk about the Fire at Caribbean Petroleum Terminal Facility, but that accident reminds me of another event happened in Italy several years ago.



On December 21, 1985, at 5.13 a.m. a vapour cloud explosion occurred in a fuel storage area located in San Giovanni a Teduccio, near Naples, Italy.

Twenty-four of the 32 tanks at a large government owned marine petroleum products terminal were destroyed by a fire that began with a tank overfill.

A spill of gasoline occurred during a filling operation from the ship "Agip-Gela" berthed in the Naples harbour.
Gasoline overflowed through the roof of tank no. 17 for about 1.5 hours and the total amount of spilled fuel was estimated to be about 700 tons.

The resulting pool covered the bund area of the tank and the adjacent pumping area, which were connected through a drain duct. A large homogeneous vapour cloud formed due to the low wind speed, relatively high ambient temperature and a long delay prior to ignition.

According to some sources, the ignition source was in a pumping station and the resulting blast wave caused 5 casualties within the area.  The incident also caused 170 injuries and the evacuation of about 2,000 residents.


The strong explosion and the following fire, which lasted six days, destroyed all the buildings and the equipment within the area and 6 fixed roofs were found 50 m away from tanks.  A highway connection nearby was heavily damaged.

The main firefighting control center as well as electric and engine-driven fire pumps and foam lines were disabled. Efforts to extinguish the fire were handicapped by intense heat radiation and by debris from the explosion.

 About 800 firefighters with 166 pieces of mobile equipment were involved in emergency operation, consuming four-hundred and sixty tons of foam. This included airport crash trucks and even air tanker planes, which dropped foam on the fire.

The fire was extinguished on 27 December 1985, six days after it started.






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martedì 12 maggio 2015

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Hellfighters

Devil's Cigarette Lighter , Ekofisk Bravo 1 Comments

Hellfighters theatrical poster.jpg
Some week ago, I was intrigued by the title of a movie "Hellfighters", in which John Wayne portrayed Paul “Red” Adair.
Maybe you are wondering who this man is. Just to mention some of his feats I can remember the Piper Alpha and the Devil’s Cigarette Lighter.

Adair began fighting oil well fires after returning from serving in a bomb disposal unit during World War II. He started his career working for Myron Kinley, the "original" blowout/oil firefighting pioneer. In the 1959 he founded Red Adair Co. Inc. and over the course of his career battled more than 2000 onshore and offshore oil wells, natural gas wells and similar spectacular fires.

His usual method was to blow out a fire by detonating explosives nearby. This meant that surrounding materials needed to have cooled sufficiently for the escaping oil and gas not to reignite; thus, the wellhead had to be cooled with large amounts of water first.


Devil's Cigarette Lighter

Adair gained his international reputation in 1962, when he tackled a fire at the Gassi Touil gas field in the Algerian Sahara nicknamed the Devil's Cigarette Lighter.
Ignited when a pipe ruptured on November 6, 1961, the Phillips Petroleum Company-owned well produced more than 6,000 cubic feet (170 m3) of natural gas per second, whose flame rose between 140 m and 240 m.
To get a picture of how big the blaze was astronaut John Glenn said he could see the fire raging when he was circling the Earth in an aircraft in space.
The blowout and fire were estimated to have consumed enough gas to supply Paris for three months. After burning almost six months, the fire was extinguished by Adair, who used 500 tons of explosives to deprive the flame of oxygen and capped the well.


Ekofisk Bravo platform

In 1977, he and his crew contributed to the capping of the biggest oil well blowout ever to have occurred in the North Sea (and at the time the largest offshore blowout worldwide, in terms of volume of crude oil spilled), at the Ekofisk Bravo platform, located in the Norwegian sector and operated by Phillips Petroleum Company (now ConocoPhillips).


PIPER ALPHA

In 1988, Adair was again in the North Sea where he helped to put out the UK sector Piper Alpha oil platform fire.  
The platform's legs were anchored 400ft beneath the North Sea, and more than 30 pipes were sucking up 30,000 barrels of crude oil as fire continued to engulf the platform.

Adair directed operations from aboard Tharos, the rescue and support ship which he had himself designed, and which pumped water on to the platform.

Piper Alpha was not the worst oil rig fire Red Adair had to deal with, but it was a job he hated because for the first time in his life he was not in there with his men fighting the blaze.
He brought the fires under control in three weeks, first pumping cement into the wells and then capping them.


Adair later recalled:
"We found that we were fighting the fires and the elements of the North Sea. We had this weird weather, 80-mile-an-hour winds, 70ft seas which they hadn't seen in 50 years."


KUWAIT

 In the final day of the Gulf War 1991, at age 75, Adair took part in extinguishing the oil well fires in Kuwait set by retreating Iraqi troops.
Although it was thought that controlling these fires, fuelled by the country’s rich oil reserves, would take years to accomplish, Adair’s team capped 117 wells and aided others teams in completing the job in eight months.

Adair died in 2004, aged 89 and I like to remember him with the following quote:











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venerdì 6 febbraio 2015

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Hazardous area classification: when a flammable gas is not polite (and exceeds the Classified area)

Hazardous area , USA 0 Comments

In the following video, a hydrocarbon gas release occurred in a Refinery on July 2009 in Texas:


(in case of problem to see the video click here)

In my experience, I have often discussed with people having a strange idea: for them in order to avoid a gas explosion in their plant the Hazardous area classification is enough (and you can understand that they apply the classification just because it is a law requirement or it is indicated in their company standard).

So sometime you can see in some plants where in hazardous area there are equipment suitable and certified for Hazardous (that’s good!) but just at half a meter outside the classified area a standard equipment (not suitable for hazardous area – and that’s not good!!).
They trust in the Hazardous area classification and in particular that the flammable gas cannot betray their trust: but sometime the flammable gases are not polite.

What they don’t know is that the purpose of hazardous area classification is to minimize the probability of ignition of small leaks: It is not concerned with massive releases, which are generally defined as “catastrophic release” or "Major Accident".

For instance in the "IEC 60079 Part 10-1: Classification of areas – Explosive gas atmospheres"  it is indicated:
“IEC 60079 …is intended to be applied where there may be an ignition hazard due to the presence of flammable gas or vapour, mixed with air under normal atmospheric conditions, but it does not apply to …catastrophic failures which are beyond the concept of abnormality dealt with in this standard”.

And they specify in a note what they mean:  “Catastrophic failure in this context is applied, for example, to the rupture of a process vessel or pipeline and events that are not predictable”.

Another important standard for Hazardous area classification is the API RP 505, where we can find that:
“the following items are beyond the scope of this document: …Catastrophes such as well blowouts or process vessel ruptures. Such extreme events are not predictable and require emergency measures at the time of occurrence.”

What could be the right solution for these events?

The best solution generally is not a single one but the right combination different measures, especially for some kind of industries with an high risk of Major Hazard Events.

Generally I have seen a combination of the following actions:
• Equipment suitable for Zone 2 Hazardous area in process areas also outside the classified area and especially for emergency devices (emergency lighting, navigation aids, etc.);
• installation of gas detectors with a logic that in case of confirmed gas can activate the shutdown of all potential sources of hazard and ignition and in particular the de-enegization of all the equipment not-suitable for hazardous area.

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lunedì 19 gennaio 2015

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Explosion and sinking of the Deepwater Horizon Mobile Offshore Drilling Unit

Blowout , USA 0 Comments


The Blowout occurred on the Deep Water Horizon is one of the most famous disasters of recent times. Defined as an “uncontrolled release of fluid from a well”, Blowout is widely perceived as one of the main accident hazard offshore (perhaps because major blowouts tend to persist for long enough to be widely reported).

For me one of the most interesting reports produced is that of CSB from which I got a lot of information in order to understand what really happened (for more details see their website).

I think I should also highlight the beautiful section on website of the NewYork Times, with very clear illustrations and interviews with survivors).


1 - Introduction

1.1 - The Equipment

The Deep-water Horizon (DWH) was a semi-submersible, dynamically positioned, mobile offshore drilling unit (MODU) that could operate in waters up to 8,000 feet deep (91,440 mt) and drill down to a maximum depth of 30,000 feet (2,400 mt). The rig was built in South Korea by Hyundai Heavy Industries. The rig was owned by Transocean, and was under lease to BP from March 2008 to September 2013.

The DWH was a dynamically positioned rig that used global satellite technology and thrusters to maintain position over the well rather than cables and anchors to hold it in place.

At the time of the accident, the rig was drilling an exploratory well at a water depth of approximately 5,000 feet (1,524 mt) in the Macondo Prospect. The well is located in Mississippi Canyon Block 252 in the Gulf of Mexico.

BP planned to drill two exploration wells—Macondo being the first—and follow with a production facility if the oil and gas-bearing region revealed commercial potential.
BP designed Macondo for use as a producing well if successful, but the well was, in fact, exploratory because of the uncertainty about both the type and quantity of the oil and gas (hydrocarbons) present at the site and the effort necessary to actually extract the oil and gas. If the well proved commercially viable, data concerning the well’s geology and hydrocarbon properties would be collected and used to create a production plan; alternatively, if the well was not viable, the data would be gathered to determine why the commercial predictions failed.

Ultimately, as BP hoped, the Macondo well was appropriate for conversion to a producing well.

1.2 - Planning the Well

The goal of drilling a deepwater well is to create a pathway between oil and gas reservoirs trapped beneath the seafloor and the surface. To reach the reservoirs, a hole (the wellbore) is drilled through various layers (formations) of rocks and/or unconsolidated sediments such as sand, shale, gravel or silt. The formations, such as the target reservoir, are porous and permeable, and they contain water, oil, and/or gas which are under pressure.

An unplanned flow of these fluids into the wellbore is called a “kick”, which, if not managed, can progress to a “blowout,” the uncontrolled release of oil and gas (hydrocarbons) from the well. This is most dangerous for people and property when the hydrocarbons release onto the drilling facility, where ignition sources are present.

Thus, the flammable and potential explosive nature of oil and gas contained in the reservoir(s) of a potential well is one of the most significant major hazards that must be managed throughout the lifecycle of a drilling and production operation, beginning with the planning stages of the well. Part of the planning process is a well-specific hazard analysis of the operation to determine the appropriate safeguards for mitigating the hazard and control of the risks.


2 - The Accident

2.1 - Events before the incident

At the time of the accident, the Deepwater Horizon (DWH) crew had finished drilling and was completing temporary abandonment of the well so that a production facility could return later to extract oil and gas from the well.

At the time of the blowout, 126 people employed by 13 different companies were onboard the DWH.

BP’s temporary abandonment plan called for removal of most of drilling fluid column in the well before installation of a surface cement plug. Earlier, a critical cement barrier intended to keep the hydrocarbons below the seafloor had not been effectively installed at the bottom of the well, and the cement integrity was not conducted in a way that provided a clear “pass” or “fail” result to the workers. Both BP and Transocean personnel on the DWH rig misinterpreted the test results concerning the cement integrity, leading them to erroneously believe that the hydrocarbon bearing zone at the bottom of the well had been sealed when in fact it was not.

2.2 - Incident

When the drilling fluid column was removed, pressure gradually reduced above the hydrocarbon reservoir at the bottom of the well. Eventually, this action allowed hydrocarbons to flow past the failed cement barrier and up toward the DWH. Meanwhile, because of a failure to recognize the increase in fluids from the well, the crew continued to remove more of the drilling fluid column, causing both the hydrocarbon influx rate into the well and movement of hydrocarbons toward the rig to increase. The hydrocarbons continued to flow from the reservoir for almost an hour without human intervention or the activation of automated controls.


2.3 - And the gas detections??

“A worker on a crane sees gas spreading across the rig.  A mixture, including mud and gas, initially gushes out of the well and cascades off the drilling floor. It then shoots up inside the derrick.”

The force of the hydrocarbons accelerating up the mile-long drilling riser resulted in well fluids gushing onto the drilling rig floor—a blowout.

Gas sensors go off but the bridge does not activate emergency systems that might have prevented gas from spreading or igniting. The crew members on the bridge also do not immediately sound a general alarm to start evacuation. While they inform the engine control room of a well control situation, they tell them nothing about the erupting mud or gas alarms

At this point, the crew took action to activate the blowout preventer (BOP). This safety critical element, located at the sea floor, temporarily sealed the well but could not stop the hydrocarbons that had already traveled above the BOP from releasing onto the rig.

Once oil and gas had risen above the BOP, the only action the crew could take was to divert it to a safer location than onto the rig floor. However, the flow from the diverter had been preset to route well fluids to the mud-gas separator rather than over the side of the Deepwater Horizon. The mud-gas separator was rapidly overwhelmed, as it was not designed to safely handle a flow of the magnitude of the Macondo blowout. As a result, drilling mud and hydrocarbons rained down onto the rig floor.
A chief mechanic and three others in the engine control room are aware of gas on the rig but do not activate an emergency shutdown. They later say that the protocol is to wait for instructions from the bridge.

The hydrocarbons found an ignition source, and explosions and fire ensued.

 “Engines 3 and 6 are believed to be at the center of two major explosions.
The four men are caught  between the blasts, but all survive.”


Both manual and automated emergency systems within the blowout preventer were activated in an attempt to shear the drillpipe and seal the well. However, pressures in the well had caused the drillpipe to buckle, which inhibited the BOP from sealing the well.

The explosion and fire resulted in 11 crew members suffering fatal injuries and 17 others being critically injured.

The Deepwater Horizon rig sank on April 22, 2010, about 36 hours after the initial explosions. Approximately 5 million barrels of oil spilled into the Gulf of Mexico.
Ultimately, in the hours leading up to the incident, no effective barriers were in place to prevent or mitigate a blowout. The physical barriers intended to prevent such a disaster were not properly designed for the well conditions, constructed, tested, or maintained, or they had been removed. The management systems intended to ensure the required functionality, availability, and reliability of these barriers were inadequate.

An examination of the treatment of safety critical equipment and tasks at Macondo, such as the BOP and cement barrier testing, reveals opportunities for further improvements in effective barrier safety management. Furthermore, a comparison of the US regulatory requirements for these safety critical elements to other international offshore regimes illustrates gaps in the US model and offers support for further post-Macondo changes to the US offshore safety regulations.


From shortly before the explosions until May 20, 2010, when all ROV intervention ceased, several efforts were made to seal the well. The well was permanently plugged with cement and “killed” on September 19, 2010.






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