Explosion Gsc

WELCOME

ONE DAY SEMINAR ON

FIRE RISK & EXPLOSION IN INDUSTRIES

DECEMBER 06 , 2003

AT HOTEL EXPRESS , VADODARA

WELCOME

CASE STUDIES ON

FIRE RISK & EXPLOSION IN INDUSTRIES

BY

Shri Sanjay V Shinde

DY. MANAGER ( FIRE & SAFETY)

CASE STUDIES ON CASE STUDIES ON FIRE RISK & EXPLOSION IN INDUSTRIESFIRE RISK & EXPLOSION IN INDUSTRIES

S V SHINDE

DY. MANAGER ( FIRE & SAFETY )

INDIAN OIL CORPORATION LTD.

GUJARAT REFINERY,

INDIA

What is gas an explosion :-

A PROCESS WHERE COMBUSTION OF A PRE-MIXED GAS CLOUD CAUSES A RAPID INCREASE IN PRESSURE.

THE PRESSURE INCREASE OR “ OVERPRESSURE”DEPENDS UPON THE DEGREE OF CONFINEMENT

Explosion :-

Explosion can occur either in the form of a deflagration or a detonation depending upon the burning velocity during an explosion.

Deflagration occurs when the burning velocity of the flame speed is relatively slow, of the order of 1 m/ sec and peak pressure developed reaches to 70-80 kpa

In detonation, the flame speed is extremely high. The flame front travels as a shock wave ,with a typical velocity of 2000-3000 m / sec. Detonation generates peak pressure of magnitude 200 kpa and is more destructive than a deflagration

Types of gas explosion :-

Confined explosion :- ( vessel , building , engine room etc)

Mechanical ventilation system can help in preventing the building up of explosive gas cloud, but they can also result in ingestion of gas from outside.


Partly Confined explosion :- ( offshore module )

The explosion overpressure is a function of size and location of openings and congestion within the compartment


Un-Confined explosion :- ( refinery , petrochemical units )

Un confined explosion can still develop significant overpressure,particularly if the flammable cloud is large, the gas is volatile and there is a significant congestion.


BLEVE

( Boiling Liquid Expanding Vapor Explosion )

An explosion due to rupture of a vessel containing a high vapor pressure liquid.

A BLEVE can result in very large fire ball and rocketing projectiles.

Potential sources and causes of Release :

.

sourcessources causescauses

Instrument connectionsInstrument connections Mal-operationMal-operation

Pipe workPipe work failure to follow proceduresfailure to follow procedures

FlangesFlanges Poor safety culturePoor safety culture

ValvesValves Inadequate precautionsInadequate precautions

Heat exchangersHeat exchangers corrosioncorrosion

CompressorsCompressors ErosionErosion

PumpsPumps Fatigue / vibrationFatigue / vibration

VesselsVessels impact / gasket, seal impact / gasket, seal failure /over pressurisation failure /over pressurisation

Sources of ignition

• Electrical equipment

• Static electricity

• Hot surfaces

• Engines

• Hot work (welding , grinding,flame cutting)

• Naked flames

• smokingContinue…

Sources of ignition

• Fired boilers

• Impact

• Friction

• Auto-ignition ( Hydrogen , Acetylene )

• Introduced sources

• Intermittent sources

Worst explosions in the world

Flixborough 1974

The plant was totally destroyed and over 100 houses in the area were damaged.28 nos of people were killed

A temp pipe failed resulting in release of an about 50 tons of cyclohexane in atmosphere, this caused a very large flammable cloud of heavy vapor to form ,which ignited after 01 minute resulting in a violent explosion equivalent to about 16 tons TNT ( Tri-nitro-toulene)


Mexico city 1984

A major fire and series of an explosions occurred at the PEMEX LPG plant destroying the terminal and killing approx 500 people.

A large release of LPG occurred from a ruptured pipe. After approx 10 minutes,the flammable cloud reached a flare and ignited. This was followed by a large fire and series of explosion as many LPG vessels suffered BLEVE


PIPER ALPHA 1988

An explosion caused fires which subsequent resulted in rupture of the riser and total loss of platform

167 nos of people were killed


PASADENA TEXAS 1989

Incorrect connection of a valve during the maintenance operation resulted in a release of ethylene,isobutane , hexene and hydrogen.

About 40 tons of gas was released. The flammable gas cloud ignited after about 02 minutes resulting in amassive explosion followed by a fire and further explosions. The plant was destroyed and there were 23 nos of fatalities.


Conoco oil refinery, lincolnshire, 2001

An elbow on a de-ethaniser column failed due to corrosion resulting in the release of approximately 06 tons of ethane / propane within about 07 seconds.

The vapor cloud formed was ignited by a furnace 80 meters away. The explosion caused the rupture of other lines resulting the release of a further 08 tons of LPG and large fire ball. Two persons were injured


KNPC ,OIL REFINERY

An explosion caused by a gas leak at Kuwait's Mina Al-Ahmadi refinery on June 25, 2000 killed four people and injured 49 others, according to the Kuwaiti News Agency. The refinery was to be closed for 7-10 days for an investigation and damage assessment, says KNPC. Some units at the refinery would be out of operation for months and others for several weeks. KNPC says two 18,000 b/d gasoline units were severely damaged by the explosion and fire. A 122,000 b/d crude unit suffered major damage, while a 120,000 b/d crude unit suffered moderate damage. Poltical fallout was swift, with the Kuwait Oil Minister offering for resignation

TOSCO AVON REFINERY FIRE

Case study : 01

INCIDENT :

On febrary 23, 1999, four workrs were killed in a fiery accident at Tosco corporation’s Avon refinery in Martinez, California

The men were in the process of replacing ,corroded pipes at one of the refinery’s oil fractionators, a 150 feet distillation tower designed to heat and separate components of crude oil


INCIDENT :

Because the project was classified as a low risk routine maintenance, no special precautions were in lace. The fractionator continued to operate, with large volumes of flammable vapor and liquid flowing inside the tower and it’s attached piping

The surface temp of the equipment was over 500 deg. fahrenheit


What is fractionator ?

Crude oil fractionation is the first step in oil refining process. A fractionator is a vesselthat separates heated crude oil into components such as natural gasoline,naphtha,kerosene and diesel.

Inside the vessel, trays are used to collect the different fractions as liquids.

Pipes connected to each tray withdraws the liquids to storage or other processes. Processing is continuous


Description in detail :-

Earlier that morning ,under the direction of maintenance Supervisor, workers had removed a section of corroded naphtha piping 112 feet up the tower,near where the piping joined the fractionator.But things had not been going as planned. When a second cut was made 26 feet below the first, naphtha-a volatile hydrocarbon began to ooze out and workers had to immediately reseal the pipe.

After lunch,the workers climbed 40 to 100 feet up scaffolding alongside the tower. They tried to drain the piping system of naphtha by opening a pipe flange 36 ft.


Description in detail :-

Up and directing the leaking fuel into a vacuum truck using makeshift plastic sheeting and a bucket.

The operation proceeded without apparent problem for 30 minutes, when suddenly a large volume of naphtha, propelled by vapor pressure from the operating fractionator,shot out of the open pipe overhead,spraying the workers.

For the five men high on the scaffold, there were few avenues of escape as the hot surface of the fractionator ignited the naphtha, engulfing them in flames.


What went wrong ?

A) RECURING NAPHTHA LEAK

On Feb 10, operators had observed a naphtha leak coming of the fractionator, which they treated as an emergency at the time. They located pinhole leak in the naphtha piping 112 feet up and closed aseries of valves in an effort to eliminate it.But the leaks kept reccuring.In succeeding days, one attempt after another failed to completely staunch the flow of naphtha. Shut-off valves malfunctioned repeatedly and drain valves were found to be clogged beyond use or repair.


What went wrong ?

A) RECURING NAPHTHA LEAK

Ultrasound and x-ray tests were ordered, and these revealed that both the piping and the valves were severely corroded and needed to be replaced. Although the unit operator argued for shutting down the process before attempting to replace the deteriorated piping,a maintenance supervisor decided to do the job while he hot fractionator continued to run. This fateful decision did not receive any scrutiny from the management.


What went wrong ?

B) PROCESS SHOULD HAVE BEEN SHUT DOWN

Good operating practice calls for draining hazardous materials from lines and equipment and verifying that the equipment has been isolated before opening for maintenance. But that could not be done at Tasco so long as the fractionator was operating. The repeated recurrence of naphtha leaks was a strong indicator that shut-off valves were corroded and were not functioning properly. As long as the fractionator was running , naphtha continued to leak into the piping , and vapor from the fractionator pressurized the escaping fuel.

.


What went wrong ?

B) PROCESS SHOULD HAVE BEEN SHUT DOWN

In the 13 days that elapsed between the first occurrence of the leak and the fatal accident ,Tosco personnel missed numerous opportunities to reassess the hazards of the pipe replacement work and take measures to ensure the work would be performed safely. In his case, such safety measures would have been included shutting down the fractionator as the only way to eliminate both the source of the naphtha and the potential source of it’s ignition.

.


What went wrong ?

C) CORROSION AND MANAGEMENT OF CHANGE PROGRAM INADEQUATE

The naphtha piping and valves had been run to the point of breakdown due to corrosion,leading to a potentially hazardous situation. The valves and piping had corroded at an excessive rate because an upstream vessel known as the crude oil desalter-which removes salt, water and solids from the oil feed – was being operated beyond it’s design limits. Tosco had routinely processed excessive volumes of crude oil with high water content, overtaxing the desalter.

As a result, water and corrosive materials like ammonium chloride were carried over into the fractionator,where they began to deteriorate the piping and valves.


What went wrong ?

C) CORROSION AND MANAGEMENT OF CHANGE PROGRAM INADEQUATE

Tosco should have evaluated operational changes that could worsen the corrosion of piping and valves.

These changes included feeding different material into the process,increasing the amounts being processed and making long term adjustments to valve positions. Such was not applied to these process modifications. This omission contributed to the final breakdown and the fire..


What went wrong ?

D) DEVIATION FROM SAFE PRACTICES WERE NOT

CORRECTED

The incident highlighted several ineffective safety practices and procedures at the AVON refinery. This tragedy could have been prevented had better procedures been in place for opening process equipment, controlling sources of hazardous energy, managing process changes and isolating piping prior to maintenance

But problems existed in these areas before the FEB 1999 fire occurred. Had Tosco management conducted an safety audit of these programs, problems could have been corrected prior to the accident.

However ,no relevant documented safety audits were performed during the three years leading to the fire


Key recommendations :-

•TO IMPLEMENT A PROGRAM TO ENSURE THAT HAZARDOUS

NON- ROUTINE MAINTENANCE IS CONDUCTED SAFELY

•REFINERY SHOULD REQUIRE A WRITTEN HAZARD

EVAULATION BY A MULTIDISCIPLINARY TAEM BEFORE ANY

HAZARDOUS JOB IS STARTED.

•REFINERY SHOULD REQUIRE HIGHER LEVELS OF APPROVALS

FOR HIGHER HAZARD JOBS, DEVELOP A WRITTEN PROTOCOL

FOR MAKING SHUTDOWN DECISIONS, AND MAKE SURE THAT

MANAGERS AND SAFETY OFFICIALS PROVIDE AEQUATE

OVERSIGHT FOR HAZARDOUS WORK


Key recommendations :-

•THE REFINRY SHOULD IMPROVE IT’S MANAGEMENT OF

CHANGE AND CORROSION CONTROL PROGRAMS TO

PREVENT SITUATIONS WHERE SAFETY IS COMPROMISED.

• AUDIT FINDINGS AND RECOMMENDATIONS SHOULD BE

SHARED WITH THE WORKFORCE AND TRACKED TO

COMPLETION.

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