September 29, 2018
September 26, 2018
September 22, 2018
September 18, 2018
Leak due to vibration
A specialized rubber manufacturing plant experienced leakage of a hexane solution from a pump discharge flange during use. The hexane vapor was ignited by a st atic electricity spark and a fire occurred. Apparently, the flange was loosened by vibrations from the pump.Routine operations were being carried out on site at the time of the accident.
The operation involved the transfer of a hexane solution from an un-reacted raw material recovery tank to the washing process through the outlet of the first flange of the pump. The hexane solution
leaked, ignited, and burned. The financial costs of recovery and lost production were significant.
Causes
The cause of the accident was a loose flange that resulted in leakage of a flammable substance. During the operation, a previously undetected cavitation in the pump produced significant vibration
which loosened the flange. As a cause of the ignition it was considered that the hexane was charged when it spouted from the flange, and static electricity was discharged; then hexane vapor ignited
and a fire occurred.
It was considered that the vibration might have been intensified by the passage of an insoluble polymer lump through the pump, a malformation in the substance generated on the piping wall. In addition, a reducer connected a 3-inch (~75mm) flange of the discharge pump to 6-inch (~150mm) piping. The looseness of this flange might have been accelerated when the force
of vibration was added on the piping.
Lessons learned
Vibrating equipment can increase potential for stress fractures and gaps from loosely fitting interfaces, all of which can be sources of leaks that, if undetected, may result in an accident. It is necessary to pay sufficient attention to vibrating equipment, especially pumps that may be found in many processes throughout the site. Control measures to mitigate potential risks could include regularly scheduled inspections in line with existing technical standards or in-house experience, particular attention to small-bore piping (vulnerable to fatigue), installation of a vibration monitor to detect and locate abnormal vibration patterns, as well as other measures available in guidance
on vibrations from numerous sources.
Source: European Commission
The operation involved the transfer of a hexane solution from an un-reacted raw material recovery tank to the washing process through the outlet of the first flange of the pump. The hexane solution
leaked, ignited, and burned. The financial costs of recovery and lost production were significant.
Causes
The cause of the accident was a loose flange that resulted in leakage of a flammable substance. During the operation, a previously undetected cavitation in the pump produced significant vibration
which loosened the flange. As a cause of the ignition it was considered that the hexane was charged when it spouted from the flange, and static electricity was discharged; then hexane vapor ignited
and a fire occurred.
It was considered that the vibration might have been intensified by the passage of an insoluble polymer lump through the pump, a malformation in the substance generated on the piping wall. In addition, a reducer connected a 3-inch (~75mm) flange of the discharge pump to 6-inch (~150mm) piping. The looseness of this flange might have been accelerated when the force
of vibration was added on the piping.
Lessons learned
Vibrating equipment can increase potential for stress fractures and gaps from loosely fitting interfaces, all of which can be sources of leaks that, if undetected, may result in an accident. It is necessary to pay sufficient attention to vibrating equipment, especially pumps that may be found in many processes throughout the site. Control measures to mitigate potential risks could include regularly scheduled inspections in line with existing technical standards or in-house experience, particular attention to small-bore piping (vulnerable to fatigue), installation of a vibration monitor to detect and locate abnormal vibration patterns, as well as other measures available in guidance
on vibrations from numerous sources.
Source: European Commission
September 14, 2018
Common Causes of Gasket Failure
Common Causes of Gasket Failure: During the course of our 50 years in business, Associated Gaskets has seen many different types of gasket failures. Sometimes these were seen late at night when we were called out to help with an emergency, other times it was when one of our own gaskets was returned after failing …
September 10, 2018
September 6, 2018
Global warming and its effect on process incidents
As the effects of global warming are being felt, chemical industries must acknowledge the fact for planning for natural disasters. The "Fire from ice" video about the Valero refinery incident and The Arkema incident due to Hurricane Harvey are two examples related to climate. Cyclone maximum wind speeds are increasing and past weather data may not be a reliable predictor about the future. What are you doing about it?
September 3, 2018
Gasket failure incident
On 5th January 2008 a production operator discovered a fair sized phenol leak in the phenol pump house next to the phenol storage tank. One of the gaskets on the flange connection on the outlet pipe of the tank had failed. The head of the operations department tried to stop the leak by tying a rubber belt around the flange. In the meantime, an operator sprayed water on the flange to avoid contact with phenol as much as possible. The phenol that had leaked was collected in a catchment pit of 20 m3 underneath the pump house. This catchment pit had a high level alarm, but it was not functioning at the time of the leak. The company was not aware of the malfunction because the alarm was not subject to periodic inspection.
An attempt was made to close the only manual valve on the pipe,located between the inner and the outer tank shells, but the valve spindle broke off during this manipulation, so the line could not be
shut off. After the temporary repair of the flange connection, three leaks continued to release phenol, which were also collected in the catchment tank. It was not allowed for the employees to enter the
pump house while the phenol was leaking. To clean up the catchment pit, the company provided a waste tank big enough to contain all the leaked phenol. When starting to pump the phenol from the catchment tank to the waste tank, it was discovered that the catchment pit had overflowed. Part of the
phenol/water mixture had passed over the rim of the open pit into the municipal sewer system. At the time, it was not yet known how much phenol had leaked to the sewer system.
On 7th January 2008 it was decided to start up the phenol-based batch production to consume all phenol in the storage tank since the phenol tank had to be taken out of service in order to replace
the gasket on the flange. On January 8th, after a few batch productions, it was found out that the level indicator in the phenol storage tank had become stuck since the last control of the level on 4th January (comparison of manual level measurement with level indicator). Only at that moment did the company realize that 25t of phenol had leaked out of the tank. The catchment pit probably
collected most of the release, but more than 5t of the phenol spilled into the municipal sewer. No consequences were reported as a result of the release into the municipal sewer. A specialized
company was hired to repair the remaining phenol leak.
Causes
In this case, a variety of causes contributed to the accident. The direct cause was the degradation of gasket that caused the leak. After the flanges and valves were replaced following the accident, it
was discovered that the valve broke down because the gasket next to it had been reacting with phenol over the course of many years, leading to a solid deformation that prevented the valve from moving,
hence, the valve could not be closed. The spindle of the manual valve at the tank broke off as a result of the deformation of the adjacent gaskets.
Source: European commission
An attempt was made to close the only manual valve on the pipe,located between the inner and the outer tank shells, but the valve spindle broke off during this manipulation, so the line could not be
shut off. After the temporary repair of the flange connection, three leaks continued to release phenol, which were also collected in the catchment tank. It was not allowed for the employees to enter the
pump house while the phenol was leaking. To clean up the catchment pit, the company provided a waste tank big enough to contain all the leaked phenol. When starting to pump the phenol from the catchment tank to the waste tank, it was discovered that the catchment pit had overflowed. Part of the
phenol/water mixture had passed over the rim of the open pit into the municipal sewer system. At the time, it was not yet known how much phenol had leaked to the sewer system.
On 7th January 2008 it was decided to start up the phenol-based batch production to consume all phenol in the storage tank since the phenol tank had to be taken out of service in order to replace
the gasket on the flange. On January 8th, after a few batch productions, it was found out that the level indicator in the phenol storage tank had become stuck since the last control of the level on 4th January (comparison of manual level measurement with level indicator). Only at that moment did the company realize that 25t of phenol had leaked out of the tank. The catchment pit probably
collected most of the release, but more than 5t of the phenol spilled into the municipal sewer. No consequences were reported as a result of the release into the municipal sewer. A specialized
company was hired to repair the remaining phenol leak.
Causes
In this case, a variety of causes contributed to the accident. The direct cause was the degradation of gasket that caused the leak. After the flanges and valves were replaced following the accident, it
was discovered that the valve broke down because the gasket next to it had been reacting with phenol over the course of many years, leading to a solid deformation that prevented the valve from moving,
hence, the valve could not be closed. The spindle of the manual valve at the tank broke off as a result of the deformation of the adjacent gaskets.
Source: European commission
August 31, 2018
August 28, 2018
August 27, 2018
Rupture of sulphuric acid tank
On 4th February 2005 a storage tank containing 16,300 t of
96 % sulphuric acid ruptured. The entire contents of the tank were spilled out
into the bund and then overflowed out into the nearby dock. The environmental
consequences of the accident were quite significant,the sulphuric acid emission
had a serious effect on local flora in the inner and deepest parts of the
harbor and harbor entrance area. When the sulphuric acid came into contact with
the salt water an exothermic reaction occurred, producing a vapour cloud
consisting of hydrogen chloride that drifted northwards along the coastline in the
direction of the wind. Fortunately, the wind was blowing towards the sea and
away from populated land areas and the cloud diluted very quickly. After the
spill approximately 2,000 t of contaminated sulphuric acid remained in the
bund. The acid also soaked into about 100,000 square metres of the ground
surrounding the spill.
Causes
The cause of this incident was a leak in an underground
coolant supply pipe of reinforced concrete installed over forty years before that
resulted in a weakening of the ground under the tank farm. Apparently, water
forced its way out of the pipe, eroding the ground near and around the
sulphuric acid tank. This erosion damaged the ground under the tank which
ultimately failed due to the lack of support of the tank floor. A study of the
appearance of the involved part of the coolant supply pipe suggests that the
corrosion was a result of an acidic attack on the concrete.
Important findings
• The damage indicates that the acid exposure occurred over
a long period of time. However, it was not possible to determine the exact duration
of the exposure.
• The pipe had been in use over many years and the operator
had mno suspicion that the pipe was suffering severe degradation. The inspection
of the failed pipe after the incident detected little or no internal corrosion,
but heavy external corrosion to the concrete. In certain places the concrete
had corroded so severely that the reinforcing steel was exposed.
• According to the German standard, DIN 4030 (equivalent to
the European standard, EN 260) a strong attack on concrete occurs if the pH
level in surrounding water is < 5.5 and a very strong attack can occur if
the pH level is < 4.5. Fifteen years before the accident a ground pollution
study was carried out in the area, during which one of the sample taking points
was close to the failed coolant supply pipe. At this point the pH level was
measured at 4 in the shallow groundwater. With this knowledge the company drew
the conclusion that this pH level entailed risks for strong acidic attackson
the concrete.
Lessons learned
• The uneven corrosion on the outside of the pipe can
possibly be explained by the fact that it lay partly in groundwater flow. In
this environment, the acid can pass through the barrier more easily, and the
reaction products (gypsum) formed can be more easily dissolved. As such, the
concrete barrier was not as effective as on the part of the pipe that remained
in drier surroundings. Therefore, concrete piping exposed to ground water
should be should be subject to protective measures, monitoring and inspection
to take into consideration the increased risk from groundwater exposure.
• Similarly, underground piping that entail risks to
foundations should be inspected and measured..
• There are a number of strategies that can be applied to
piping where there is accelerated potential for degradation or where there are
high consequences should significant degradation occur.
Pipes may, for example, be tested for stability (remains in
place) and hydraulically checked on a regular basis. Alternatively,
consideration should be given to positioning the pipe above ground. The pipe
could also be placed in casings, especially where a leak may cause damage to
the surroundings or where pressure and ground deformation may cause damage to
the pipe.
Source: European commission
August 24, 2018
Confined space fatality
Confined space fatality – Sharp LadyThe
Isle of Man Ship Registry has published Casualty Investigation Report
No. CA118 on a confined space entry fatality that occurred on a crude
tanker. The incident occurred after discharging crude oil. Equipment was
lost at the bottom of a tank. It was decided that once the discharge
was finished and crude oil washing completed, the equipment should be
retrieved before loading the next cargo into this tank, to avoid any
potential damage to the ship’s equipment.
The Chief Officer and Cadet entered the cargo tank after an enclosed space work permit and risk assessment had been completed. When the Chief Officer and Cadet reached the bottom of the cargo tank they felt debilitating effects of hydrocarbon vapour present at the lower level of the cargo tank. Both the Chief Officer and Cadet attempted to activate their Emergency Escape Breathing Devices (EEBD) and exit the cargo tank.
The Master observed the Cadet in difficulty and quickly entered the tank, ignoring the advice of a fellow crew member. The Chief Officer successfully exited the cargo tank but the Cadet had collapsed unconscious on the tank bottom. When the Master reached the tank bottom to aid the Cadet he was overcome by hydrocarbon vapour and collapsed.
The alarm was raised and a rescue was quickly initiated. The Master and Cadet were retrieved from the bottom of the cargo tank and brought to the main deck where first aid was administered. The report concludes that the Master died and the Cadet was injured as a result of entering the cargo tank containing a concentration of hydrocarbon vapour at the bottom of the cargo tank. The ship’s safety procedures for enclosed space were not fully complied with and the risk posed by the hydrocarbon vapour measured in the cargo tank was not appreciated by those involved in the tank entry preparations.
The report also concludes that opportunities were missed on board to stop the tank entry by several crew members and that the death of the Master could have been prevented had the safety procedures on board been followed in full.
The full report can be found at gov.im/lib/docs/ded/shipregistry/formsdocs/reports/casualty/iompg12.pdf
Source:IMCA
The Chief Officer and Cadet entered the cargo tank after an enclosed space work permit and risk assessment had been completed. When the Chief Officer and Cadet reached the bottom of the cargo tank they felt debilitating effects of hydrocarbon vapour present at the lower level of the cargo tank. Both the Chief Officer and Cadet attempted to activate their Emergency Escape Breathing Devices (EEBD) and exit the cargo tank.
The Master observed the Cadet in difficulty and quickly entered the tank, ignoring the advice of a fellow crew member. The Chief Officer successfully exited the cargo tank but the Cadet had collapsed unconscious on the tank bottom. When the Master reached the tank bottom to aid the Cadet he was overcome by hydrocarbon vapour and collapsed.
The alarm was raised and a rescue was quickly initiated. The Master and Cadet were retrieved from the bottom of the cargo tank and brought to the main deck where first aid was administered. The report concludes that the Master died and the Cadet was injured as a result of entering the cargo tank containing a concentration of hydrocarbon vapour at the bottom of the cargo tank. The ship’s safety procedures for enclosed space were not fully complied with and the risk posed by the hydrocarbon vapour measured in the cargo tank was not appreciated by those involved in the tank entry preparations.
The report also concludes that opportunities were missed on board to stop the tank entry by several crew members and that the death of the Master could have been prevented had the safety procedures on board been followed in full.
The full report can be found at gov.im/lib/docs/ded/shipregistry/formsdocs/reports/casualty/iompg12.pdf
Source:IMCA
Subscribe to:
Posts (Atom)