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Optimizing Flare Operation Through Proper Design - Chemical Engineering
Optimizing Flare Operation Through Proper Design - Chemical Engineering: Flares play a critical role in many CPI facilities, to manage hydrocarbon emissions. To improve operating safety, protect personnel and the environment, and avoid costly shutdowns, molecular seal systems must be properly designed, operated and maintained. Follow this guidance to get the job done right.
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January 12, 2023
AMMONIA SHIP UNLOADING INCIDENT
Summary of incident
On 21 July 2018, a major release of ammonia gas occurred at a Western Australian port.
As
part of a standard operation, an ammonia tanker vessel was supplying
anhydrous ammonia to a process plant. Following the completion of liquid
ammonia unloading, purging of the loading arm and pipework was
commenced with ammonia gas supplied by the ship via the onboard storage
tank head space.
While the purging operation was underway, an
operator inadvertently partially closed a line valve. As the line valve
was no longer fully open, a control signal was sent to the plant
emergency shut-down (ESD) valve to trip closed.
This resulted in
increasing internal pressure and hydraulic hammer in the loading arm,
creating significant forces against the loading arm quick
connect/disconnect coupler which was not sufficiently tightened for the
conditions. These forces caused the loading arm to decouple from the
ship’s flange and release ammonia gas. Ammonia continued to flow from
the ship manifold until the ship crew manually tripped the ship’s ESD
system. The release was estimated to be 1200 kg over 24 seconds.
Five
personnel present at the jetty were taken to the hospital for medical
examination or assessed by ambulance services. All were released the
same day.
Direct factors
The loading arm quick connect/disconnect coupler disconnected from the ship due to internal pressure.
Contributory factors
The unloading of ammonia was completed without correct engagement of the coupler. This can be attributed to:
- insufficient written instruction provided
The standard operating procedure provided little detail on the correct process for the coupler engagement.
- the control panel provided ambiguous information
A
green indicator lamp on the control panel indicated that process to
engage the coupler was starting. This indicator can be misconstrued as
meaning full engagement has been achieved.
- there was no procedural system to validate the coupler engagement prior to commencing ship unloading
There was no visual check to confirm that the two indicator lines aligned as per the manufacturer’s instructions.
- there was no interlock to prevent unloading unless the coupler was fully engaged.
The process relied on procedural controls.
There was full reliance on the coupler installation with no secondary back-up system.
At
the flange connection, there was only one control measure to ensure
continuity of attachment. As the coupler is an electric-hydraulic
system, various faults in the system could result in a loss of
connection.
Hazard identifications and risk assessments did not
adequately identify all reasonable control measures for the interface
between the ship and the plant.
Manual intervention by a third party
was required to stop the flow of ammonia from the ship. There was no
automated system to shut the supply of ammonia from the ship in the
event of a plant emergency at the time of the incident.
Actions required
To
ensure similar incidents do not happen, the following actions are
recommended for all operations involving quick connect/disconnect
couplers.
Ensure the quick connect/disconnect coupler is correctly engaged by:
- confirming the standard operating procedure provides adequate written instructions
- attending periodic refresher training from the vendor
- implementing checklist hold points to confirm critical systems are in place prior to unloading
- installing transducers on the coupler and interlock with the safety system.
Install a locking mechanism on the coupler to ensure it cannot be inadvertently decoupled.
Review
and revise the hazard identification and risk assessments to ensure all
reasonable control measures are in place at the interface with third
parties. For ship transfers:
- install a ship to shore safety shutdown system to automatically close the ship manifold valve in the event of a plant ESD.
Revise competency and refresher training for all personnel working with couplers.
SOURCE: https://www.dmp.wa.gov.au/Documents/Dangerous-Goods/DGS_SIR_0119.pdf
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A spotlight on IoT-enabled predictive maintenance
Texmark Chemicals ushers in the Refinery of the Future
A spotlight on IoT-enabled predictive maintenance
In an industry with a long history of reluctance to change, Texmark Chemicals, with the help of Deloitte, embraced digital innovations such as the industrial Internet of Things (IoT), a new technology in the chemical industry, to drive profitability and create a repeatable use case in predictive maintenance IoT.
