Safety Alerts 15

Chemicals

• Liquid propane: Stored for refrigeration is a ‘bomb’. Leakage leads to fire/ explosion/ BLEVE

• LP Production header: 10’ long corrosion rupture, below a demulsifier injection point without injection quill. The quill would have introduced the chemical into the middle of the flowing stream, avoiding localized corrosion. Check injection points 

• Methanol: Gravity fed from a portable tank to platform storage tank. The feed hose had a split and was duct taped. Hose opened and sprayed methanol. It was ignited by GT exhaust

• Methanol: Damaged metal roof over a methanol tank was being removed. Sparks from the cutting torch ignited tank vent vapours. Methanol vapours had corroded the tank aluminium flame arrestor, allowing flame flash back into the tank. Explosion and fire. Note: Tank had PVC piping rather than steel

• Mercury: in natural gas can cause LMR (Liquid Metal Embrittlement), a rare but instantaneous failure of Aluminium Cold Box. Rupture, release and explosion

• Mercaptan: Cleaning chemicals (bleach? NaOCl?) used to clean Odorizer produced reactive chemicals that exploded

• Triallyl Cyanurate: First batch of a new product. Runaway reaction released flammable and toxic Allyl Alcohol and Allyl Chloride via manway seal and rupture disk. Undersized cooler, inadequate vent gas disposal, poor hazard analysis, start-up planning and emergency response

• Dye Production: Runaway reaction blew the reactor hatch. Violent explosion and fire. Inadequate cooling. Undersized rupture disks. No temperature or pressure alarms, automatic shut- down facility or dump/quenching reactants

• Acrylic polymer: 12 % more than normal batch. All the monomers were added. Next, the solvents (toluene and cyclohexane) and the initiator were added. Then part of the extra 12% more monomer was added - though the additional monomer for the larger batch was in the initial charge. Then the contents were heated and the initiator solution was added. Due to runaway reaction vapour vented from the reactor manway, forcing the operators out of the building. Building then exploded. Inadequate cooling. Fouled condenser that was not inspected or cleaned of sediment, scale and rust in its 30 years of service

• Polymers: Solution of di-amines and di-carboxylic acids through a series of reactors. Partially reacted waste diverted to a catch tank. Due to problems with an extruder downstream of the reactor, a start-up was aborted. Unusually large amount of partially-reacted material reached the catch tank. Hot molten polymer in the catch tank continued to react and decompose, releasing gas and foam. Foam filled the tank reaching external pipes, and vents. The catch tank was under pressure. When operators, unaware of the inside pressure, partially unbolted its cover, it blew off rupturing nearby piping. Hot fluid ignited. Fire. Unable to read catch tank pressure; and fouled/ blocked relief valve inlets

• Mononitrotoluene: Produced by reacting toluene with nitrating acid. The resulting MNT, residual acid, toluene, and water were separated, spent acid concentrated and recycled. Toluene stripper removed residual toluene. MNT liquid was separated in a 3 column distillation unit into ortho-, meta-, and para-MNT. The column operated under vacuum. The plant was shut down following a series of incidents including a fire in a hydrogen unit and loss of vacuum in the distillation unit with MNT. After a month, the plant was restarted and column bottom temperature steadily increased. Vapor generated accumulated on the chimney tray at column top, resulting in a tray high-level alarm. The column ruptured and its top was blown away. Column wall fragments hit a storage tank. Fire. Unit cooling tower was struck by debris and caught fire. Reboiler leaking steam valves had cooked MNT in column top, releasing gases and pressurizing the column. No high temperature/ pressure alarm

• Cleaning chemicals: Mixing 2 different types may lead to toxic fumes. Check. And make sure equipment are free of chemicals after a cleaning operation

• Chemicals stored for a long time may degrade and lead to explosion. May impair the ability of inhibitors or stabilizers

Offshore

• FRP deck gratings are load tested under cellulosic fire that have slow growth times and may reach a temperature of 880°C after 60 minutes vis-à-vis hydrocarbon fires at 1100°C. Jet fires produce still higher temperatures in shorter times. FRP gratings may lose strength/ fail under hydrocarbon fires. While gratings may appear OK post-fire, may have insufficient strength to support the dynamic loading arising from persons walking/running over

• Dropped objects. Based on weight/ type of object deflected angle varies. Impact radius is based on angle and water depth

• 14” Subsea pipeline severed by dropped anchor. Pipeline didn’t shut as its PSLL is set very low. SDVs on 2 incoming lines were in branches

FPSO/ SemiSub

• SemiSub sank: Leaking inlet valve caused an Emergency Drain Tank in Starboard Aft Column (right rear leg) burst on overpressure. Firewater piping burst. FW header PSL started FW Pumps, flooded the column making semisub list and finally sink. Study impact of FRP pipe rupture, how water flow is drained without flooding + effect of auto start of large FW pumps in case of pipe rupture. Avoid HC tanks in legs

• Oily water and oil released when a spec blind was opened in a drain connection of a vessel not in use for a long time. Severe weather induced FPSO movement had caused residual liquids to migrate from another section of the closed drains system that had not been emptied

• Cargo vent: Inert + flash gas ignited at mid flare structure. Heat surface damage to braces. Position vent tip to face away from braces. Add flame detector (thermocouple) at tip + fire suppressant. ESD3 on fire. New designs: Assume vent will ignite at full load and locate tip accordingly

• Storm broke of a few mooring lines (anchor chains). FPSO moved. Subsea wells shutdown. Gas lift risers ruptured and fell to sea

• Mooring systems failure. Poor manufacturing procedure + poor material handling during installation