Safety Alerts 16

Chemicals

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

• Cleaning: 2” blind was being removed to install piping taken out for cleaning. Corrosive silicon tetrachloride liquid leaked past an isolation valve and splashed. Chemical burns. Failure to isolate, flush, drain and check the piping system. CSB

• Cleaning: Operators were preparing acid cleaning solution to circulate and remove solids buildup in process equipment. An operator standing on top of acid tank, poured Sulfamic acid (H₃NO₃S) powder into its opening. The tank was supposed to contain water, but a valve inadvertently left open allowed “weak wash” process stream to enter the tank. The weak wash contained Sodium Sulfide that reacted with Sulfamic acid, generating H2S. Caution about H2S. CSB

• Chlorine: Used to treat cooling water. Assuming a container was empty, its hose was disconnected. Container was 62.5% full. Cl2 escaped. Add a weighing scale / PG/ use alternate chemicals like bleach. CSB

• Chlorine: Exposure ~ without donning SCBA; removing SCBA prematurely; continuing to work in the contaminated area. Absence of monitors and alarms. BP

• HCl: Leak from a preflash tower formed HCl acid on contact with moisture in atmosphere. Corroded bolt threads of a sample point in the overhead line and ejected the sample point. Light HC release. BP

• HCl: Transferred from a truck using compressed air. Air pressure created cracks in truck's internal lining and acid reached the metal shell and attacked it. Leak. Pump out. BP

• Caustic: Spent Caustic being transferred to a portable tank erupted via its unsecured top hatch. Injury. CSB

• Caustic: NaOH was mixed in a mixing barrel in the mud area of the drilling rig. After mixing 22 kg first, a second sack was added into the same solution. Violent reaction, spraying the mixture out. Injury. BP

• H2SO4: Instead of refilling with Aluminium chloride a vessel was filled with Sulfuric acid. Resulting HCl vapor pressurized the tank and ruptured it. CSB

• H2SO4: Sulfuric acid was wrongly filled into Sodium Hypochlorite tank. Chlorine gas release overwhelmed the truck driver. He was unable to close the truck or the tank fill valve. Gas entered the control room too. Use different type and size of fill connections

• Cyanide: While working in a cyanide area, a worker accidentally nudged open a ball valve on an adjacent pipe. Some ACH (Acetone Cyanohydrin) fell on him, unknown to him. Fatality. Similar, another worker who was exposed to ACH contaminated waste water. BP

Catalysts

• Unregenerated catalyst: Normally self-heating and often pyrophoric. Handle with care. BP

• Catalyst dumped from a reactor under N2 pressure, overflowed the bin and the pile caught fire. BP

• CoMo catalyst in the oxide form, not in its Sulfide form was loaded in HDS reactor. Runaway reaction and bulged bottom head of reactor. Leak in reactor outlet fire that caught fire. BP

• Mol Sieve due for replacement. First purged with hot residue gas with 830 ppm H2S, cooled by N2 and then dumped into a truck; kept wet to avoid pyrophoric combustion. As mol sieve had more affinity for water than H2S. Released H2S. Fatality - 3 persons levelling the pile in the truck. BP

• Catalyst was being removed by vacuum sucking. Catalyst pile caved in burying the worker. As air leaked from his breathing air supply line, some of the catalyst ignited. BP

• While loading catalyst to the bottom bed of a HDS reactor, a longer than recommended sock was used. It was unable to support the weight of the catalyst and fell on the worker. Fatality. Use hard pipe and limited length of flexible sock. BP

• While removing catalyst from a CO converter, poor seal around the air mask, resulted in N2 penetration, loss of judgement. Fatality. BP

Offshore

• FRP Deck Gratings: Usually 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

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 and further 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 were 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 vent tip accordingly

• Storm broke 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

Refinery

• Light ends: Are volatile. Are stored under pressure and/or low temperatures. Heavier than air and spread along the ground. Liquids vaporize and form a large vapor cloud. Easily escape thru flange joints, packings and seals. On boiling, low temperatures result in freezing and blockage/ breakage; hydrates and blockage. High coefficient of thermal expansion with potential rupture. BP

• CDU: Desalter. During hydrotest, a porcelain insulator shattered at the clamping point. Excess tightening. Sight glass, not rated for the pressure, failed. BP

• CDU: Desalter. RV lifted when Desalter Crude Oil Pump tripped, damaging its balanced bellows. Similar, when the feed rate was reduced during start-up to attend to leaks from 2 HX, RV lifted and flange leak from its bypass (vent) valve. Fire. BP

• CDU: After gas testing, column top section was being inspected while hot work was done on a 50” overhead line. The column 50” nozzle was not blinded. Internal deposits/ flammable liquids in the outlet caught fire, sending dense smoke and asphyxiated 2 of the workers in column top section. BP

• CDU: While removing a 42” blind on top, flash fire from fuel gas that entered from flare header and ignited by temporary halogen floodlights. BP

• CDU: Incorrect MOC. Elbow failed. Pool fire. 3 days later, column structurally failed due to internal fire as a result of air ingress + pyrophoric material and oil in the column

• CDU: Piping support directly welded to column without any reinforcement plate, vibrated due to two phase flow and fatigue failure. BP

• CDU: Pipe thinned by sulfidation corrosion. Rupture. Corrosion at a uniform rate over a larger area

• CDU: Earthquake toppled a 94m tall concrete chimney. Fire in CDU, reformer and tank farm

• CDU: Flash floods filled SWD and spread HC around. Ignited by Coker furnace still cooling down. Fire in CDU and DCU. Similar in another refinery. Storage Tanks too exploded

• CDU: Watch out for Naphthenic Acid, Wet H2S, Caustic damage. Caustic stress corrosion ripped a 20” feed line upstream of pre-heat HX train due to an incorrectly positioned injection quill. BP