Topic
Hydrogen Sulphide
Exposure, detection and control of hydrogen sulphide gas.
Documents
- 202623 Feb
PEMEX Deer Park Chemical Release
CSB investigation of a fatal hydrogen sulphide release during refinery maintenance in Deer Park, Texas. Workers opened the wrong flange on active piping. The report examines equipment identification, permit scope and hold points, interacting maintenance operations, contractor reassignment and operational discipline, recommending clearer marking and work authorisation arrangements.
- 2025Nov
PPE only works when you wear it correctly! — Process Safety Beacon, November 2025
This Beacon examines a California refinery release during pressure-gauge replacement, where ineffective isolation and absent respiratory protection increased harm from hydrogen sulphide exposure. It explains limitations of personal protective equipment and stresses task-specific procedural requirements, correct use, pre-use inspection and regular checks of condition and respirator cartridge expiry.
- 202529 Apr
Hydrogen Sulphide (H2S) detected onboard vessel
A vessel-wide odour prompted crew to investigate with gas detectors but without respiratory protection. Hydrogen sulphide reached a measured 170 ppm in the Grease Trap room, entering through a dry drain trap. The flash examines sewage-system maintenance, incomplete procedures and risk assessment, and subsequent revisions to tank-flushing, drain-trap and emergency arrangements.
- 202520 Mar
Fatal accident on board bulk carrier Berge Mawson with loss of 3 lives
MAIB investigates three stevedore deaths in Berge Mawson’s coal cargo hold access space. The report considers a fatal atmospheric mechanism highly likely, while noting that medical causes were unconfirmed. It examines pre-entry gas testing, permits, access security, warning comprehension, training and rescue arrangements during cargo operations.
- 202418 Jun
Personnel exposed to hydrogen sulphide during maintenance
Subcontractors encountered hydrogen sulphide during annual acid-filter maintenance in a vessel’s well treatment system room. Re-entry after an All Stop led to alarms indicating 357 ppm; no adverse health effects were reported. The flash identifies residual water and chemicals and broken pressure gauges, and emphasises evacuation, reporting and safe re-entry.
- 202327 Nov
Case study: Confined space fatalities due to hydrogen sulphide
Three people died during gas sampling in a jack-up rig’s spud can; a standby worker survived exposure outside the opening. The summary links circumstantial evidence to hydrogen sulphide inhalation and examines unsuitable SCUBA equipment, restricted ventilation, unprotected rescue and contractor assurance. Proposed training covers monitoring, correct breathing apparatus and emergency response.
- 202327 Nov
Case study: Saturation diver fatality due to hydrogen sulphide
This safety flash summarises a historical saturation-diving fatality during inspection of a leaking sour-crude pipeline in the Bombay High oilfield. Hydrogen sulphide in the bell caused collapse; the diver subsequently drowned. It discusses possible gas-entry routes, absent gas detection, bell-to-bell rescue and the potential use of ROVs for surveys.
- 20232 Nov
H2S released during rig reactivation activities
During quayside rig reactivation, hydrogen sulphide escaped from a machinery-space bilge water tank after its top hatch was removed, threatening nearby personnel. The alert describes acute inhalation dangers, including immediate collapse at concentrations above 1,000 ppm, alongside steel corrosion and flammable or explosive concentration limits.
- 202322 May
Unexpected H2S Detection at Offshore Facilities
This alert summarises unexpected hydrogen sulphide detections at offshore facilities producing from fields classified as H2S absent. Cases involve production equipment, cargo tanks, defoamer transfer and ballast-tank cleaning. BSEE recommends considering atmospheric testing, stagnant-tank inspections, crew drills, routine sampling and risk assessments addressing bacterial generation of the gas.
- 2023May
Hydrogen Sulfide
Regulatory inspection questions address areas classified as hydrogen sulphide present or unknown. They cover contingency plans, training, drills, gas detection, respiratory protection, ventilation and medical equipment. Further checks address soluble sulphide testing, well-control fluid treatment, flaring, detector testing intervals and corrosion-resistant materials during well and production operations.
- 2023Apr
High concentration of hydrogen sulfide (H2S) in cargo and slop tanks
This HSE safety notice addresses hydrogen sulphide in FPSO and FSU cargo and slop tank ullage spaces, including concentrations beyond standard portable instruments’ measuring limits. It discusses exposure during monitoring and releases, corrosion risks, suitable gas monitoring, revised risk assessments, integrity inspection and crew training.
- 202316 Feb
Fluid Transfer Transport
Hazard alert addressing toxic and flammable vapours, hydrogen sulphide and oxygen displacement during vacuum loading and offloading of produced fluids. It assigns responsibilities to facilities, hauling companies and drivers, covering atmospheric monitoring, training, conductive hoses, bonding and grounding, safe vent discharge and prevention of diesel-engine runaway.
- 2023Jan
Hydrogen Sulfide Release
This fatality alert describes hydrogen sulphide poisoning that killed a worker responding to a pump alarm and, later, his spouse at an oil production facility. It examines defective gas detection, missing detector-use policies, inadequate isolation arrangements and visitor access, alongside recommendations for lockout/tagout, ventilation assessment and detection-system assurance.
- 202125 Nov
Hydrogen sulphide detected in a bilge tank
A vessel crew stopped bilge-water transfer after noticing a rotten-egg smell; a multi-gas meter detected 453 ppm hydrogen sulphide at the vent. The flash describes accumulated tank residue, delayed specialist cleaning, gas routing away from accommodation, continuous monitoring and respiratory protection, alongside lessons on machinery-space cleaning practices.
- 202121 May
Aghorn Operating Inc. Waterflood Station Hydrogen Sulfide Release
This investigation summary examines a fatal hydrogen sulphide release at an Odessa waterflood station that killed an employee and his spouse. It identifies a broken pump plunger, while leaving failure timing unresolved, and examines detector nonuse, missing lockout procedures, inadequate ventilation, detection and alarm failures, and deficient site security.
- 20218 Apr
H2S Alarm Activation
An alert describes hydrogen sulphide detection at surface during drilling of a well’s casing shoe track, upon bottoms up. The previously cemented well had been suspended for 30 days, with untreated spacer fluid remaining inside the casing. Rig and mudlogging sensors near the shale shakers recorded 57 ppm and 43 ppm respectively.
- 202010 Jan
Crew member fainted after working in water ballast tank
A crew member collapsed after removing sediment and rust from a ship’s water ballast tank. Treatment addressed suspected hydrogen sulphide poisoning, but subsequent atmospheric tests found no harmful gases. The flash identifies shortcomings in hazard awareness and risk assessment, recommending space-specific assessment and effective briefings despite prior ventilation and personal monitoring.
- 201924 Sep
Safety Alert 366 - Dangerous Levels Of H2S Detected At Offshore Facilities
BSEE describes three hydrogen sulphide releases during offshore pipeline flushing and well abandonment, including incidents at non-sour facilities. One worker experienced dizziness and nausea. The alert recommends considering gas monitoring, detector calibration and bump testing, job safety analysis, rescue preparedness and gas-buster safeguards during potentially hazardous operations.
- 201928 Jan
Confined space entry: Person overcome by fumes and rendered unconscious
A vessel crew member cleaning a faulty sewage-tank sensor was overcome by hydrogen sulphide, lost consciousness and fell from a fixed rack to the deck. The flash identifies failures in risk assessment, work authorisation, atmospheric checks and maintenance procedures, and reinforces safe systems of work and awareness of gas hazards.
- 2018
Fatalities in Oil and Gas Extraction (FOG) Special Topic Report 2018
NIOSH summarises eight fatalities and ten hospitalisations during 2015–2016 involving ignition, inhalation or suspected inhalation of hazardous gases and vapours during fluid handling at oil and gas sites. Tables distinguish exposures, fires and explosions, activities, fluids and reported outcomes, including cardiac deaths with possible work exposure.
- 201730 Nov
Limitations of Monitors Hazard Alert
This hazard alert explains multi-gas monitor selection and use in oil and gas operations. It highlights hydrogen sulphide monitor limitations, unreliable flammable-gas detection under some atmospheric conditions, and misleading alarm cessation. Guidance covers sensor selection, calibration, bump testing, breathing-zone positioning and immediate evacuation following any alarm.
- 20173 May
Near-miss: Gas release from subsea pipeline
A gas release occurred during subsea spool connection while divers were in the bell for shift changeover. The vessel moved clear and an ROV released the crane hook safely. Findings highlight missing refinery communication about valve opening; recommendations address permit understanding, inter-site communication, H2S preparedness, drills and equipment testing.
- 201628 Sep
Hot Work Hazard Alert
This hazard alert addresses fire, explosion and toxic exposure during hot work on oilfield tanks and equipment containing hydrocarbon residues. It warns against treating empty equipment as safe and sets out employer and worker responsibilities for permits, atmospheric monitoring, tank cleaning, ignition control, protective equipment and hazard training.
- 201413 Mar
Loss of consciousness due to exposure to H₂S
Two mechanics lost consciousness and a third became dizzy after hydrogen sulphide escaped during high-pressure water cleaning of a sewage tank. All recovered. The flash identifies omitted toxic-gas hazards, absent gas detection and inadequate planning, and discusses permits, revised procedures, training and confined-space precautions.
- 201225 Jan
H₂S leak umbilical laying
A hydrogen sulphide leak during umbilical laying prompted work stoppage and area isolation after deck personnel noticed a rotten-egg smell. Specialist air testing preceded resumption, with no contamination or illness reported. The flash identifies missing awareness and recommends testing before and during deployment, and halting operations if leaks occur.
- 2011Aug
OCE6 - Hydrogen sulphide
This offshore COSHH information sheet addresses hydrogen sulphide exposure through area classification, gas detection, isolation, ventilation and respiratory protection. It specifies positive-pressure breathing apparatus, equipment checks and testing intervals, alongside emergency planning, rescue training and supervision. Detection arrangements differ according to area category and process-stream concentration.
- 20114 Jul
Confined space – multiple fatalities
A bosun fell into a vessel’s slop tank for unknown reasons. Two colleagues entered to help, and all three became unconscious. Subsequent rescue used ventilation, atmospheric testing and breathing apparatus. The bosun died; both colleagues recovered after hospitalisation. Investigation noted impulsive rescue entries and inadequate understanding of hydrogen sulphide accumulation.
- 2011Mar
OCE13 - Breaking containment – process cleaning operations
Guidance for internal cleaning of offshore process plant addresses exposure to hydrocarbons, hydrogen sulphide, mercury and naturally occurring radioactive material. It describes isolation verification, draining, purging, gas testing, respiratory protection and exposure monitoring, alongside decontamination, waste handling, health surveillance and worker training.
- 2011Mar
OCE7 - Pigging operations
This offshore guidance addresses exposure control during pigging, including benzene, hydrogen sulphide and radioactive residues. It describes receiver depressurisation and venting, gas monitoring, conditional respiratory protection, protective clothing and cleaning arrangements. Maintenance, personal exposure monitoring, dermatitis surveillance and worker training support the recommended controls.
- 201031 Mar
The back-loading and carriage of hazardous oil contaminated bulk cargo on offshore supply vessels
This alert addresses hazardous oil-contaminated waste carried in offshore supply vessel mud tanks following reports of hydrogen sulphide and explosive atmospheres. It sets out pre-loading analysis, trained testing, hazard documentation and segregation measures, alongside restrictions on mud-tank use for fluids from wells with open perforations.
- 2009Mar
Fatality caused by unloading the wrong chemical into a storage tank! — Process Safety Beacon, March 2009
A chemical delivery was directed to the wrong storage tank without checking the shipping papers. Mixing sodium hydrosulphide with ferrous sulphate generated toxic hydrogen sulphide, killing the driver. The bulletin stresses material identification, unloading procedures, personnel training and clear labelling, and suggests considering connections designed to hinder unloading mistakes.
- 20043 Aug
H2S Inhalation: Man Fell from Tote Tank Resulting in an LTI
This alert describes hydrogen sulphide inhalation and a fall from a tote tank during waste-fluid transfer on deck. After hearing laboured breathing and losing radio contact, the engine room operator activated the emergency stop and checked the worker, finding him face down with visible signs of head injury.
- 2003Sep
Environmental Enterprises Hydrogen Sulfide Release — Environmental Enterprises Case Study
This case study examines a hydrogen sulphide exposure during hazardous-waste treatment in Cincinnati. Sodium sulphide and polyaluminium chloride reacted in an open clarifier with inadequate air mixing, injuring one employee. It analyses operating instructions, training, hazard communication, detector maintenance and management oversight, and describes subsequent improvements.
- 2003Jan
Georgia-Pacific Corp. Hydrogen Sulfide Poisoning — Final Investigation Report
Investigation of fatal hydrogen sulphide exposure at Georgia-Pacific’s Naheola pulp mill in Alabama. Sodium hydrosulphide entered an acid sewer and reacted with sulphuric acid, releasing gas through a manway seal. The report examines reactive-hazard identification, sewer modifications, operating procedures, respiratory protection and emergency decontamination, including secondary exposure of medical responders.
- 200116 Oct
Man Downed by H2S Gas
A well-service rig worker was overcome by hydrogen sulphide during a pump-down stripping job. As the well came in, he attempted to fit a stabbing valve to stop the flow. Operations were immediately suspended, and the worker was taken to hospital.
- 20005 Dec
Near Miss – Frozen Air Regulator
A rig in a cold environment experienced failure of its breathing-air cascade supply while personnel wore work masks because of high hydrogen sulphide levels. Personnel switched immediately to five-minute escape units and evacuated the rig. No injuries were reported.
- 200010 Jul
Safety Alert 16 - Rupture Of Sour Gas Piping
An offshore sour-gas piping rupture released natural gas containing hydrogen sulphide without injury. Earlier ultrasonic testing had identified serious corrosion near the failed elbow, but no corrective action followed. The alert recommends detector testing and breathing-equipment familiarity during drills, and asks operators to consider periodic ultrasonic inspection, prompt results review and predetermined wall-thickness limits.
- Undated
Hydrogen Sulphide Released from Ruptured Glycol Vessel Piping
This investigation records a hydrogen sulphide gas release from ruptured three-quarter-inch piping attached to a glycol vessel on Platform Hidalgo’s production deck. The vessel operated at approximately 1285 psi with approximately 19,500 ppm H2S. Gas detection initiated an alarm and emergency shutdown; similar piping was undergoing ultrasonic non-destructive inspection.
- Undated
Produced-Water Leak from Float-Cell Drain Header with H2S Alarms
An investigation records a produced-water leak from a corroded float-cell drain header, accompanied by H2S alarms. Personnel isolated the equipment, temporarily patched the header and mustered with breathing apparatus. No injuries occurred. The report identifies inadequate maintenance and records replacement of the piping and implementation of a more detailed corrosion plan.
- Undated
Hydrogen Sulphide Detected During Dewatering Following Hurricane Recovery
Investigation of hydrogen sulphide detected during dewatering at Cognac following hurricane recovery work. Analysis linked the gas to bacterial activity beneath oil-coated deposits that chemical treatment had not reached. The report records shutdown, atmospheric checks and recommendations for revised de-oiling procedures, biocide circulation and bacteria testing before dewatering.
- Undated
Hydrogen Sulphide Release Through Corroded Piping During Pigging
BSEE investigates a hydrogen sulphide release during pigging at Main Pass 299-FP. Exterior corrosion compromised scrubber outlet piping; inadequate routine corrosion maintenance was identified as the primary cause. The report describes repeated alarms, mustering, breathing apparatus use and leak detection. Internal corrosion was not confirmed.
- Undated
Hydrogen Sulphide Vented into Platform Wellbay Following Gas Blow-By
An investigation describes hydrogen sulphide venting into the wellbay on platform Gail following gas blow-by to a slop tank. Failure of separator level controls to close a valve was identified as the probable cause, with polymer deposits contributing. The report recommends keeping the drain pot valve closed.
- Undated
Hydrogen Sulphide Release During Pipeline Flushing for Platform Abandonment
Investigation of a hydrogen sulphide release during pipeline flushing for platform abandonment at South Pelto 5-B. Detection of 100 ppm prompted cessation of operations and muster on a neighbouring lift barge. The report attributes gas formation to bacterial growth in retained pipeline water and records tank neutralisation without injuries or ill effects.
- Undated
Hydrogen Sulphide Release During Condensate Rerouting
Investigation of a hydrogen sulphide release on Hidalgo platform during condensate rerouting. Opening the wrong valve, combined with a check valve lacking a positive seal, allowed condensate into deck drains. Five workers received medical care and were evacuated. Corrective measures included locking the valve, documenting procedures and planned pipework alterations.
- Undated
Hydrogen Sulphide Exposure During Orifice Plate Change
Investigation of hydrogen sulphide exposure during an orifice plate change at MP 299-B. A leaking meter-run gate released gas, repeatedly overcoming the lead operator, who fell through the ladder cage. The report identifies absent job analysis, monitoring, respiratory protection and mentoring, and records operator measures to prevent recurrence.
- Undated
Hydrocarbon Release During Well Workover and Completion
Investigation of a well-control incident during workover and completion on Platform Gail. Removal of a wellhead lockdown pin bypassed the BOP system, while discontinued fluid pumping allowed an underbalanced condition. The report describes hydrocarbon release, hydrogen sulphide readings, evacuation and an approximately three-gallon oil spill, with recommendations on well-control practices and training.
- Undated
2012-104 Investigation of February 23, 2012, H2S Gas Release Platform Hidalgo, OCS-P 0450 Pacific OCS Region
Investigates a hydrogen sulphide release at Platform Hidalgo offshore California, with no reported injuries. Examines failed pipework, oxygen contamination and elemental sulphur formation, alongside limitations of point-specific ultrasonic inspection. Includes radiographic follow-up, thickness-monitoring arrangements and five-year inspection recommendations, plus historical Hermosa findings and emergency-response recommendations.
- Undated
Equinor – Gullfaks C – investigation of fractures in coiled tubing
PSA investigates coiled-tubing fractures during well clean-out following hydraulic fracturing at Gullfaks C. The report identifies hydrogen-sulphide-induced sulphide stress cracking and examines chemical compatibility, planning and risk communication. It describes well securing through the blowout preventer, deck personnel exposure during waste treatment, and shortcomings in applying previous incident experience.
- Undated
Release of cargo vapours on chemical tanker Jo Eik with 2 people exposed to fumes
Investigation synopsis of cargo-vapour exposure aboard Jo Eik at Teesside during mandatory tank pre-washing with portable equipment. Vapours escaped through an open Butterworth hatch and accumulated in an unrecognised enclosed deck area. It examines cargo hazard information, rescue without breathing apparatus, defective washing systems and recommendations for communication and respiratory protection.
- Undated
Sodium Hydrosulfide: Preventing Harm — Safety Bulletin - Sodium Hydrosulfide: Preventing Harm
This advisory bulletin explains sodium hydrosulfide hazards, including hydrogen sulphide generation through acid mixing or excessive heat. It reviews reported US incidents from 1971 to 2004 and discusses storage containment, exposure prevention, spill response, respiratory protection and rescue precautions, with case accounts of incompatible transfers and releases.
- Undated
Toxic fumes from refrigerated sea water tank on pelagic freezer trawler Atlantic Princess affecting 9 people with loss of 3 lives
This inquiry examines three deaths and six injuries aboard Atlantic Princess off Mauritania when contaminated refrigerated seawater tank contents released toxic gas onto the ramp deck. It analyses fish spoilage, tank emptying, cleaning, ventilation and rescue attempts, supported by laboratory simulations, and recommends design improvements, operating procedures, monitoring and crew training.