3 Employees Killed, 2 Injured By Hydrogen Sulfide Exposure

 Employee #1 was inside a frac tank shoveling residue (called BS) to one end of the tank for subsequent vacuuming and removal. As he completed the task, the tank was washed down with waste water containing hydrogen sulfide. Approximately 8 minutes following the waste water entrance, Employee #1 collapsed from exposure to the chemical. Employee #2 entered the tank and attempted to rescue Employee #1, but he too collapsed. Apparently Employees #3 and #4 entered the tank and attempted a rescue and but succumbed also. Employee #5 attempted to revive Employee #1 through an opening at the end of the frac tank. He was affected by the hydrogen sulfide gas but was able to call the city's first responders. Employees #1, #3, and #4 died of hydrogen sulfide exposure. Employees #2 and #5 were hospitalized. 

Source:Osha.gov

EXPLOSION IN SALT WATER TANK

At approximately 2:30 a.m. on July 30, 2011, Employee #1 was working the night shift at a saltwater disposal facility. Specifically, the facility specializes in the disposal of salt water that is contaminated with field oil waste. The water would usually be separated from the oil and petroleum based materials in a settling tank. The water would then pumped back into the ground through an injection well, while the oil based material is gravity drained into a series of collection tanks. The oil would then sold to oil recyclers. During Employee #1's shift, he was monitoring two oil collection tanks that were connected to a separation drum tank. 

The first of the two tanks was also connected to the second tank to allow for spillover as the amount of liquid rose. Under normal operation, the tanks would take several days to become full; however, facility operators would frequent the catwalk area that was accessed by way of a ladder to gauge the tanks levels. After receiving a water delivery from a full tanker-truck, Employee #1 accessed the catwalk to gauge the water level. Soon after reaching the tank area, an explosion occurred. The truck driver, who was leaving the facility, observed the explosion and following fireball in his rear view mirror. The driver immediately stopped his truck and contacted emergency services. Despite the fire spreading to both tanks, Employee #1 was able to escape the fire crazed area; however, his clothes were completely burned off and over ninety percent of his body was burned. Employee #1 collapsed on the front porch area of the facility office, where emergency personnel, a short time later, began treatment. Employee #1 was taken by helicopter to Ardmore Hospital, where he died. The accident investigation revealed that Employee #1 had a history of smoking near the storage tanks and had been warned by the employer to stop several times. 

Source:Osha.gov

"Sewage systems on vessels are known as Marine Sanitation Devices (MSDs) or Collection, Holding and Transfer Tanks (CHTs). Cleaning these systems is required for operations such as routine surveys and surface preservation, equipment modification, repairs and maintenance. Entering and cleaning
sewage tanks, piping and components present specific hazards to workers that put them at risk for injuries and illnesses if they are not properly protected (29 CFR 1915.13).
Workers are often exposed to dangerous atmospheres during tank opening and venting; manual pumping and stripping; breaking or dismantling components and piping; and pressure
washing, mucking, and scaling (29 CFR 1915.11(b); 1915.12). A dangerous atmosphere may expose workers to the risk of death, incapacitation, injury, chronic or acute illness, or impaired ability
to escape unaided from a confined or enclosed space (29 CFR 1915.11(b)). When working on CHTs/MSDs, special attention should be given to good hygiene practices, proper use of personal
protective equipment and safe confined space entry procedures (29 CFR 1915.88; 1915 Subparts B & I).
The information in this document can help prevent exposing workers to the known and unknown dangers of handling treated or untreated sewage and gray water tanks during tank opening, entry,
cleaning and related operations. Related components/operations include: piping, aeration, vacuuming, settling, and treatment tanks and apparatus; sewage-contaminated water tanks or waste oil
tanks, bilges, or sumps; and valves, pumps, grinders, macerators and other contaminated equipment".

https://www.osha.gov/sites/default/files/publications/OSHA_FS_3587.pdf

Source:Osha.gov

CHLORINE EXPOSURE INCIDENT

 On April 2, 2002, Employee #1 and a coworker, employees of a water treatment plant as waste water treatment operators, were changing out five 1-Ton cylinders, located in a chlorine cylinder room. Employee #1 attempted to disconnect the yoke number two of the five 1-Ton cylinders, but a high pressure leak of chlorine gas escaped from the cylinder into his breathing zone. Employee #1 was able to immediately tighten the yoke connection, stopping the leak, but required the coworker to finish the task. With Employee #1 sitting to the side, the coworker, after a couple of attempts, was able to disconnect the yoke connection without any further chlorine gas escaping. After notifying management of the incident, the coworker drove Employee #1 to Hospital Emergency Room. Once admitted, Employee #1 was treated for chlorine gas exposure and diagnosed with bilateral lower lobe pneumonia.

 A 42-year-old laborer leak testing joints inside a 54-inch round pipe suffered fatal blunt force injuries in October 2015, when an inflatable ¿bladder¿ ruptured at a waste-water treatment plant. Inspectors from the U.S. Department of Labor¿s Occupational Safety and Health Administration found his employer failed to train him properly on the testing procedure.

Workers can be killed when employers fail to protect construction workers from the many dangers in confined spaces, said Assistant Secretary of Labor for Occupational Safety and Health Dr. David Michaels. These are among the first citations under OSH¿s new Confined Space Standard. Employers can prevent more tragedies like this one if they ensure proper training of workers and communication among multiple employers whose workers are on the same site.

In August 2015, OSHA implemented its confined space in construction standard after research showed proper safety procedures would protect hundreds of workers each year from life-threatening hazards. Hazards include the risks of toxic exposure, electrocution, explosion and asphyxiation present for workers in confined spaces such as pipes, manholes, crawl spaces and tanks. In an emergency, it can be difficult to exit these spaces quickly or for rescuers to enter safely.

The agencys investigation also found the four companies failed to continuously monitor confined spaces for atmospheric and other hazards and train workers in hazards. 

Source:Osha.gov

ARE YOU PERFORMING YOUR PSSR'S CORRECTLY?

A closure of an UV (shutoff valve) was provided in the design of the plant, to avoid two phase flow when carryover occurred.  During an abnormality, the shutdown system activated the UV but the UV did not close. The RCA revealed that the UV did not close due to excessive friction caused by the presence of construction debris left behind that prevented the UV from closing

WASTE WATER TANK INCIDENT

On September 9, 2003, Employees #1 and #2 were extending the guardrail system to the hatch and platform area on top of a tank located on the Brewery property. The tank was used for the storage of solid waste at the waste water treatment facility. The tank was 40 ft in height and 48 ft in diameter. The employees were arc welding the guardrail system, 40 ft above the ground, when an explosion occurred. Employee #1 fell to the ground receiving fatal injuries. Employee #2 fell to the inside of the tank, an opening of approximately 10 ft left due to the explosion. The tank had to be drained in order to recover the body. Employee #2 apparently died from injuries due to the explosion

Credit:Osha.gov

ARE YOU INSPECTING YOUR PILOT OPERATED VALVES CORRECTLY?

A Pilot operated relief valve failed to lift during planned recertification in the workshop. The cause of failure to lift identified as a plug fitted in the pilot exhaust port. Plug was removed from pilot exhaust port and RV functioned as intended.  On inspection of three remaining RV’s on compressor discharge, it was
found that another RV also had a plug fitted in the pilot exhaust port.

ARE YOU CONSIDERING HUMAN FACTORS DURING YOUR HAZARD IDENTIFICATION?

 An ammonia leak occurred in the machinery room of an unoccupied arena. An employee was attempting to add oil to an ammonia compressor when he observed a leak (fill hose was not attached). Approximately 200 lbs ammonia was released.
Qualified person was trained, but with minimal experience in this procedure. No written procedure was available, and an error occurred while executing the procedure. The shut-off valve type (wrench-operated,
mufti-turn, no position indicator) added complexities to the process.

Source: British Columbia Safety Authority 

WHY HAZOP STUDY IS IMPORTANT

 Approximately 200 lbs ammonia was released to atmosphere. The condenser safety valve activated due to ‘no cooling’ in the condenser while the ammonia compressor was operating. While restarting the plant after a power failure, the operator forgot to start the condenser circulating pump (which should be started before starting the compressor). The compressor was started without condenser cooling, and as a result, ammonia gas temperature began to rise, thus raising the gas pressure in the system. Eventually the gas pressure rose more than the safety valve setting, activating the safety valve which released the
ammonia to atmosphere.
The compressor’s high pressure safety cut off did not activate. The high pressure cut off is supposed to activate and shut off the compressor unit when the system senses a high pressure condition.

Source: British Columbia Safety Authority 

ARE YOU SPECIFYING PRESSURE GAUGES CORRECTLY?

 Approximately 100lbs ammonia was released into an unoccupied processing room of an industrial facility when a pressure gauge failed on the liquid line to an ammonia evaporator. Inspection revealed that a second pressure gauge (on the hot gas line for the same installation) was pinned at maximum pressure. Both pressure gauges had a range of 0 to 150psi and were installed in a system with an operating pressure of 150 to 160psi. The pressure gauge failed from over-pressure operation.

Source: British Columbia Safety Authority

ARE YOU INPECTING SMALL BORE TUBING?

 An ammonia leak occurred at a commercial-industrial facility. Approximately 10 lbs ammonia entrained in approximately 200 litres of compressor oil was released when a suction side 3/8-inch pressure sensing line failed. The suction side oil pressure pushed approximately 200 litres of oil from the reservoir onto the floor where the entrained ammonia then escaped to atmosphere. The 3/8-inch stainless steel tubing within the compression fitting failed when a circumferential crack completely fractured. The crack within the
3/8-inch stainless steel compression fitting did not show up on external inspection. Metal fatigue appeared to be a factor, along with unit vibration and initial metal stress within this type of compression joint.
 

The refrigeration contractor identified the main cause and factors leading to the failure as a severe vibration condition of the compressor. This severe vibration condition only occurs when only happens when the control slide valve is at, or at near its minimum position. The vibration was so intense that the contractor immediately shut the compressor down. Also, the contractor’s investigation discovered the ‘PHD’ vibration monitoring system was inactive. When the monitoring system was activated, the compressor in fact shut down on ‘high vibration.’ 

Source: British Columbia Safety Authority

ARE YOUR SAFETY DEVICES WORKING?

Ammonia was released at a recreational facility. A high pressure cut out switch failed to shut down a compressor when the compressor experienced a high pressure condition. Pressure continued to build until a safety relief device operated releasing ammonia gas to atmosphere via the relief stack,
which triggered the ammonia alarm.
The water supply line to the condenser had no protection and was subject to freezing during cold weather. The high limit switch was old (1986) and is mounted on the compressor base subjecting it to vibration. The safety relief operated as designed, venting gas to atmosphere, preventing a possible
catastrophic failure.
Source: British Columbia Safety Authority

SAFETY IN DESIGN OF PIPING

 https://www.hydrocarbonprocessing.com/magazine/2018/february-2018/environment-and-safety/safety-in-design-during-piping-engineering

 "A process engineer must complete the preliminary preparations of process flow diagrams, material and energy balances, piping and instrumentation diagrams (P&IDs), process control philosophy, and identification of the hazardous nature of raw materials, chemicals, byproducts and final products. Afterward, documents including process equipment layout drawings (plan and elevation) and unit plot plans are issued to engineers from other disciplines.

Involving engineers from different disciplines in the design phase provides unique perspectives that add value to basic documents, such as improved safety design features. Discipline engineers are required to consider design and safety requirements that are applicable for their specific domain as per local, national, international, industry-specific and company standards and regulations, and good engineering practices.

The role of a piping engineer during the design of piping systems is explored here, as well as how that piping engineer can—from the initial design phase—lower the risks that can arise from handling hazardous materials, contribute to reducing potential liability and help create a safer environment for the public".

READ THE FULL ARTICLE IN LINK

 

CONTROL HAZARDOUS ENERGY

 https://www.aiche.org/ccps/control-hazardous-energy-lock-out-and-tag-out

"Lock-out and tag-out (LOTO) is a critical part of a strong all-around safety program. In LOTO, maintenance employees work with production employees to positively prevent all forms of hazardous energy from causing harm. Hazardous energy comes in many forms. Electrical energy can cause electrocution and burns, provide ignition to flammable atmospheres, and activate mechanical equipment. Steam can cause burns or initiate hazardous reactions. Nitrogen can cause asphyxiation. Chemical flow can cause uncontrolled reaction and injury. When a piece of equipment is being worked on, all sources of hazardous energy must be securely and positively locked out until the equipment is operational. Untold numbers of major process safety incidents and individual injuries have been caused by failure of LOTO. A prime example is the Bhopal catastrophe, one of the worst incidents ever to have occurred, which was caused in part by the failure of LOTO. Recently, a company process safety manager called CCPS asking for help in persuading a newly acquired facility within his company to implement a LOTO program. The manager was frustrated because, as the plant director stated, “We understand completely that maintenance workers are endangered if power or material flow were allowed to equipment they are servicing. That’s why no one would ever activate a switch or valve during a maintenance activity. LOTO is just extra, unnecessary work.” The company process safety manager knew that with the plant director’s attitude, the plant could be on the road to disaster. Could CCPS help him make the case for LOTO? At CCPS, we firmly believe that it is better to learn from the mistakes of others rather than to learn by painful, personal experience. So we asked CCPS member companies to give us examples of accidents caused by LOTO failures, and to provide testimonials about the importance of LOTO. The purpose of this article is to share this information with you, to help you lead the implementation or improvement of LOTO in your
company. A brief overview of LOTO procedures and tools are provided, as are references to more detailed resources." 

Reference: https://www.aiche.org/ccps/control-hazardous-energy-lock-out-and-tag-out

WHAT IS A BLEVE?

  http://www.hrdp-idrm.in/e5783/e17327/e27015/e27750/

For a BLEVE situation following four conditions must be present:-

1. There must be a substance in liquid form. Most of the destructive BELEV's that have occurred have involved flammable liquids and liquefied flammable gases. BLEVE can occur with any liquid, even water. The only difference is that with non¬flammable liquids there is no fireball. However, there will still be damaging effect including the propagating of creaks in the structure of the container together with possibility of subsequent failure and propulsion.
2. The liquid must be in a container like sphere, bullet, and road/rail tanker.
3. The contained liquid must be at a temperature above its normal boiling point at atmospheric pressure at the time container allows the pressure inside to build up above atmospheric pressure, the fluid, in the container is able to remain in the liquid state, even through its temperature is above its normal boiling point. This increase in pressure raises the Boiling point of the contained liquid above its boiling point.
4. There must be a failure of the container in order to have BLEVE. This container failure can be due to following courses:

• Flame impingement.
• Internal structural weakness of the container
• Failure of improperly designed SRV
• Impact from a mechanical cause such a road accident, tanker derailment allowing flammable liquid to flow out.

 

Lessons Learned: Pressure Vessels

SAFE ACCESSING OF PRESSURE VESSELS

 https://www.kan.de/en/publications/kanbrief/industry-40-vision-or-reality/safe-accessing-of-pressure-vessels

"Operatives and technicians must frequently climb into pressure vessels in order to perform construction, maintenance, repair and inspection work. However, the access points through which they must pass for this purpose are often so small that although access is possible, rescuing these personnel in the event of an accident presents considerable difficulties. The Polytechnic University of Milan has conducted a number of studies into this issue in the course of two degree theses."

SEE THE LINK FOR FULL ARTICLE

NON METALLIC GASKETS - AVOIDING LEAKS AND BLOWOUTS

 https://www.plantengineering.com/articles/nonmetallic-gaskets-avoiding-leaks-and-blow-outs/

"The compressive stress on a gasket plays a larger role in its ability to maintain pressure than its tensile strength.
By Dave Burgess October 1, 1999

The compressive stress on a gasket plays a larger role in its ability to maintain pressure than its tensile strength. Why is this significant? It is the reason for many gasketed joint problems!

In a classic scenario, a joint is assembled without controlled bolt loads; that is, without known and controlled bolt torques. The joint withstands a hydro test at 1.5 or 2 times rated pressure, yet leaks or blows out after a period of service at pressures well below the test pressure.

Was this failure due to a loss of gasket tensile strength? Probably not. Gasket tensile strength alone cannot be counted on to hold system pressures. What very likely occurred was loss of compressive stress on the gasket."

READ THE COMPLETE ARTICLE IN THE LINK

ETHYLENE OXIDE RELEASE INCIDENT

 https://dnrec.alpha.delaware.gov/croda-questions-answers/

 "What happened at the Croda Atlas Point plant?

At 4:15 p.m., Sunday, November 25, 2018 ethylene oxide (EO) was accidentally released into the air from Croda’s ethylene oxide plant. Since EO is very soluble in water, Croda deployed its water deluge system to contain as much of the release as possible. Croda personnel also began transferring the EO from the leaking vessel in the processing equipment to a secure containment vessel. Local responders and DNREC Emergency Response arrived. Water suppression continued. With input from Croda personnel, responders determined that by opening two nitrogen valves in the processing equipment, the remaining EO from the leaking vessel could be transferred to the non-leaking vessel, stopping the release."

 READ THE LINK FOR COMPLETE DETAILS...