HAS YOUR HAZOP STUDIED THIS POSSIBILITY?

 On April 2, 2003, Employee #1 and a coworker, the technicians, were watching a polymerization process involving styrene and acrylonitrile monomers. Employee #1 and the coworker's jobs involved monitoring a reactor vessel throughout the process. At the end of the batch process, non-polymerized monomer and vapors were stripped from the reactor through a condenser system to a distillate collection tank and were ultimately charged to subsequent batches. Toward the end of the stripping process, Employee #1 left the control room to determine if enough distillate had been removed to allow the remaining water and mixture to be dumped to the "dirty" sewer and a collection system. While Employee #1 was in the vicinity of the reactor, an explosion occurred in a small auxiliary charge tank. A piece of metal struck Employee #1's abdomen and killed him. Although the charge tank was not in use at the time of the accident, a small amount of the batch had back-flowed through a valve between the reactor and the auxiliary tank during the reactive process. The batch continued to react in the auxiliary tank, overheating and overpressurizing the tank. 

Source:Osha.gov

WHERE DO YOUR RUPTURE DISCS VENT?

 Employee #4 was cleaning the #6 chemical reactor on July 19, 1990, with a flammable mixture of solvents when the reactor burst its rupture disc and the mixture was expelled into the plant. The solvent ignited and the vapor cloud explosion resulted in the plant's 43 employees being injured by flying debris and/or being thrown by the force of the explosion. Employee #4 eventually died from his burns. Employee #1, a maintenance employee, was moving away from the area when he was struck in the head and killed by debris flung during the explosion. 

Employees #3, #6, #7, #8, #9, #16, and #19 were located in the manufacturing offices in Building 4, about 75 ft south of the reactor. Employees #2, #10, #11, #12, #14, #15, and #17 all worked in Building G, 50 to 75 ft southwest of the reactor and were leaving when the explosion either threw debris at them or threw their bodies onto equipment or debris. Employee #5 was in the same building as the reactor and was thrown down by the explosion, sustaining burns and crushing injuries. Employee #13 sprained his knee while moving from the break room to the courtyard, about 100 ft southeast of the reactor. Employee #18 suffered a sprained left thigh and a bruised shoulder. 

It appeared that the reactor was not vented to a safe location and had primitive temperature controls, and the company did not enforce the mandatory attendance of operators at the reactors during operation. All of these factors, including minimal operating procedures (none specifically for cleaning), led to the explosion and the resulting extensive injuries and property damage. 

Source:Osha.gov

Electrical Protection of 3 phase Motors: Types and Protection Schemes

Electrical Protection of 3 phase Motors: Types and Protection Schemes: Motor thermal protection, motor protection setting, motor protection breaker, Thermal Protection, TP designation for electric motors, IEC 60034-11

Process Control Basics

Process Control Basics: We Provide Tools and Basic Information for Learning Process Instrumentation Electrical and Control Engineering.

CAMPAIGN AGAINST ASPHYXIATION

 https://www.linde-gas.com/en/images/Campaign%20against%20asphyxiation_tcm17-13907.pdf 

Share this newsletter with all your employees and contractors. It may save a life.

COLD BURN INCIDENT

On Tuesday 17th May, a worker received serious cryogenic burns after immersing their hands in a container of liquid nitrogen whilst trying to shrink a brass bush for inserting into an excavator boom arm.

How did it happen? 

The worker was not wearing the correct personal protective equipment for the task. Further details related to the incident are not available at this time 

Key issues

Liquid Nitrogen

Liquid nitrogen is one of the cryogenic liquids commonly used in the mining industry. As “cryogenic” means related to very low temperature, it is an extremely cold material. Liquid nitrogen has a boiling point of negative – 195.8 degrees centigrade and can expand to a very large volume of gas.

The vapor of liquid nitrogen can rapidly freeze skin tissue and eye fluid, resulting in cold burns, frostbite, and permanent hand and eye damage, even by brief exposure.

Liquid nitrogen expands 695 times in volume when it vaporises and has no warning properties such as odour or colour. Hence, if sufficient liquid nitrogen is vaporised to reduce the oxygen percentage to below 19.5%, there is a risk of oxygen deficiency which may cause unconsciousness. Death may result if oxygen deficiency is extreme. To prevent asphyxiation hazards, handlers must make sure that the work area is well ventilated.

Without adequate venting or pressure-relief devices on the containers, enormous pressures can build upon evaporation. Users must make sure that liquid nitrogen is never contained in a closed system. Use a pressure relief vessel or a venting lid to protect against pressure build-up.

Handling Safety Practices

Liquid nitrogen should be handled in well-ventilated areas.
Handle the liquid slowly to minimize boiling and splashing.
Use tongs to withdraw objects immersed in liquid nitrogen - Boiling and splashing always occur when charging or filling a warm container with liquid nitrogen or when inserting objects into the liquid.
Use only approved containers. Impact resistant containers that can withstand the extremely low temperatures should be used. Materials such as carbon steel, plastic and rubber become brittle at these temperatures.
Only store liquid nitrogen in containers with loose fitting lids (Never seal liquid nitrogen in a container). A tightly sealed container will build up pressure as the liquid boils and may explode after a short time.
Never touch non-insulated vessels containing liquid nitrogen. Flesh will stick to extremely cold materials. Even non-metallic materials are dangerous to touch at low temperatures.
Never tamper or modify safety devices such as the cylinder valve or regulator of the tank.
Liquid nitrogen should only be stored in well-ventilated areas (do not store in a confined space).
Do not store liquid nitrogen for long periods in an uncovered container.
Cylinders should not be filled to more than 80% of capacity, since expansion of gases during warming may cause excessive pressure build-up.

Eye / Face ProtectionSuitably rated full face shield over safety glasses or chemical splash goggles are recommended during transfer and handling of liquid nitrogen to minimise injuries associated with splash or explosion.

Skin Protection

Suitably rated, loose-fitting thermal insulated or leather gloves, aprons, long sleeve shirts, and trousers without cuffs should be worn while handling liquid nitrogen. Safety shoes are also recommended while handling containers. Gloves should be loose-fitting, so they are able to be quickly removed if liquid nitrogen is spilled on them. Insulated gloves are not made to permit the hands to be put into liquid nitrogen. They typically only provide short-term protection from accidental contact with the liquid.

Source: https://www.rshq.qld.gov.au/safety-notices/mines/use-of-liquid-nitrogen-in-the-mining-industry

NITROGEN ASPHYXIATION INCIDENT

At approximately 2 a.m. on August 8, 2001, Employee #1 was working on top of a reactor under nitrogen purge. A coworker was wearing breathing air with a communication device. The lead man was on top of the reactor overseeing the job. The lead man turned around and began communicating on the headset with the workers monitoring the breathing air. Employee #1 walked past the lead man and the coworker without breathing air and reached into a manhole. Employee #1 was overcome by the fumes/vapors and fell 3 to 4 feet into the reactor. The coworker and lead man pulled Employee #1 out of the reactor, and the lead man performed CPR until the rescue team arrived. Employee #1 was pronounced dead at the hospital. Employee #1 died from asphyxiation. 

Source:Osha.gov

PIGGING INCIDENT

At approximately 8:00 a.m. on June 25, 2012, an employee was at the side of the pig launcher. The process was to purge the line of carbon gas with nitrogen. The nitrogen was pumped by a rig used to frac wells. The pump truck was capable of creating pressures which were several times greater than the launcher was designed and built for. 

The employee had several responsibilities some of which were to check the joints of black pipe feeding the nitrogen. This entailed pouring soap water on the joints and check for bubbles. He was also responsible for watching the pressure gauges on the launcher, getting the line purged so the pigging operation could start, and opening and closing the ball valves in the line t o provide for proper flow. He had just spoken to another employee while looking at the gauges on the launcher when the launcher ruptured. The ball valve leading to the 16-in. main line was not open. The pump truck had been pushing nitrogen into the small pig launcher instead of over three mile long pipeline. The gauges were not reading any pressure at all and when the pump truck kicked up the pressure, the launcher ruptured. The launcher was shot over 800 feet away. 

The main part of the vessel struck another employee killing him instantly. 

Source:Osha.gov