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