Continual Improvement Process (CIP)

A continual improvement Process (CIP) is an important concept used in Environmental Management Systems as well as in Safety /Risk Management Systems. 

The term “Continual” is slightly different from the term “continuous”. The latter is referred to something happening continuously, while the former is used to identify a process happening with “quantum steps” but move forward with the time.

It is extensively important that a CIP  related to the overall safety/risk management system is running during the life time of a plant. A plant is changing all the time due to modifications, changing process/operating conditions, and aging equipment, etc. So the Safety management system should be able to adapt to these changes and simultaneously improve it with the latest technology, guidelines, and case study experience. An ALARP (as low as reasonably practicable) process can be used to assess suitable CIP steps during risk management.

Containment failure of hazardous liquid chemicals

A couple of months ago, West Virginia (US) was in a state of emergency due to the leak of 4-methylcyclohexane methanol into river Elk, just about a mile upstream from a water treatment plant intake. It has been understood that domestic water supplies were contaminated by an unknown amount of the chemical.

4-methylcyclohexane methanol is used (as the major compound) in Froth-floatation processes for cleaning coal (to remove impurities from freshly mined coal).

We take this time to remind you of a few key safety aspects related to the containment of dangerous, toxic, or generally hazardous liquid chemicals in bulk quantities.

1. Assess the inherent risks of hazardous chemical storage tanks.
2. Assess the risks posed by the stored maximum quantities.
3. Get to know the maximum allowable storage quantities and other regulations stipulated by the relevant authorities.
4. Ensure that all employees, especially those who are working closely with the process system and the tanks, are aware of the danger posed by the spill of the chemical by containment failure.
5. Make sure that the storage tanks delivered by the suppliers are made according to the necessary engineering standards.
6. Take all necessary safety precautions (including engineering control, and safety functions) to avoid overfilling of tanks.
7. Perform regular visual inspection of tanks for small leaks, corrosion, cracks, bends, other anomalies on the surface, or other structural damages, blocked vents, etc.
8. If visual inspections are leading to suspicious conditions, take the tank out of the process stream immediately and empty the content. Call for a qualified inspection agency to carry out a full and detailed inspection of the tank.
9. Perform detailed tank inspections at predetermined regular intervals.
10. Strongly follow up actions on any recognized weaknesses or problems during such inspections.
11. CONSTRUCT A SECONDARY CONTAINMENT. During the latest West Virginia incident, it is being told that the capacity of the secondary containment has been exceeded by the leak and then the chemical has flowed out of the secondary containment too. THE SIZE OF THE SECONDARY CONTAINMENT MUST BE DECIDED BY A RISK ASESSEMENT JUDGING THE MAXIMUM EXPECTED LEAK RATE.
12. Prepare an emergency response plan for the worst case scenario, i.e. usually the rupture of the whole tank (or a combination of several tanks, if it is likely). Update the emergency response plan on a regular basis.

Depressurization and Blowdown

In the event of a process plant fire, or an impending fire /explosion /collision or any such threat, it is absolutely necessary that any gaseous or liquid hydrocarbons contained in pipelines or vessels to be transported out of the endangered area. This is intended for following reasons,

- To avoid vessel and pipeline rupture caused by heat weakening of the containment materials
- Rupturing vessels and pipelines generate projectile fragments which endanger people and also cause further damage to equipment and structure
- Combustibles containing in rupturing vessels and pipelines further fuels the initiated fire.
- Rupturing vessels may release toxic /harmful materials which endanger humans and the environment

If the involved hydrocarbon (or any such combustible /hazardous /or pressurized material) is gaseous, this removal process is called “depressurization”, and if the involved hydrocarbon (or any such combustible or hazardous material) is a liquid, then the removal process is called “Blowdown”. However it is noted that some people tend to use these two terms interchangeably (especially in Scandinavia).

Note that many process vessels have pressure safety valves (PSVs) which shall activate in the event of a high pressure development in the system. PSVs shall release pressurized material into a safer area if the predetermined pressure limits are exceeded.

But, in the event of a fire, PSVs can render useless due to the reason that a vessel can rupture at a pressure far below its PSV set point (and even under normal working pressure of the vessel) due to the reason that material strength of the vessel is severely reduce due to the heat exposure. That is why depressurization and blowdown (D&B) is very important irrespective of other pressure safety arrangements.

The depressurization and blowdown philosophy is a very important part of any Emergency Preparedness Plan related to a process facility that contains large quantities of combustibles or pressurized /hazardous materials. This plan should elaborate which areas /vessels to be depressurized in which sequence. Usually, a typical process plant’s depressurization and blowdown capacity is limited at a certain rate. Hence, the D&B process should be sequenced for different fire scenarios with mostly endangered areas are prioritized.

There are many considerations to be made when developing a Depressurization and Blowdown Philosophy. We will discuss some of these aspects during forthcoming posts.

A fire ball