What is H2S?
H2S or hydrogen sulfide is one of the deadliest gases of the petrochemical industry and poses serious hazards to life and health if we avoid certain precautionary measures.
While working on the equipment which contains this, it is a colorless and highly flammable gas having a pungent odor, smells like a rotten egg and most widely found in fossil fuels.
How is Hydrogen Sulfide Formed?
- It generates as a by-product during the production and processing of petroleum products.
- In several cases, It forms during sewage and waste-water treatment, metal refining and pulp and paper production.
What are the Properties of H2S?
- Hydrogen sulfide is highly toxic in nature.
- It is a colorless gas.
- Hydrogen sulfide is soluble in water
- It is heavier than air
- H2S is a flammable & explosive gas.
- H2S is corrosive in nature
- Its odor is not a reliable warning of its presence.
- When H2S burns it produces sulfur dioxide (SO2).
- Its corrosive nature is the most important factor in the formation of pyrophoric materials.
What are the Effects of H2S due to its Exposure?
- At 1 ppm a sense of smell remains unchanged and a rotten egg odor is observed.
- At 10ppm an eye irritation is observed in some cases and it is the greatest concentration to work without respiratory protection for a normal 8 hrs.’ shift and is called a threshold hold limit value (TLV).
- There are several signs which have been observed at 100ppm like headache, cough and nausea, soreness of eye and sense of smell remains unchanged for 3 to 15 minutes.
- At 500ppm there is breathing difficulty, numbness in extremities, breakdown of the nervous system, convulsion.
- There are seizures, unconsciousness, failure of the respiratory organs, seizures, changes in the bowel movements and it can lead to fatality within 30 minutes at 700 ppm.
- Fatality in a few seconds and immediate unconsciousness is observed at 1000ppm.
How to Control the Hazard of Hydrogen Sulfide?
Now the point is how we can control Hydrogen sulfide, we can control it by several methods see the points below.
Work Permit:
The workforce needs to get permission to work from the client and area owner of the plant if the workforce is going to work in the field or on the equipment.
Flush and Purge with Nitrogen:
The equipment needs to be flush-off with water and purged with nitrogen prior to the start of the work.
Engineering Control Methods:
One form of engineering control is the installation of a local exhaust ventilation system on the equipment vent points.
Early Detection:
There must be arrangements for the early detection of H2S by calibrated gas monitor and placement of the portable monitors near the entry point.
Wear Appropriate Respiratory Protection:
One needs to make it mandatory for the entire workforce to wear appropriate and approved respiratory protection in the H2S area as per the standards to prevent them from imminent dangers of H2S.
Monitoring Air Quality:
You need to install air monitoring devices in the area to check the quality of air.
Installation of Windsocks:
There must be an identification of wind direction in the form of windsocks and wind flags so that the workforce must know where they need to traverse when emergency alarm bells.
Flare Lines:
If in case windsock and flag are not present the workforce needs to move in a crosswind direction after watching the flare lines of the plant in the brownfield.
Conduct Effective Training:
You need to provide training for all the workforce who are going to work in the area prior to the start of the work.
Training of the Workforce:
- Provide training to the workforce in such a manner so that they can recognize the emergency alarm of H2S when it bells.
- The entire workforce should know the ERP (emergency response plan) of the area.
- If it is feasible the companies need to work in such a manner to develop a plan which can give identification signal in the form of warning lights when there is H2S release.
- The crafts must have a generalized idea about the emergency exit points and muster points.
- Muster point is an area where the entire workforce of a particular area gathers when there is H2S release.
- Switch off all the types of equipment that run on electricity before moving to the muster point and you need to validate permits prior to the start of the work by the area owner.
- Inform the workforce in advance that they need to traverse in a crosswind direction when emergency alarm bells.
- Provide them with training on how to use emergency escape equipment in case of any disaster.
- The entire workforce must get training on how to use the emergency numbers displayed.
- As we know, it is a highly flammable gas so posters and flyers of no smoking need install in the areas as an awareness for the workforce.
Safe Design of the Process Equipment:
Design the equipment in such a manner that it contains a maximum number of vent points without disturbing the technicalities of the equipment.
Maintenance of the Equipment:
Maintain the equipment in a proper manner to avoid accidental release of H2S.
Proper Ventilation:
Install ventilation equipment on the vent points in order to generate an adequate flow of air as per the norms to avoid any imminent danger to the workforce.
Control the Leaks
In order to avoid leaks the bolts, nuts and gaskets must match the quality standards and proper specification and you need tighten and install it as per proper standard values.
H2S Detection is Very important:
The area that has the concentration of Hydrogen sulfide in that area you need to install fixed gas monitors and portable gas monitors in order to protect the workforce.
What is Hydrogen Sulfide Hazard Control in Critical Cases?
We know that we cannot purge and flush each and every piece of equipment, as there is certain equipment that comes on a critical path, where the workforce needs to work, so provisions and safety equipment must be made in the form of self-contained breathing apparatus (SCBA), supplied-air breathing Apparatus (SABA) and emergency escape cylinder for the crafts to prevent them from the dangers of H2S.
What are the First Aid Measures from Hydrogen Sulfide?
- If a person comes in contact with Hydrogen sulfide which is above TLV you need to move them to the fresh air location if you have proper training for the same.
- Don’t try to give them first aid if you are not having training.
- Don’t ever give the victim water because it can be disastrous and lead to fatality because when Hydrogen sulfide comes in contact with water forms acid.
- Get in touch with the Registered Govt. Medical practitioner immediately if things are not in control.
How do you Need to Store Hydrogen Sulfide?
- Hydrogen sulfide is a very dangerous gas and is highly flammable hence you need to store it in the cool shaded area away from direct sunlight.
- Follow HAZCOM procedure during handling and transportation.
FAQ
Ans: -Hydrogen Sulfide can be tested by performing gas test by an Authorized gas tester.
Ans: -You cannot achieve 100 % perfection in this but you can clean the vessel, flush it water and purge it with Nitrogen.
Ans: -The victim must be moved to the fresh area under Medical Supervision
Ans: -Perform Gast test and ensure that there is no hydrogen sulfide in the said equipment before allowing a person for work.
Ans: -Normally it smells like a rotten egg but is strongly advised and recommended not to rely on your sense of smell and perform gas test prior to man entry.
Final Thoughts
Last but not least, always follow the safety protocols of the company as well as the client in order to save yourself from the imminent dangers of H2S.
As a good employee, save the company from fines by enforcement agencies and when you work in such environments be careful and think before any action and maintain a healthy life.