How much do you know about nitrogen safety?
Nitrogen safety knowledge
- Nitrogen usage
At present, in our work site, nitrogen is used in many occasions: equipment purging, instrument power gas, drying and so on.
Consider: Where else would nitrogen be used? In particular: the use of open-mouth nitrogen?
- Properties of Nitrogen
The content in the atmosphere accounts for 78%; nitrogen is colorless, tasteless, odorless; cannot support life; inert gas.
- Nitrogen risk
Non-toxic: Nitrogen is 78% of the air we normally breathe, however, it kills you without warning and is seen as an "invisible" killer, causing suffocation if nitrogen replaces the oxygen content in the atmosphere we breathe , records indicate numerous nitrogen asphyxiation fatalities in refineries and chemical plants worldwide.
When a person enters an oxygen-deficient environment, the oxygen in the arteries drops to very low levels within 5-7 seconds. After 10-12 seconds, he begins to lose consciousness, and if he can't breathe oxygen within 2-4 minutes, he will suffer from heart failure and then die.
Removing an injured and unconscious person from nitrogen to fresh air does not fully promote recovery, and patients must also undergo physical therapy to restore oxygen to the brain.
- Accident cases
A process operator was suffocating by an open manhole under nitrogen purging while sampling (gas) from the reactor, and subsequently died. The body was found in the second layer of material tray 6 meters away from the manhole.
Special care is required when testing atmospheric oxygen levels in confined spaces.
The below are typical examples of bad habits.
In one incident, a subcontractor employee (not wearing breathing equipment or seat belts) entered the isolation area at the top of the reactor and attempted to help a caregiver entering the confined space out of the ladder inside. Unfortunately, he was conquered by the oxygen-deficient environment around the manhole, and the man fell directly into the reaction kettle. Without the oxygen necessary to sustain breathing, it is impossible for anyone to get out of the reactor alive!
- Safe Practices:
A specialized device is placed in manholes and other openings in confined spaces containing oxygen-deficient gas. The unit can be locked to prevent unauthorized removal and access to confined spaces. Demolition can only be done with a restricted space entry permit.
- Fatalities in Temporary Confined Spaces
It has been several weeks since the process tower was out of operation and moved into a maintenance phase. The tower has been purged, is being purged with nitrogen, and has several manholes open. Two experienced workers inspect the flange face of a remote manhole for stress cracks. They sprayed dye on the flanges and used a black light to verify suspected cracks. At this time, the sun is shining and the wind is blowing.
They put tarpaulin shields over the flanges, but I don't know if that's to keep out the wind when using tinted penetrants or to facilitate black light inspection. The enclosed space formed by the tarpaulin hood soon filled with nitrogen gas, and both suffocated and fainted. One died, the other narrowly survived because his face was turned toward the metal grille when he fainted, allowing him to inhale enough oxygen to stay alive.
The immediate cause of the accident was the inadvertent creation of an enclosed space environment around an open manhole that was being purged with nitrogen. The root cause is the failure to recognize the suffocation hazard of nitrogen gas coming out of confined spaces and manholes, and the lack of proper controls for working on a column that is being nitrogen purged.
- Gas monitoring
Using a portable detector, it will alarm when the oxygen concentration is in a critical state. Usually, the alarm level of the gas detector is 19.5% (low O2 alarm) and 23.5% (high O2 alarm). Before entering, first use a rope to send the monitor into the container to check the oxygen content. Do not enter the tank area and trench for oxygen content testing without wearing an air respirator. If the oxygen content is less than 19.5%, do not enter the confined space. If the content exceeds 21%, something must be wrong, such as an oxygen cylinder leak. This situation must first be investigated before personnel enter the confined space.) If there is a danger of oxygen deficiency in the atmosphere, then continuous ventilation is necessary !
- Safety measures to prevent suffocation
Vents and openings in inert gas-filled spaces are located as far away from personnel as possible, as far as is reasonable.
Air breathing apparatus must be worn when the presence of nitrogen around the work may cause hypoxia and you are at risk of exposure to nitrogen. List appropriate precautions and enforce them on the construction site. Personnel working near these vents and openings must be properly trained, competent and wear appropriate respirators.
When personnel are no longer in and the opening is left unattended, the opening must be covered, if practicable, fitted with an anti-tamper gas seal or bolted flange, care should be taken to depressurize the container or pipeline containing the inert gas, and No gas escapes from either open end during assembly.
Appropriate measures should be taken to keep persons in safe areas near areas containing inert gases and not wearing respirators. These must include enclosures, warning signs, notice boards, etc.!
Do not enter fenced areas
Set up warning systems, notices and containment in affected areas.
Safety signs, ropes, tapes or other fixed barriers should be placed on all passages leading to and at a distance from an area filled with inert gas, and ensure that the space is outside the barrier regardless of wind conditions and openings. No personnel will be affected by asphyxiation of the inert gas in use.