A few things you must know about pipe network operation and maintenance safety
Release Date: 2018-07-02
The so-called limited space refers to the space that is closed or partially closed, relatively isolated from the outside, and the entrance is relatively narrow. Operators cannot work for long periods of time. Natural ventilation is poor, which is likely to cause toxic and harmful, flammable and explosive substances to accumulate or insufficient oxygen content. .
Limited space must meet the following three conditions at the same time.
1. The volume is large enough for people to fully enter;
2.Limited or restricted import and export;
3. Not designed to take up space for a long time.
The main features of limited space:
(1) Poor ventilation can easily cause toxic, flammable and explosive accumulation and lack of oxygen; this feature is the main cause of fatal accidents in limited space, and hydrogen sulfide is common in toxic and harmful gases; First, there must be sufficient harmless air in the space.
(2) For some limited spaces, the complexity of the internal structure is also one of the causes of the accident.
The air generally contains 21% oxygen. Oxygen may be reduced in the following cases, threatening life:
| Oxidation reaction
火工序、发酵、发霉。 Oxygen is consumed by gasification, such as welding, gas welding cutting, rusting, open flame processes, fermentation, mold.
| 2. Replace
Oxygen is squeezed out by inert gases such as nitrogen, argon, carbon dioxide.
| 3. Surface absorption
Oxygen is adsorbed by porous surfaces, such as activated carbon.
The oxygen content in the breathing air causes adverse physiological reactions to the human body:
2. Flammable space
限空间有易燃气体可引起爆炸及火灾，易燃性空间是由空气中的氧气与易燃性的气体、蒸气或粉尘混合而成。 Flammable gas in a limited space can cause an explosion and fire. A flammable space is a mixture of oxygen in the air and a flammable gas, vapor or dust. These gases and vapors may be formed from residues containing flammable materials, or from the use of flammable materials, or from chemical processes such as the production of biogas.
Flammable dust fills the space or is disturbed and flies, it also forms flammable material space. Dust can come from crops such as flour, chemicals, plastic pellets, drugs, or metal powders.
When flammable spaces encounter fires such as welding sparks and sparks from handheld appliances, they can cause an explosion.
3. Hazardous substances
The main routes of exposure to hazardous substances are through breathing, skin absorption, and eating. The health effects of exposure to a hazardous substance can be chronic or acute, depending on the time of exposure, the concentration of the exposure, and the health effects of the substance, such as corrosive, toxic or harmful.
Some toxic gases have a unique odor. For example, hydrogen sulfide smells like rotten eggs. However, some toxic gases cannot be detected by the nose, such as colorless and odorless carbon monoxide. In addition, odorous toxic gases such as hydrogen sulfide are likely to be anesthetized after a short period of contact, and they can no longer be detected. Therefore, only instrumental measurements are reliable.
4. Physical hazard
| Mechanical hazard
Hazardous parts such as belts, shafts and gears may be injured when touching various equipment.
| 2. Electrical hazards
It is easy to encounter electrical hazards when contacting cables, wires, transformers in confined spaces, and using appliances in humid spaces, and there is a danger of electric shock, burns, and electrical shock.
| 3. Harm of noise
Noise from working in confined spaces will be higher than normal, causing employees with hearing impairment or hearing loss.
| 4. Radioactive Hazard
Use radioactive equipment such as lasers and light from welding in confined spaces.
| 5. Environmental hazards
Common factors that can cause danger in confined spaces:
Too hot or too cold
| 6. Harm of traffic
some 限空间的进出点位于行人道或马路时如排水道，工作人员会有被车撞到的可能， 其他人也会有跌下受限空间的危险。 When the access point of the limited space is on the sidewalk or the road, such as a drainage channel, the staff may be hit by the car, and others may fall into the restricted space.
| 7. Engulfed by liquid or flowing solids
限空间如有积水或有水或其他液体突然涌入，便有被淹溺的危险。 There is a danger of being drowned if there is stagnant water or a sudden influx of water or other liquid into a confined space. In addition, flowing solids such as sand, grain, etc. can also pose a risk of engulfment.
5. Other hazards
1.体力操作的危害 | 1. Hazards of manual operation
限空间内的工作环境一般都陕窄且须要大量体力操作。 The working environment in a limited space is generally narrow and requires a lot of manual operation. The use of personal protective equipment can increase the difficulty of manual operation.
| 2. Biological hazards
Working in confined spaces can be infected with various types of bacteria, viruses, and even biological hazards caused by insects and snakes.
A risk assessment is a process used to identify hazardous risks. The employer should conduct a risk assessment for each identified hazard, including considering the opportunity for any operator to be exposed to the hazard, the extent of the impact, and the effectiveness of existing risk control measures.
The person conducting the risk assessment should decide which assessment method to use and what should be done 限空间作实地视察。 Site visits in limited space.
The main considerations of a risk assessment should include:
是每次进入密闭空间前必须进行的程序，而该证只对一个密封空间工作有效。 A work permit is a procedure that must be performed before each entry into a confined space, and the permit is valid for only one enclosed space. Any operator entering a confined space must apply for a work permit from the person in charge authorized to issue it.
The permit must specify the tools and construction requirements that are allowed and not allowed. Before issuing a work permit, the person in charge must ensure that the air at the work site is at a safe level, and that it is normal during construction and is not dangerous; other risk control measures have also been effectively completed.
When the completion time stipulated in the permit is reached, the confined space must be left. If it is necessary to work for an extended period of time, a work permit must be applied for separately.
The work permit and risk assessment report must be posted in a conspicuous place near the confined space for staff to refer to.
Personal protective equipment is the last line of defense, ancillary measures, or temporary measures to control hazards, but it is by no means the only measure. In order to bring out the function of personal protective equipment, we must first pay attention to whether they can meet the working requirements, meet the standards, match the body type, be easy to use, and have regular maintenance and replacement arrangements.
Protect your head from falling objects or pendulum animals.
| Eye mask, face mask
Protect your eyes from strong light or flying objects.
| Earbuds, headphones
Protect hearing from high noise doses.
| safety shoes
Protect your feet from bumps and stabs, and prevent slipping.
| seat belt
Sling-type safety belt prevents workers from being injured by falling
Protect the respiratory system from toxic gases, smoke, mist and dust. Mask type respirator can isolate smoke and dust, filter type can absorb chemical vapor, and air supply type can provide life-sustaining air in poisonous or lack of gas environment.
Should be based on 限空间作业的特点，制定应急方案。 Characteristics of confined space operations and formulate emergency plans. Contingency plans include: risk analysis, preventive early warning, emergency response, emergency response, rescue methods, on-site monitoring, and post-disposal. And carry out emergency drills, records and archives. 应急器具包括有： Common emergency devices include:
Identify and apply for entry 限空间许可证的决策流程 Decision-making process for limited space permits