How can a chemical plant be safely overhauled?

Corrosive media overhaul：

Leaked corrosive liquids and gaseous media may cause varying degrees of damage to the workers' limbs, clothing, and tools, and pollute the environment.

1. Before overhauling operation, we must contact the process personnel to drain, reset and flush the corrosive liquid and gas medium, analyse and qualify, and apply for the Permit to Operate.

2. Operators should wear labour insurance products according to the requirements, and be familiar with the work content, especially the opinions signed by the relevant departments.

3. Low-lying places for overhauling, there shall be no accumulation of corrosive liquids in the site, in order to prevent slipping and injuries during the operation.

4. The working surface of corrosive liquid should be lower than the legs, otherwise, we should contact the relevant personnel to set up scaffolding to prevent the residual liquid from drenching the body, clothing, but not to the iron bucket and other temporary support.

5. When working, wear rubber gloves, protective masks, rubber shoes and other special labour protection products according to specific conditions.

6. When disassembling, the connecting surface can be rinsed with water to reduce the erosion of corrosive liquid and gas media.

7. The limbs, clothes and tools in contact with corrosive medium should be cleaned in time; if there is any discomfort, it should be treated in time.

8. After the completion of the operation, the work is done, the material is clean, do a good job of site cleanliness and hygiene.

Overhaul of rotating equipment：

When rotating equipment for maintenance, misoperation of electric and steam sources generates misrotation, which can endanger the lives and property safety of maintenance operators; when the equipment (or spare parts) is large (heavy), improper safety measures can lead to mechanical injuries.

1. Before overhauling operation, we must contact the process personnel to isolate the system effectively, drain, flush and reset the flammable and explosive, toxic and harmful media in the fire repair equipment and pipeline, analyse the situation reasonably, and apply for the ‘operation permit’.

2. When repairing electrified (steam) equipment, contact with the relevant personnel and team, cut off the source of electricity (steam), and hang a sign on the switch box ‘prohibit the closing of the gate, some people work’.

3. The person in charge of the operation project should implement the safety measures of the operation and apply for the operation permit and approval; for the operation with great danger, the person in charge of the safety of the operation area should carry out the safety assessment and formulate the safety operation plan together.

4. Operators should wear labour protection equipment according to the requirements; be familiar with the content of the work, especially the opinions signed by the relevant departments, and implement them carefully before and during the operation.

5. The dismantled parts and components should be placed in different areas and well protected, and the important parts or components should be guarded by special persons on duty.

6. In the use of wind, electric, hydraulic tools and other operations, in accordance with the ‘safe operation instructions’ standard operation, safe construction.

7. When the equipment (or spare parts) is large (heavy) and requires the co-operation of more than one type of work, the command must be unified and the order is forbidden.

8. Strengthen the management of oil substances, all waste oil should be poured into the recycling bucket.

9. After the completion of the operation, the work is finished, the material is clean and the site is clear, do a good job of cleaning and sanitation.

Overhaul at height：

The working position is higher than the normal working position, which makes it easy for people and objects to fall and create accidents.

1. The person in charge of the operation project shall arrange to apply for the relevant permits, which shall be graded and approved according to the height of the operation; the person in charge of the production department where the operation takes place shall sign the departmental opinion.

 2. The person in charge of the operation project shall check and implement whether the scaffolding (ladder, basket), safety belts, ropes and other appliances used for work at height are safe, and arrange for the guardian of the operation site; a cordon shall be set up when the work requires.

 3. Operators should wear labour protection equipment according to the requirements, and be familiar with the work content

 4. When working at height, do not work vertically above and below at the same time. In special circumstances when simultaneous vertical operation is necessary, it should be approved by the unit leader and a special protective shed should be set up or other isolation measures should be taken.

 5. Avoid working at heights at night. If the work must be carried out at night, it should be approved by the relevant departments, and the person in charge of the work should carry out risk assessment, formulate safety measures, and ensure sufficient lighting.

 6. In the event of severe weather conditions such as wind above grade 6, thunder and lightning, heavy rain, fog, etc., which affects the sense of sight and hearing, or when there is no guarantee for personal safety, work at height is not allowed.

 7. In the process of work at height:

 ◦ The full guardian should always liaise with the person working at height, and should not be engaged in other work, not to mention unauthorised absence;  

◦ When abnormal conditions occur in the production system, immediately notify the person working at height to stop the operation and evacuate the site;  

◦ When there is a significant change in the operating conditions or operating environment, the Work at Height Permit must be re-applied.   

Service a fire：

Heating, slag scattering, and sparking may cause burns, fires, and explosions, as well as arc radiation and electrocution, which are also hazardous to the human body.

1. Before overhauling operation, contact process personnel to isolate the system effectively, and drain, flush and replace the flammable and explosive medium in the ignition equipment and pipeline.

2. After qualified analysis, apply for permits, graded approval; sampling and analysis of qualified, no one may not change the state of the process; the process of ignition operations, such as interruption of more than half an hour must be re-sampled and analysed.

3. The permit is carried by the personnel of the fire operation. All operators must be clear about the content of the work, especially the opinions signed by the relevant departments.

4. Operators must wear labour protection equipment as required, and hold the appropriate qualification certificate; before welding and cutting operations, the surrounding combustible materials must be removed, set up a warning line, hanging obvious signs, and shall not expand the scope of the fire without authorisation.

5. The fire operation should have a guardian and fire extinguishers; when the operation is in progress, it is prohibited for unrelated personnel to enter the fire site. In Class A fire zone for moving operations, the project manager should notify the professional firefighters to the scene in advance to assist in the supervision according to the regulations.

6. When carrying out electric welding operation, check the joints and lines intact to prevent accidents caused by electric leakage.

7. gas welding operations, oxygen cylinders and acetylene cylinders should be maintained at a distance of more than 5m, 2 cylinders and fire point distance should be maintained at a distance of more than 10m, check the gas pipe intact.

8. When welding and cutting at high places, the fire catching basin should be placed to prevent sparks from falling; at the same time, all combustible materials should be removed from below, and the gutter, well, cable, etc. should be covered.

9. When the combustible gas is under pressure without replacement of fire, there should be an operation plan and safety measures should be implemented. At the same time, the pressure in the equipment shall not be less than 0.98kpa, shall not exceed 1.5691mpa, to ensure that no negative pressure is formed; the oxygen content in the equipment shall not exceed 0.5%. Otherwise, shall not carry out the fire operation.

10. When the operators leave the fire site, they should cut off the power supply for construction and extinguish the fire source left behind in a timely manner, without leaving any hidden danger.

11. After the operation is completed, the work is finished, the material is clean and the site is clear, do a good job of cleaning and sanitation.

Confined space inspection：

There are hidden dangers such as lack of oxygen, high temperature, poisonous and harmful, flammable and explosive gases in the confined space, and if safety measures are not in place, it is easy for combustion and explosion to occur, which can cause accidents such as death and injury.

1. Contact craftsmen to cut off the power supply on the equipment connected with the outside world, and take locking measures, and add warning signs; effectively isolate all equipment and pipelines connected with the confined space or container.

2. After the confined space is discharged, isolated (plus blind), cleaned, replaced, ventilated, sampled and analysed, the operator will apply for permits and graded approval.

After sampling and analysis, no one shall change the process status.

3. Before operation, prepare emergency rescue materials, including safety belts, safety ropes, long pipe masks, safe voltage lighting not exceeding 24V, anti-electrocution (leakage) protectors and equipped with communication tools.

4. The supervisors should wear labour protection equipment according to the requirements and choose the position of the safety supervisors; during the process of supervision, they should contact with each other frequently, and when they find any abnormality, they should notify the operators immediately to interrupt the operation and evacuate from the dangerous area; at the same time, they must pay attention to their own protection.

5. Operators should wear labour protection equipment according to the requirements.

The first time they enter the confined space, they must wear a good gas mask (long tube or air respirator), and they must wear a safety belt and a safety rope; they should be familiar with the content of the work, especially the opinions signed by the relevant departments; the operators of the confined space should implement the shift system, change the shifts in time, and withdraw to the outside in time to take a rest.

6. After removing the cover from the confined space, barricades, fences and lighting must be set up to avoid accidents.

7. Entering the confined space operation must be analysed online, and if there is any abnormal situation, it should be evacuated in time.

8. After the operation is completed, the work is finished, the material is clean and the site is clear, do a good job of cleaning and sanitation.

Electrical overhaul：

During electrical maintenance work, electric shock hazards, arc hazards, or accidents caused by sparks from short-circuited wiring may occur, resulting in injuries to the human body such as electric shocks, arc-induced burns, and arc-induced blast injuries.

In addition, electrical accidents can cause fires, explosions, and power outages.

1. Before overhauling, contact the operator to cut off the power supply connected to the equipment and take locking measures, and hang a conspicuous signboard of ‘No closing, someone is working’ on the switch box or the main gate.

2. All the work on or near the electrified equipment needs to apply for a licence.

3. Workers should wear labour protection equipment according to the requirements (in line with the ‘substation work personal protective equipment requirements’), familiar with the content of the work, in particular, signed by the operator's opinion.

4. Electrical work can only be completed by qualified personnel, the work must be carried out by more than two people, one of them to monitor.

5. The electrical monitoring personnel must be professionally trained, obtain the certificate of competence, and be qualified to cut off the power supply of the equipment and activate the alarm signal; to prevent unrelated personnel from entering the hazardous area during the operation; and not to carry out other work tasks.

6. In maintenance and troubleshooting, no one shall change or adjust the setting value of the protection and automatic devices without authorisation.

7. Arc hazard analysis and prevention, for energy greater than 5.016J/m2 of the equipment, the arc hazard analysis must be carried out to ensure safe and effective work.

8. For the maintenance of processes or systems that are prone to static electricity, static electricity hazard analysis should be carried out and appropriate measures and procedures should be developed to prevent static electricity hazards.

9. Metal ladders, chairs, stools, etc. cannot be used in electrical work situations.