Turnaround (abbreviated as TAR, TA, or ATA) is a planned event wherein an entire process of a plant (refinery, petrochemical plant fertilizers plant, etc.) is taken off-stream for a long duration (more than a month) to perform equipment overhauling, cleaning, inspection, maintenance, replacement, modifications, piping work, etc. Turnarounds are non-routine, troublesome, complex, and potentially more hazardous than normal plant operations. The situation becomes more complex and hazardous when revamp of the unit is also involved along with turnaround. Moreover, a short shutdown for partial maintenance of equipment is also a big safety risk because some sections of the unit remain pressurized with process chemicals. Safety must be the top priority in every step of shutdown or turnaround otherwise accidents may happen.
Note: These are only general guidelines based on personal experience, please follow your own safety procedures and standards.
The key to a safe and successful turnaround is strict compliance with the Work Permit Systems.
These are selected turnaround safety topics and can be converted into turnaround safety presentations. Further, this can be a good material for turn-around safety toolbox talk. Mainly, these are written for oil refinery safety but can also be followed in the petrochemicals, chemicals, fertilizer processing plants, and for oil and gas to safely conduct the shutdowns. Although these turnaround safety guidelines are written for long shutdowns but are equally applicable for the short shutdown of the unit for partial maintenance and repair of equipment.
- 1 Safety Considerations During a Turnaround or Shutdown
- 2 7. High Wok Force in Turnaround
- 2.1 8. Hot Works Hazards and Control Measures
- 2.2 9. Safety Precautions for Couplings and Fittings
- 2.3 10. Flexible and Pressurized Hoses Safety
- 2.4 11. Catalyst Unloading and Loading Safety Hazards
- 2.5 12. Electrical hazards and Safety Measures
- 2.6 13. Work at Height
- 2.7 14. Pyrophoric Materials Safety
- 2.8 15. SIMOPS (Simultaneous Operations)
- 2.9 16. Confined Space
- 2.10 17. Poor House Keeping
- 2.11 18. Communication Hazards During Turnaround
- 2.12 19. Austenitic Stainless Steel Protection
- 2.13 20. Extensive Working Hours
Safety Considerations During a Turnaround or Shutdown
The following are some general safety rules for long or short shutdowns of process units for handover to maintenance handover.
1. Unit Shutdown for Maintenance Handover in Turnaround:
Unit shutdown requires close attention to the recovery of process fluids as maximum as possible to avoid their hazards during handover for maintenance. Following are health and safety precautions during the handover of the equipment for maintenance;
- First, transfer the process fluids to safe storage. Also, before shutdown ensure a minimum inventory of process fluids in the storage tanks.
- Try to focus on the handover hazards and controls as much as possible during the shutdown of the unit for TA. Prepare Standard Operating Procedures (SOPs) and risk assessments in advance while keeping in mind all the shutdown hazards.
2. Steam Out of Process Piping for Cleaning
Steam-out is a steam purging process to remove process fluids, toxic gases, chemicals, etc. to make them ready for personal entry or maintenance jobs. Steam is introduced into the column/vessel at the bottom and allowed to flow through to the top vent into the atmosphere, sweeping out hydrocarbons to the atmosphere. Gradually the vessel gets heated and the resulting condensate is drained at the bottom.
- Normally, the steam is injected from the vessels’ sides or bottom and is vented from top points. Also, low point drains are opened to remove the condensate from the system.
- First, check the steam pressure and temperatures. Also, check that the process piping and equipment are designed to withstand the steam conditions.
- Check that equipment is designed for vacuum. In case the vessel is not designed on vacuum then it may be damaged, created during condensate draining.
- To avoid a vacuum, all the vents should have been left open after steaming for condensate draining to break the vacuum. In addition, Nitrogen may be introduced into the system to make some pressure.
- Initially, steam-out vents and drains should be directed to flare or close the drain system to avoid exposure to toxic chemicals. If the system does not have a permanent close drain system then temporarily connect to the nearest point. After the hazardous chemicals are cleared, then open atmospheric vents and drains.
- At the start, the cold vessel may cause rapid condensation of the steam which may produce a water hammer. It can damage column internals and pipe fittings. So, introduce steam at low rates, drain the condensate then gradually increase the steam flow rate.
3. Water Flushing for Cleaning of Process Piping
Water flushing of process piping and equipment is carried out to remove, hydrocarbons, chemicals, or any other toxic material or cleaning of the process lines.
- Main hazards include high pressure of water, vacuum creation during drain out, and impurities ingress in the process systems from the water.
- Check the design pressure of the circuits to be flushed. Also, analyze water impurities before the activity.
4. Nitrogen Purging
Nitrogen purging meaning is to replace toxic & flammable materials with inert gas. Further, it also reduces the fire or explosion potential by removing the oxygen from the system. The two most common methods of purging are displacement and dilution. The process requirement determines which method to be used. It is better to perform a Nitrogen purging risk assessment and apply control measures accordingly. Further, develop procedures for Nitrogen purging of your specific process area.
- Nitrogen is non-flammable and weighs approximately the same as air. Nitrogen is a “silent killer’’ as it replaces oxygen and causes asphyxiation. Exposure to excessive amounts of Nitrogen enriched atmosphere may cause dizziness, drowsiness, nausea, vomiting, excess salivation, diminished mental alertness, loss of consciousness, and ultimately death.
- Where nitrogen is used, consider monitoring the oxygen concentration in the area to ensure it does not drop below safe levels.
- Don’t assume that oxygen concentration in a vessel or any other confined space is within acceptable limits. Always monitor it before working near the opening or inside any confined space.
- Another hazard is the pressure of Nitrogen (5~8 bar) which can cause personal injury if exposed to this high pressure.
5. Equipment Handover for Blinding and Maintenance
Before handing over, the processing system must be isolated, depressurized, drained, purged, flushed, and hydrocarbon or toxic gas-free, especially for hot jobs & confined space entry.
- Prepare the isolation plan of equipment or a part/section of the plant. Identify and highlight blinds drains or first break flanges on P&IDS (Piping and Instrumentation Diagrams).
- Major risks during isolation and blinding are exposure to toxic, hot, or pressurized process fluid. This can be very dangerous, depending on the nature of the fluid. So, depressurize, drain, flush or purge before handing over the equipment or piping.
- Initially, open from the smallest flange and then go for the main flange dismantling for blinding.
- The First Break is the act of breaking the integrity of process piping or equipment that might contain toxic and hazardous products. It is a potential planned loss of containment where there is potential for trapped pressure or exposure to a toxic material or a substance that has not yet determined to be toxic or non-toxic.
Normally, the first break is carried out after the equipment has been drained, depressurized and purged, or flushed. The first break is done by breaking a flange or opening a valve on a line that contains the potential for H2S, Benzene, or any other respirable harmful substances.
A vent or drain can be the first break on a system and if a vent or drain valve test has proven that the first break is free of hazardous pressure or fumes then any flange following the first break would be considered the second break and can be done with a proper job safety analysis. But a second break must be treated as a first break if there is an equal risk of exposure or trapped pressure potential.
- If still, there are chances of exposure then use proper PPES and dress to save the workers from the toxicity and high temperature of the fluid.
6. Chemical Cleaning
Chemical is the use of chemicals to dissolve, remove, or loosen deposits from process equipment and piping. Chemical cleaning is a process that primarily uses chemical solutions to remove fouling from inside plants and equipment. Process equipment heat exchangers, vessels, and piping circuits are chemically cleaned to resume their efficiency by removing scales or any other fouling materials. Chemical cleaning products that contain corrosive chemicals can cause severe burns if splashed on the skin or in the eyes. Chemicals that contain bleach and ammonia can cause severe lung damage or death.
- Do the risk assessment and identify all the chemical cleaning hazards.
- Prepare chemical cleaning procedures and anticipate all the hazards and their control measures.
- Strictly, follow all the instructions on the Safety Data Sheet (SDS) of a specific chemical.
- Ensure safe storage of the chemicals away from direct sunlight, heat, and food items.
- Label them properly to avoid their mistaken use for any other purpose.
- Encourage maintenance persons to seek medical advice if any irritation or an allergic reaction due to cleaning chemical develops.
- When diluting acid with water, always add the acid to the water, not the water to the acid.
- In addition, use a standardized and healthy fitting, piping, and pumping system to avoid spillage. It is better to test the circuit with water and rectify any leakages before starting with actual chemical usage.
- For further study see the links; OSHA Chemical Cleaning, Cleaning chemical safety information.
7. High Wok Force in Turnaround
In TA or shutdown, there might be two or three times a higher workforce than the normal worker traffic. Further, most of them are unfamiliar with the site and its potential hazards.
- Administrative controls must be applied to keep away the workers from potential plant hazards. Because some of the employees can be unfamiliar with the working environment.
- In addition, safety inductions must be properly implemented and all the coming workforce should be trained and made aware of all the site-specific dangers and safety rules.
8. Hot Works Hazards and Control Measures
Any work that has the potential to create a spark, heat, or hot slag which could ignite any combustible or flammable materials placed nearby. Examples of hot work include welding, cutting, grinding, brazing, soldering, thawing, operation of engines, generators, or any other tool which is not explosion-proof or intrinsically safe, exposing pyrophoric materials, sandblasting, use of drilling machines, chipping and power brushing, etc. are considered as hot jobs. Following are steps to control the hazards of hot jobs during shutdown or turnaround;
- A hot job provides a source of ignition and may result in fire or explosion if a favourable environment exists. Potentially hazardous areas include but are not limited to process vessels, pipelines, close drain vessels, reactors, pits of process piping valves or pumps, and confined spaces where gases can accumulate.
- All hot works involve inherent fire risks and hazards. All fire hazards should be considered and evaluated before commencing hot work operations.
- Special procedures and permits are required when hot work is to be performed in a confined space, tank, vessel, or pipeline.
- Whenever possible, avoid hot work and consider alternative methods.
- Before the start of hot work identifies the scope of work, remove potential hazards, isolate the work area with coverings or canopy and then allow for the job.
- Perform gas monitoring in the work area before and during hot work activities. LEL or gas meter should be calibrated.
- Before the hot job properly drain, flush, or purge to remove any hazardous material. Also, during the hot job, continuously monitor all surrounding areas, not just the equipment being worked on—for the presence of any flammable.
- Train personnel on hot work procedures, proper use and calibration of combustible gas detectors, safety equipment, job-specific hazards, and controls.
- Supervise the contractors because they are unfamiliar with your plant-specific hazards and safety rules.
9. Safety Precautions for Couplings and Fittings
Different mechanical fittings and coupling are used to connect the hose pipes e.g Chicago couplings for water or air etc. in the same way, different fittings are used at process pipelines or equipment at drains, bleeders, purges, or blank-off flanges to connect steam, nitrogen or water.
- Failure of any of the fittings or couplings may result in serious incidents like a splash of hot process fluid or steam on the plant employees. Pressurized, nitrogen, or water can also hit the person causing damage or injury.
- All the couplings should be proper according to the size of the drain, or utility point. Use only standard couplings according to the pressure rating.
- In case of leakage isolate pressurized fluid, first, fix it and then resume the activity. Prepare and use specific standard procedures for the safe use of fittings.
10. Flexible and Pressurized Hoses Safety
Flexible and pressurized hoses are used mainly during plant handover for draining, flushing, or purging. Usually, these hose pipes are utilized for Nitrogen, air, water, steam, and hazardous process fluids. Injuries can occur when these hoses break and release pressure hot, cold, or dangerous chemicals. Hazards associated with flexible hoses are described below.
- Pressurized hoses when a break can cause serious Injuries. The injury can be caused by the whipping hose itself, blowing debris, splashing hot streams, or the release of potentially dangerous gas or liquid.
- The sudden release of pressurized fluid may hit the person causing a potential injury or burning due to hot fluid etc.
- The leading cause of hose failure is probably its misuse i.e. use of damaged pipe or not designed for the specific service. Before use, inspect physical condition for torn outer jacket, damaged inner reinforcing, spots, or wear of outer surface.
- Use the hose pipe for the service for which it was designed according to the pressure and temperature rating.
- Use proper couplings, seals, and whip-check safety wires to fix them before pressurizing them with fluid.
- Avoid sharp bends in the hose, these may damage the hose or leakage of the process fluid from fittings. Before taking in service remove the bends.
- A whipping hose is very dangerous and can be stopped by fixing the hose with some metallic wire, a rope or clamps, etc.
- If the hose pipe breaks or the fitting gets open then never try to take hold of it and restore the flow. Clear the area and isolate it from the source.
- Don’t put the hoses haphazardly in the area and remove them immediately after use.
- While crossing the road prevent them by putting metallic covers over them to avoid their damage.
- While removing from the service point, ensure that pressure has been released and the hose has been flushed to remove chemicals.
- Further about hose pipes safety http://www.wermac.org
11. Catalyst Unloading and Loading Safety Hazards
Catalyst handling is one of the major activities in turnaround. Most of the catalysts being used in the refinery are pyrophoric. Loading and unloading normally take place under the inert environment of nitrogen. Wet dumping, using the recommended solution, or water can also be used. Catalyst handling operations have the potential of generating airborne dust, mist, or vapour depending upon the nature of the catalyst involved. These catalyst pollutants have adverse health effects. Further, if catalyst loading and unloading activity involve confined space entry under the Nitrogen atmosphere, then this can become life-threatening activity. Following are some general guidelines, to avoid catalyst handling hazards during turnaround;
- Prepare the catalyst loading and unloading procedures, specific to your site and catalyst.
- For reactors, it is necessary to shut down the process units, in a manner that the catalyst has been converted to a safe condition. For example, in the case of Hydrotreating or Hydrocracking units, the catalyst is dried out with hot hydrogen gas at a high temperature near the design to remove the liquid hydrocarbons from the catalyst surface and cleaning of the reactor. This method is called Hot Hydrogen Stripping.
- Many catalyst operations involve entry into confined spaces. Strictly follow confined space safety and permit procedures for safe execution.
- Normally, pyrophoric catalysts are removed in an inert atmosphere, normally under nitrogen. Detailed procedures for working in inert atmosphere/nitrogen should be strictly followed. This requires suitable standardized and tested breathing equipment for breathing.
- The reactor should be purged of the process liquids and gases as much as possible before catalyst handling operations should start.
- The temperature should also be suitable for the operations. This is often 40°C but ideally, it is near the body temperature of 37°C to prevent heat stress for the operators.
- Vacuum systems and hoses have a risk to generate enough static electricity to ignite combustible atmospheres. Equipment such as conductive hoses should be used also proper earthing should be implemented.
- Catalyst loading and unloading normally involve working at height and with forklifts and cranes.
- Packaging of exhausted catalysts should be under Nitrogen in suitable bags and drums. Immediately, should be sealed after catalyst filling.
- Many substances used in catalysts have hazardous properties that can be linked to adverse health effects. Consult the safety data sheet for safe use.
- Other catalysts-specific hazards may also arise, follow the vendor instructions and procedures for safe handling.
- Health effects from catalyst exposure depend upon the type, composition, and extent of exposure.
- For further study please view Catalyst Handling Procedures to Minimize Exposure.
12. Electrical hazards and Safety Measures
The main hazards of working with electricity are, electric shock and burns from contact with live parts, injury from exposure to arcing, fire from faulty electrical equipment or installations, and explosion caused by unsuitable electrical apparatus or static electricity igniting flammable vapours or dust. Further, electric shocks can also lead to other types of injury, for example by causing a fall from ladders or scaffolding, etc. Numerous jobs involve electrical hazards, the following are the unsafe conditions during shutdown or turnaround that must be avoided;
- Damaged electrical tools and equipment can be very dangerous. Thoroughly check for cracks, cuts, or abrasions on cables, wires, and cords. In case of any defects, repair or replace them on priority.
- Lock Out & Tag Out Procedures should be followed at all times before maintenance and repairs.
- In TA, all the motors of the area should be d-energized, tagged, and locked.
- Using wires of inappropriate size for the current can cause overheating and fires to occur. Use the wire suitable for the operation and can bear the electrical load.
- Power tools, power cables, and distribution panels with damaged parts may expose to shocks and burns.
- Proper grounding will reduce the risk of electrocution. Check proper grounding for all the jobs involving electricity.
- Damaged insulation is a cause of electrocution and open-source spark and should be reported immediately. Replace the cables with the new ones.
- Never operate electrical equipment in wet conditions. Water greatly increases the risk of electrocution especially if the equipment has damaged insulation.
13. Work at Height
Many unsafe conditions may cause incidents due to work at height like fragile roofs, openings in roofs, voids, sloping roofs, deteriorating materials, unprotected edges, unstable or poor access equipment, improper scaffolding platforms, adverse weather conditions, and an untrained workforce.
- Before the job, the platform should be inspected by a specialist and green tagged. If not tagged or red-tagged then don’t use it.
- Don’t overload the platform, only necessary tools and manpower should be at a height.
- There should be a safe and proper approach to the platform. Barricade the ground floor to avoid falling tools hazards for other persons working on the ground.
- Emergency rescue plans should be in place to facilitate the rescue of trapped or fallen workers. Use a safety harness and other proper gear while working at height.
14. Pyrophoric Materials Safety
Pyrophoric materials ignite themselves spontaneously upon contact with oxygen or moisture. Pyrophoric materials can be solid, liquid, or gas. The Pyrophoric materials create fire and explosion hazards. Pyrophoric materials are often found in refinery piping, tanks, and vessels. Pyrophoric Iron Sulfide, spent catalysts, etc. are common examples in an oil refinery.
- To avoid accidental ignition, a protective anhydrous inert atmosphere of nitrogen gas must be maintained over the surface of the pyrophoric material at all times. The chemical method can also be applied to suppress the pyrophoric nature of the chemical.
- Implement and follow pyrophoric materials handling plan when emptying vessels and tanks. The plan should include, how to handle pyrophoric materials and avoid the formation of an explosive mixture.
- In TAs the risks of exposure are very high because vessels are opened for cleaning, inspection, and repair. If not handled properly, severe fire can happen.
- Pyrophoric sludges or materials can also be suppressed by applying water showers upon exposure to the atmosphere, or material can be dipped in the water containers.
- Fire-resistant gloves must be worn when handling pyrophoric materials.
- Containers carrying pyrophoric materials must be clearly labelled with the complete chemical name and hazard warning.
15. SIMOPS (Simultaneous Operations)
operations (SIMOPs) are situations in processes where two or more operations or activities occur at the same time and place. They may interfere or clash with each other and may involve risks that are not identified when each activity is considered by itself. Thus, they can increase the risks of the activities or create new risks. Several major process industry accidents have involved simultaneous operations. This might be one of the biggest risks of turnaround or shutdown.
- In TA multiple activities are being performed but by different teams. In addition, the congested plant also worsens the situation. For example on the same vessel inside welding, outside inspection or adjacent scaffolding is in an example of SIMOP.
- Simultaneous operations often involve work in the same area by multiple contractors and subcontractors or multi-disciplinary workers whose work may overlap and/or interact. For example, maintenance activities in turnaround near active equipment such as crane lifts over a storage tank containing a toxic material may result in a release from dropped objects. Similarly, a maintenance activity near another process operation such as hot work in the vicinity of a vessel containing a flammable material may result in a fire.
- The best method to avoid incidents in SIMOPS is to properly plan the jobs and avoid the hurry while issuing the job permits. In addition, apply strong administrative controls to separate the domains of different jobs to avoid interference.
16. Confined Space
“Confined space” is a space that: (1) is large enough and so designed that an employee cannot easily enter and stay in that space to perform assigned work; (2) Has restricted entry or exit (for example, tanks, vessels, heaters, furnace, boiler, towers, pits, etc.(3) is not designed for continuous stay and work. The following are hazards in confined spaces and need to be addressed before entry into the confined space;
- Insufficient oxygen due to the presence of other gases (i.e. toxic or inert) might be in the process vessels that could make the worker ill or lose consciousness and in the adverse situation may lead to the death of a worker. These hazards can be eliminated through proper ventilation arrangements and monitoring of the atmosphere by gas meters.
- Flammable gases or liquids can be removed by adopting proper purging & flushing. For hot jobs in confined space at any cost, Lower Explosive Limit must be zero.
- Equipment should be positively isolated from the processing system. As a general rule, all the ins and outs must be blinded or disconnected.
- Sludge containing toxic gases e.g in the sour water tank, should be properly flushed, make wet, or chemically neutralized before entering.
- In an oxygen-deficient atmosphere, use standardized live breathing apparatus.
- A rescue plan must be prepared before entry and implemented with trained persons.
- A standby man must be present at the entry point of the confined space and be in contact with the person inside.
- Workers performing jobs inside the confined space must be physically fit.
- Chemical exposures to the workers due to skin contact or ingestion and inhalation. These can be controlled by purging and flushing the vessel. Also, use the required PPES to avoid the effects of these hazards.
- Physical hazards such as noise, heat, cold, radiation, vibration, electrical, and inadequate lighting can also be faced.
- Safety hazards such as moving parts of equipment can be avoided by isolation from power sources.
17. Poor House Keeping
Poor housekeeping might result in fire, slip, trip, fall, and injuries of employees in TA because of multiple activities. Good Housekeeping is essential for a safe TA. It will result in fewer accidents, minimize the impact on the environment, and will reduce hazards.
- All oil spills must be avoided. In the event of a spill, a prompt cleanup will minimize slipping, environmental impact, and fire hazards.
- Passages and walkways must be kept free of welding rods, tools, hoses, extension cords, and other objects which create stumbling hazards. Cleaning up the area where you are working is part of the job.
- Place the tools in the proper place, and remove the unnecessary item from the area.
18. Communication Hazards During Turnaround
Good communication is the key to safety at process plants. If shift handovers are not proper then the consequences can be devastating.
- According to the data, more than 40% of plant incidents occur during start-up, shutdown, and shift handover periods. Operations personnel must convey the specific state of the process at the point of shift handover in verbal as well as written format.
- Missing, wrong, unnecessary, poor-quality information may lead to miss understanding. Properly record of all activities with time during the duty hours e.g. Isolation, blinding, activities in progress, specific location, equipment tags, work permits, etc. must be conveyed to the next shift reliever.
- Information should be to the point and brief. Unnecessary extra information, may bore the person to read the complete logbook, therefore missing the important one.
19. Austenitic Stainless Steel Protection
Precautions should be taken to protect austenitic stainless steel equipment against conditions that could lead to stress corrosion cracking.
- In Hydrotreating or Hydrocracking units, reactors, heaters, combined feed exchangers, and associated piping are made of Austenitic Stainless Steel. These should be neutralized with soda ash solution before their opening to the atmosphere.
- Follow specific procedures for protection to avoid polythionic acid attack which will result in stress corrosion cracking in Austenitic Stainless Steel.
- Oxygen, water, and Iron Sulfide contribute to polythionic acid, and to avoid its attack any one of these must be removed from the system.
- Before steam out and water flushing of other connected circuits, isolate the Austenitic Steel system by blinding.
20. Extensive Working Hours
Extra working hours may lead to fatigue, illness, stress, poor work-life balance, and other health risks to the employees and they experience numerous mental, physical, and social effects.
- Employee performance levels could also be lowered. Normally, during the TA 12 hours, night and day shifts are planned.
- Take the breaks designated by the management and utilize them effectively to relax. Apply administrative controls and balance the working hours of its staff.
- Plan the day, night, and rests equally for all the employees. Provide proper refreshment breaks during working hours.
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