3D MODEL REVIEW OF REFINERY UNITS 1

[p1a9l7a5]

We have to review 3D Model of a new unit coming up in our refinery.

What points to be checked with respect to Safety & process safety?

 

[EmmanuelTop]

Here are items extracted from a few checklists. You may wish to go through and see what is applicable for your unit:

* Check the accessibility of the unit for manual fire-fighting operations.
* Can fire water headers be safely accessed?
* Can a fire truck manoeuvre easily?
* Can all locations be reached by a fire truck if one road is blocked?
* Fire-risk pumps handling liquids above their auto-ignition temperature or handling very light liquids such as propane and butane shall be located:
− in the open;
− in non-congested areas;
− at least 3 m from pipe racks and major process structures;
− so that they are accessible for fire fighting;
− so that escalation of a possible pool fire from e.g. a seal failure is prevented.
* Only pumps handling burnable liquids below their auto-ignition temperature may be placed in between a pipe rack and equipment like columns.
* Only pumps handling inflammable liquids may be placed under pipe racks or structures.
* Can hot pumps be properly protected by fire water spray systems or monitors?
* Check location of fire hydrants, fixed, mobile and portable fire fighting equipment. Consider this in relation to the equipment to be protected and the likelihood of a fire.
* Check presence of fireproofing of steel structures with respect to credible fires. Protect vessels, columns, flare headers, main pipe racks, if required.
* Check whether the layout of water spray pipes and nozzles is adequate to cool LPG vessels.
* Are fire detectors and tubing present on hot pumps and LPG pumps?
* Are detectors for fire, gas, smoke and H2S strategically located?
* Are warning and alarm lights for fire, gas, smoke and H2S strategically located?
* Are fire water deluge manifolds safely located in relation to the equipment they protect?
* Are CCTV cameras for plant monitoring strategically located to enable a good view of the high risk areas?
* Check if emergency showers and eye bath showers are strategically located, e.g. near equipment handling caustic, ammonia, and aggressive chemicals. Valves are not allowed between the main header and the safety equipment.
* Check the flange orientation of liquid full LPG systems.
* Check whether fire fighting facilities are adequately provided in accordance with the applicable standard or specification. For example, depending on the project standard, water spray systems should be provided for the following services:
- For the pumps operating higher than its auto-ignition temperature.
- For the non-insulated vessels, containing large amount of LPG.
* Confirm that the ladders for escape are provided at platforms and structures in accordance with clients' requirements.
* Confirm the remote switches of emergency valves are installed at safe locations, away from the possible hazardous source. They should be located at grade and 15m or more away from the valve concerned. It is preferable that they are grouped together with in a collective area.
* Confirm that the safety shower and eye washer are provided near caustic, acid and mine-containing
equipment.
* Confirm the installed location of units for fire-fighting and rescue work is accessible.
* Check for possible piping and cable, etc., which might cause head bumping or tripping.
* For leak consideration of hydrogen service with high pressure and temperature, confirm that the valves on emergency and smothering steam headers are accessible and located at a safe distance from these items of equipment, whenever this system is applied.
* Utility stations should be provided thoroughly to cover the plot area. Confirm that the nitrogen hose station is available on the platform of the reactor for catalyst unloading operation.
* The following manual shut-off valves should be located at grade and 15 meters or more away from the heater. It is preferable that they are grouped together in a collective area.
- Isolation valves of fuel oil supply and return
- Isolation valve of fuel gas supply
- Isolation valve of snuffing steam
- Isolation valve of heater coil purge gas
* Manual shut-off valves for hot oil service should be located at an accessible position and away from the possible source of fire.
* Drain valves should basically be located so that operators can see the drain effluent whde manipulating the valve. However, length of the dead end above the drain valve should be minimized to avoid sludge accumulation. Provide drain lines as straight as possible upstream of the drain valve. In the case of drain valve at the vessel bottom and pump suction, locate the drain connection at the lowest position of the either side of the pump suction, and upstream of the isolation valve.
* Direction of the steam exhaust should be reviewed carefully, to avoid spray of live steam and hot water droplets on personnel.
* Difference of thermal expansion should be considered when a continuous platform is supported by more than one structure.
* Make sure insulation for personal protection is provided on the accessible part of hot lines such as the overhead vapor line and steam trap outlet to the return line.
* Sampling points should not be provided near firing facilities such as furnaces, boilers, incinerators, etc., and preferably grouped together so that sampling could be done easily.
* Venting lines should be adequately extended to high elevation for safe discharge. Area classification sometimes requires the extension of a venting line more than 7.5 meters above the vessel. Confirm the applicable code and practice for the area classification on the vertical distance requirement. These venting points include:
- Chemical drum vent
- Sump pit vent

Dejan IVANOVIC
Process Engineer, MSChE