One of the more common omissions in SOPs is the inclusion of all the “safety systems and their functions” involved in the execution of the SOP. In this article, I will use the task of Truck/Railcar Unloading a Flammable Liquid to demonstrate the types of safety systems and their functions that may need to be included in the Unloading SOP.
Let’s begin with the PHA… yes, I mean the Process Hazards Analysis. Several years ago I wrote an article about using the PHA to write the SOPs for the process. The PHA is an excellent starting point, as in the PHA ALL of the safety systems and their functions will be included in the various deviation scenarios identified in the PHA. So we go back to the Truck/Railcar Unloading Node of the PHA and we can see the “Safeguards” listed for each deviation scenario. Without question, these listed safeguards belong in the Unloading SOP. Here is a sampling of Safety Systems and their functions that may need to be listed in an Unloading SOP for flammable liquids:
1) Electrical Classification is Class I Div 1/2
2) Emergency Shutdown System
3) Bonding and Grounding, including permissive safety systems if used
4) Secondary Containment in Unloading Area and Tank Farm
5) High Level Alarm on receiving tank
6) High-High Level Interlock
7) LEL Detectors in Unloading Area and Tank Farm
8) Fire Valves
9) Conservation Vents (pressure and vacuum)
10) Flame Arrestor(s)
1) Electrical Classification is Class I Div 1/2 should be listed as a safeguard as it should be VERY CLEAR to the personnel involved in unloading the flammable liquid that the CONTROL of IGNITION sources is WITHOUT a doubt one of the most fundamental safety needs. Personnel needs to understand and have the ability to identify IMPROPER equipment in the area BEFORE the transfer begins. There are countless examples how improper equipment gets introduced into these HAZLOCs, but none the less, the personnel who will carry out the task NEED to have the ability to recognize the introduction of ignition sources to the working area.
2) Emergency Shutdown System may not be specifically called for in any OSHA or DOT requirements; however, there are many state Fire Codes that do require such a safety system for unloading flammable liquids, or any hazardous materials for that matter. For example, the IFC states…
5003.2.2.1 Design and construction. Piping, tubing, valves, fittings and related components used for hazardous materials shall be in accordance with the following:
1. Piping, tubing, valves, fittings and related components shall be designed and fabricated from materials that are compatible with the material to be contained and shall be of adequate strength and durability to withstand the pressure, structural and seismic stress and exposure to which they are subject.
2. Piping and tubing shall be identified in accordance with ASME A13.1 to indicate the material conveyed.
3. Readily accessible manual valves or automatic remotely activated fail-safe emergency shutoff valves shall be installed on supply piping and tubing at the following locations:
3.1. The point of use.
3.2. The tank, cylinder or bulk source.
4. Manual emergency shutoff valves and controls for remotely activated emergency shutoff valves shall be identified and the location shall be clearly visible, accessible and indicated by means of a sign.
5. Backflow prevention or check valves shall be provided when the backflow of hazardous materials could create a hazardous condition or cause the unauthorized discharge of hazardous materials.
These systems need to be included in the SOP along with how they actually function. The SOP needs to call out the location(s) of the ESD button(s) and what actually happens when the ESD button(s) is activated, as well as any follow-up actions the operator needs to take to bring the process to a safe state. Activation of the ESD may stop pumps, close valves, sound alarms, etc.; all of which needs to be explained in the SOP. NOTE: this information will also play a vital role in the MI procedure for the functional testing of this safety system.
3) Bonding and Grounding, including permissive safety systems if used, are one of the most fundamental safety requirement for flammable liquid transfers, yet they are often times listed in the steps of the SOP but not actually explained how they operate in the “Safety Systems and their functions” section of the SOP. This is especially true if the unloading system utilizes a “permissive grounding system”. These “permissive grounding systems” are essentially an interlock system that stops the flow of flammable liquids when there is a loss of proper “ground”, as well as preventing the transfer from even starting when a proper ground is not present. Operators need to know how this system works, the set point for the activation of the system (e.g. how many ohms). The SOP also needs to provide “steps to correct” should this safety system trip.
4) Secondary Containment in Unloading Area and Tank Farm play a critical role in mitigating the loss of primary containment(LOPC) and overflow events. It is not expected that the operator would do an integrity inspection on the containment, but an inspection to ensure the containment basin(s) are EMPTY (of rainwater and “storage”) as well as their drain valve(s) SECURED CLOSED.
5) High-Level Alarm on receiving tank should be listed, as well as the level at which it sounded. The SOP should explain the tone of the alarm and list any visual alarm indicators as well.
6) High-High Level Interlock will be listed much like the “permissive grounding system”. We need to include the set points of when the interlock is tripped, what actions the interlock takes, and any actions the operator must take when it is tripped.
7) LEL Detectors in Unloading Area and Tank Farm play a role in early detection of an LOPC or Overflow event. If they are used, we need to list their locations, alarm set points (keeping in mind some detectors may have different set points), and alarm tones. And don’t forget to provide “steps to correct” when these detectors alarm!!
8) Fire Valves are often times part of the design of the tank farm. OSHA requires these valves on INSIDE FLAMMABLE LIQUID storage tanks and almost all state fire codes do as well; yet many companies see the value in the valves and use them on ALL storage tanks. Either way, these valves are a safety system which PREVENTS flow of flammable liquids in the event of a fire around the tank. A simple listing of the valves and the fact that they have a fusible link and are FAIL SAFE CLOSED valves will most likely suffice.
9) Conservation Vent (pressure and vacuum) are the last of the basic safety systems. These devices sit on the tank vent and reduce emissions of flammable vapors, as well as provide protection from creating a vacuum within the atmospheric tank. Although these devices usually require NO INTERACTION with the personnel doing the unloading, yet it is still a safety system that protects the tank, as well as reduces flammable vapor discharge.
10) Flame Arrestor(s) are not required in some applications but are often found in almost all vapor discharge locations. These devices require no interaction between the personnel doing the unloading, but the personnel does need to understand their function. In almost all of my Flammable Liquid Unloading procedures, the deviation of too much pressure in the atmospheric storage tank involved the inspection of the flame arrestor(s) for pluggage.
So these are some of the more common safety systems involved in unloading flammable liquids from transport containers to bulk storage tanks. Your process may include others, but these are meant to serve as examples. All of your safety systems should be listed in the Unloading Node of your PHA. Using the Process Safety Information will permit you to define their function for the personnel who will be executing the unloading.
NOTE: Many bulk tanks containing flammable liquids also utilize Nitrogen Blanketing Systems. If this is the case, these safety systems require a bit more information, but will certainly be required to be listed as a safety system within the unloading SOP.