As we have discussed many times, UNLOADING/LOADING Hazardous Materials to/from a bulk DOT container is often times one of the highest risks on a plant site. And when the hazardous material is a liquefied compressed gas, the risks escalate quickly! Two of the more common liquefied compressed gases are LPG and NH3, which fall under 49 CFR § 173.315(n)(2), requiring…
... bulk transport vehicles transporting certain liquefied compressed gases, including NH3, be outfitted with passive emergency shutdown control equipment. The passive shutdown system will automatically shut off the flow of product from the cargo tank motor vehicle—without the need for human intervention—within 20 seconds of an unintentional release caused by “a complete separation of a liquid delivery hose.”
Two types of passive shutdown systems commonly used by the industry include:
1) A hose that operates in the event of a mechanical failure (the hose involved with the incident utilized Smart-Hose™ Technology); and
2) A permanently mounted, computer-controlled leak detection/shutdown system.
49 CFR § 173.315(n)(2)
Cargo tank motor vehicles in other than metered delivery service. A cargo tank motor vehicle in other than metered delivery service must have a means to automatically shut off the flow of product without the need for human intervention within 20 seconds of an unintentional release caused by a complete separation of a liquid delivery hose (passive shut-down capability).
(i) Designed flow of product through a bypass in the valve is acceptable when authorized by this subchapter.
(ii) The design for the means to automatically shut off product flow must be certified by a Design Certifying Engineer. The certification must consider any specifications of the original component manufacturer and must explain how the passive means to shut off the flow of product operates. It must also outline the parameters (e.g., temperature, pressure, types of product) within which the passive means to shut off the flow of product is designed to operate. All components of the discharge system that are integral to the design must be included in the certification. A copy of the design certification must be provided to the owner of the cargo tank motor vehicle on which the equipment will be installed.
(iii) Installation must be performed under the supervision of a Registered Inspector unless the equipment is installed and removed as part of regular operation (e.g., a hose). The Registered Inspector must certify that the equipment is installed and tested, if it is possible to do so without damaging the equipment, in accordance with the Design Certifying Engineer’s certification. The Registered Inspector must provide the certification to the owner of the cargo tank motor vehicle.
EMERGENCY DISCHARGE CONTROL EQUIPMENT (§ 173.315)
The HMR requires emergency discharge control equipment on cargo tanks authorized for transport of LCG. The performance standard of the equipment
is keyed to the degree of risk of the material to be transported. The HMR specifies two types of emergency discharge controls:
Passive Shut-Down Capability: This performance standard requires that equipment be capable of automatically shutting off the flow of product without human intervention within 20 seconds of an unintentional release caused by the complete separation of a liquid delivery hose. Technological advances in equipment since this standard was incorporated into the HMR allow for operation in a much shorter amount of time (i.e., within a half second). Also, this performance standard requires automatic operation in the event of a complete separation of the delivery hose. Current technologies have advanced such that automatic operation can occur in the event of a partial (e.g., a hole or tear) or complete separation of the delivery hose.
Off-truck Remote Shut-Off Capability: This performance standard requires off-truck remote shut-off equipment to close the internal stop valve and shut off the engine and auxiliary power when activated by the qualified person attending the unloading operation. It must function reliably at a distance up to 150 feet. Equipment employing a wireless transmitter/receiver must demonstrate that it will close the internal self-closing stop valve and shut off all motive and auxiliary power equipment at a distance of 300 feet under optimum conditions. Equipment not employing a wireless transmitter/receiver must demonstrate functioning at the maximum length of the delivery hose.
Note: Under certain conditions, a query system may be used to satisfy this performance standard. A query system operates on a timing mechanism where the system will automatically shut down unless queried (“triggered”) by the operator to keep the system engaged. When such a system is used, it must close the internal stop valve and shut off all motive and auxiliary power equipment unless queried at least once every five minutes.
CERTIFICATION OF EMERGENCY DISCHARGE CONTROL EQUIPMENT (§ 173.315)
The HMR includes specific requirements for certifying the design and installation of emergency discharge control equipment.
Passive shut-down equipment: The design for each passive shut-down system must be certified by a Design Certifying Engineer (DCE). The certification must consider any manufacturing specifications for components used in the system, explain how the system operates, and outline the parameters (such as temperature, pressure, types of product) within which the system is designed to operate. Installation must be performed under the supervision of a Registered Inspector who must certify that the equipment is installed and tested according to the DCE’s certification.
Off-truck Remote Shut-off Equipment
Must be installed under the supervision of a Registered Inspector, who must certify that the equipment is installed according to the original component manufacturer’s specifications and is tested in accordance with the HMR
ADDITIONAl EMERGENCY DISCHARGE CONTROL EQUIPMENT (§ 173.315) (FUSIBlE ELEMENTS)
Cargo tanks authorized for transport of LCG also must have each liquid or vaporcdischarge outlet fitted with a primary discharge control system as is required
for a DOT specification MC 331 cargo tank and defined in § 178.337-1(g). The system must include a thermal means of closure for each internal self-closing stop valve, and remote operators must activate at a temperature of 250° F or less. Links between closures and remote operators must be corrosion resistant and effective in all types of environmental conditions incident to unloading of a product. Conditions for exception from this requirement are referenced in § 178.337-8(a)(4).
OPERATING PROCEDURES (§§ 177.834 and 177.840)
The HMR includes several additional operating procedure requirements. We also encourage operators of the cargo tanks used in LCG service to use the best
available technology to reduce the likelihood of serious consequences from unintentional releases.
WRITTEN PROCEDURES: The operator of a cargo tank motor vehicle subject to the emergency discharge control equipment requirement must carry, on or with the vehicle, written emergency discharge control procedures for all delivery operations. The procedures must describe the emergency discharge control system features. For a passive shut-down system, the procedures must describe the parameters within which the system is designed to function. For example, if your vehicle’s emergency discharge control system is certified to operate at or above a specific pressure or temperature, you must include this information. The written procedures also must include the process to follow if a facility-provided delivery hose is used when the cargo tank is equipped with a delivery hose assembly meeting the passive shut-down capability requirement.
ATTENDANCE REQUIREMENTS: The HMR includes general requirements for attendance of loading and unloading operations. The attendance requirements specific to the unloading of LCG as they would apply to cargo tank operations are as follows:
- If an LCG other than liquefied petroleum gas (LPG) or anhydrous ammonia (NH3) is being unloaded from a cargo tank, a qualified person must remain within 25 feet of the cargo tank and must have an unobstructed view of the cargo tank and delivery hose to the maximum extent practicable during the unloading operation.
- If LPG or NH3 is being unloaded from a cargo tank in metered delivery service, and the cargo tank has a capacity of 3,500 water gallons or less, a qualified person must remain within 150 feet of the cargo tank and within 25 feet of the delivery hose during the unloading operation. For an unloading operation taking more than five minutes, this person must observe the cargotank and the receiving container at least once every five minutes.
- If LPG or NH3 is being unloaded from a cargo tank in metered delivery service, and the cargo tank has a capacity greater than 3,500 water gallons, a qualified person must remain within 150 feet of the cargo tank and within 25 feet of the delivery hose during the unloading operation. The qualified person must have an unobstructed view of the cargo tank and delivery hose to the maximum extent practicable. For instances where the qualified person cannot maintain an unobstructed view, the cargo tank must be equipped with a passive shut-down system. For an off-truck remote shut-off system with a query feature that will automatically shut down unloading unless prompted every five minutes, the qualified person must observe both the cargo tank and the receiving container at least once every five minutes.
- If LPG or NH3 is being unloaded from a cargo tank in other-than-metered delivery service, a qualified person must remain within 25 feet of the cargo tank and must have an unobstructed view of the cargo tank and delivery hose to the maximum extent practicable during the unloading operation (for example, except when activating controls or monitoring the receiving container).
Note: A “qualified person” is aware of the nature of the hazardous material being loaded or unloaded, has been instructed on the procedure(s) to be followed in emergencies, and is authorized to move the cargo tank and has the means to do so.
PRETRANSFER SAFETY CHECK:
Before an LCG is unloaded and after pressure in the discharge system has equalized with the pressure in the cargo tank, a qualified person must check the components of the discharge system (including Liquefied Compressed Gases: Compliance Assistance Guide 7 the delivery hose assembly and piping) to ensure the system is in good operating condition. The connections must be secure, and the system must not contain any obvious defects. The check must be done on the components that are readily observed during the normal course of the unloading operation, and good condition and defects should be determined through visual observation and by listening for unusual sounds. Review the rejection criteria in this guide to assist with determining whether the discharge system is in good condition for unloading. Operators are not required to have the qualified person use an instrument to assist with the safety check or exceed reasonable lengths to
conduct the safety check for those components not readily visible.
EMERGENCY SHUTDOWN:
In the event of an unintentional release, the qualified person conducting the unloading operation of the cargo tank motor vehicle must promptly shut the internal self-closing valve, or other primary means of closure, and shut down all motive and auxiliary power equipment associated with the cargo tank motor vehicle.
Daily Test of Off-truck Remote Shut-off Activation Device:
The operator of a cargo tank motor vehicle equipped with such a system must successfully test the activation device of the system within eighteen (18) hours prior to the first delivery of any given day of planned deliveries. If a wireless device is used, the test of the device must be conducted at least 150 feet from the cargo tank. The test does not have to be conducted from an obstructed view (i.e., the cargo tank may be visible).
Use of facility-provided delivery hose assemblies:
A cargo tank motor vehicle equipped with a delivery hose assembly that satisfies the passive-shut-down capability performance standard may be unloaded using a delivery hose assembly provided by the receiving facility under the following conditions:
- The qualified person handling the unloading must visually examine the facility delivery hose assembly for obvious defects in the same manner as done under the safety check for the cargo tank motor vehicle discharge system;
- The qualified person must remain within arm’s reach of the manual means of closure for the internal self-closing stop valve, except for short periods when it is necessary to activate controls or monitor the receiving container; and
- If the facility-provided delivery hose assembly is such that it satisfies the passive shut-down capability performance standard, the qualified person
handling the unloading operation may remain in attendance in accordance with the appropriate attendance requirements outlined above.
POSSESSION OF ACTIVATION DEVICE:
For a cargo tank motor vehicle with a required off-truck remote shut-off capability, the qualified person attending the unloading operation must be, at all times during the unloading process, in possession of the device that activates the shut-down equipment. The qualified person does not have to be in possession at all times if the device is part of a system that will shut off the unloading operation without human intervention in the event of a leak or separation in the hose (i.e., if it is part of a system with passive shut-down capability).
Note: Unloading of chlorine from a cargo tank motor vehicle must be performed in accordance with Section 3 of the 4th edtion (October 2003) of Chlorine Institute Pamphlet 57, “Emergency Shut-off Systems for Bulk Transfer of Chlorine.”