Chemical Spills During Loading

Contents

• Introduction
• Notice Summary
• Applicability
• Equipment Description
• Events Summary
• Signifigance of Events
• Causes
• Corrective Actions
• References
• Safety Notices Issued

Introduction

This notice is one in a series of publications issued by the Office of Nuclear and Facility Safety to share nuclear safety information throughout the Department of Energy complex. For more information, contact Dick Trevillian, Office of Operating Experience Analysis and Feedback, Office of Nuclear and Facility Safety, U.S. Department of Energy, Washington, DC 20585, telephone (301) 903-3074. This Safety Notice should be processed as an external source of lessons- learned information as described in DOE-STD-7501-95, Development of DOE Lessons-Learned Programs.

Safety Notices are distributed to U.S. Department of Energy Program Offices, Field Offices, and contractors who have responsibility for the operation and maintenance of nuclear and related facilities, and to other organizations involved in nuclear safety. Written requests to be added to or deleted from the distribution of Safety Notices should be sent to: Richard L. Trevillian, EH-33, Room 2029 CXXI/3, U.S. Department of Energy, Washington, DC 20585.

The Office of Information Management maintains a file of Safety Notices and supporting information. Copies can be obtained by contacting the Office of Information Management at (301) 903-0449 or by writing to the Office of Information Management, U.S. Department of Energy, EH-72/Suite 100, CXXI/3, Washington, DC 20585.

Notice Summary

This Notice contains lessons learned regarding chemical spills during loading and unloading tanker trucks. Office of Nuclear and Facility Safety (NFS) engineers determined that more than 40 such spills were reported through the Occurrence Reporting and Processing System (ORPS). Depending on the material spilled and the quantity, spills may be a hazard to public health, worker health and safety, and the environment, and may be very costly.

Spills during transfers within a facility are not covered in this Notice, but will be addressed separately.

Applicability

This Notice is applicable to the conduct of operations at facilities owned or operated by DOE regarding loading and unloading tanker trucks. NFS recommends that operators of DOE facilities become familiar with lessons learned and apply them to improve safety during chemical transfers.

No specific action or response is required as a result of this Notice. NFS recommends processing this Notice in accordance with DOE-STD-7501-95¹.

Equipment Description

A variety of bulk chemicals are used at DOE facilities and many of these are transported in liquid form in tanker trucks or railcars. The chemicals must then be unloaded at the facility. Also, some facilities may produce wastes that must be transported to another location in tanker trucks.

The type of equipment used to transfer chemicals between tanker trucks and storage tanks varies, depending on the characteristics of the chemicals. Primary characteristics that determine the type of equipment are chemical compatibility, flammability, and storage temperature and pressure.

Liquids transported by tanker trucks fall into three categories of temperature and pressure: normal liquids, liquefied gases, and cryogenic liquids. A normal liquid is liquid at atmospheric pressure over the normal range of air temperature. A liquefied gas is a vapor at normal temperatures and atmospheric pressure and is kept liquid by pressure. Chlorine is often shipped as a liquefied gas. A cryogenic liquid is a vapor at normal temperatures, but is kept liquid by cooling it below its boiling point. Liquid nitrogen is shipped as a cryogenic liquid. Liquids in any of these categories may be toxic, flammable, or both.

Normal liquids are transferred at low pressures. Transfer systems for liquefied gases must accommodate the higher pressures required. Transfer systems for cryogenic liquids must be able to handle the temperatures involved. Additionally, materials in the transfer system must be chemically compatible with the liquid being transferred. When transferring flammable liquids, the tanker truck and transfer lines must be properly bonded and grounded to prevent sparking before transfer begins.

Low-pressure transfers may be done in two ways: using a liquid transfer pump or using pressure to displace the liquid. If the liquid is pumped, a vapor transfer line may be used to return the vapor displaced from the receiving tank to the source tank. This is important for toxic or flammable vapor that should not be released to the atmosphere. This is shown in Figure 1, which is adapted from the Emergency Response Manual for NFPA 472². If pressure is used, vapor displaced from the receiving tank can be vented to a scrubber, as shown in Figure 2². For many liquids, either transfer method can be used. Materials with toxic or flammable vapor are handled better by a transfer pump system with a return line. Corrosive materials are handled better by pressure displacement, which eliminates the requirement for a corrosion-resistant pump.

Liquefied gases are liquids with very low boiling points, such as nitrogen, oxygen and hydrogen. For liquefied gases, a compressor is required on the return line if the displaced vapor is returned to the source tank. This is shown in Figure 3². Gases that are normally found in the atmosphere, such as nitrogen, may be released from an elevated vent instead of being returned to the source tank.

Events Summary

Figure 4 shows the distribution of material spilled as reported by ORPS. Forty-two percent if the spills involved fuels and oils; 23 percent were water contaminated with radioactive materials or chemicals; 10 percent were chemical or radioactive waste; and the remaining 25 percent involved a variety of acids, caustics, and other toxic materials. Spill amounts ranged from very small to 3,000 gallons. While the consequences of some events were minimal, similar spills of other materials could have a major safety impact. Several representative events are described in the following paragraphs.

On February 10, 1991, at the Savannah River K-Reactor site, fuel oil overflowed from the vent of a tanker truck during unloading.³ Approximately twenty-five to thirty gallons of fuel oil spilled on the ground and asphalt.

The truck driver, an employee of the fuel-oil supplier, set the transfer pump to draw from the storage tank and discharge into the truck tank that was already full. Neither the tanker fill connection nor the fill line on the facility storage tank had check valves to prevent flow in the wrong direction. Also, the off-loading fuel pump on the tanker was not labeled to indicate suction and discharge.

On October 12, 1993, at EG&G Idaho, approximately 1,540 gallons of diesel fuel was released through an open drain valve on a fuel tank in the Central Facilities Area Tank Farm.⁴ The fuel was contained within the berm area of the Tank Farm.

The inlet valve on the tank piping system was replaced during the week before the release. Before replacing the valve, the craftsman transferred the contents of the tank to a different tank, which required opening the outlet valve on the first tank. He did not close the outlet valve when he finished the maintenance work.

A diesel vendor bringing fuel to the Tank Farm was accompanied to the tank by a warehouseman to help transfer fuel from the delivery vehicle to the tank. The warehouseman claims he visually checked the outlet valve on the tank, but he did not notice that the valve was open. The valve is not equipped with a position indicator, which should be normal when it is important to be certain of the valve position. The procedure for Tank Farm operations did not contain instructions to verify that the drain valve was closed before starting filling operations.

On June 14, 1995, at Rocky Flats, a tank was pressure filled with a 35 percent hydrochloric acid solution from a tanker truck.⁵ When the operator finished filling the tank, he applied 17 psi air pressure to purge the transfer line of residual acid. The air pressure, applied at the bottom of the tank, raised the acid level in the tank and caused approximately 60 to 70 gallons of acid to be released from the tank overflow tube into the secondary containment. The Fire Department assessed the scene and determined that the spill was in containment and there was no immediate danger to personnel or the environment.

To eliminate future spills, the diameter of the vent pipe was increased by 6 inches allow adequate venting during clearing operations. Calculations on the method for filling the tank and the air flow experienced at the end of a fill disclosed that the original design specification for the vent pipe diameter was too small.

On June 30, 1995, at the Idaho National Engineering Laboratory, an operator in the Test Reactor Area unloaded concentrated sulfuric acid from a tanker into a storage tank.⁶ He used an approved procedure and dressed in a full acid suit, chemical goggles, and face shield as prescribed by the procedure.

After unloading the acid, he purged the empty tanker truck and the tank fill line with 25 psig compressed air. He noticed a heavy mist of sulfuric acid fumes coming from the outside vent of the tank. He secured the plant air and line to the tank and noticed a puddle of acid up to 1 inch deep and approximately 25 by 50 feet that had accumulated next to the tank vent.

The operator took the most direct path to a telephone to report the problem, which took him through the acid mist. Some acid seeped under his face shield and caused a stinging sensation on his cheek. He reported the problem and flushed his face with water. A nurse responded to his call, provided first aid and sent him to a medical facility for evaluation. He was released without treatment.

A faulty level instrument led the operator to underestimate the amount of acid in the storage tank and overfill it. The tank level system (an air bubbler system with an electronic readout) indicated that the tank was only 77 percent full when it was completely full.

On December 14, 1995, a propane delivery driver connected his truck tank line to the wrong port of a propane tank at a mercury retort plant at Idaho National Engineering Laboratory, causing a propane release, plant shutdown, and evacuation of the facility.⁷ Safety controls actuated as designed.

The trailer-mounted mercury retort plant uses propane heaters to heat mercury-contaminated soil, driving off the mercury and leaving clean soil that can be returned to the environment. There were no overexposures to propane, and no injuries, fires, or explosions were caused by the incident.

The propane delivery driver, with less than two months experience, arrived on site to fill a 10,000-gallon propane tank. He attempted to connect his truck to the liquid fill line on the tank but could not obtain a good seal. He went to the shift supervisor's office to call his company. The company advisor told him to connect to the vapor outlet on the plant systems side of the tank. Without consulting the shift supervisor on site, the driver connected to the vapor outlet, opened a valve that was not locked or tagged, and started the fill.

The vapor outlet was piped to the plant burner fuel distribution system. Introduction of liquid propane to the system caused excessive vapor pressure, which caused overpressure controls to shut down burner ignition and pressure relief valves to actuate. Retort operators noticed the release and, following procedures, shut down the propane delivery system, manually closed distribution system valves, verified burner flame cessation, and performed an emergency shutdown of electrical systems. Project personnel, in accordance with Health and Safety Plan provisions, evacuated to a safe zone.

The Fire Department assessed conditions and concurred with temporary restart of electrical systems to allow a controlled temperature reduction in the retort to minimize equipment damage. When conditions were stabilized and safe, retort operators restarted electrical systems and initiated a normal retort shutdown. Engineers estimated that 30 pounds of propane were released to work environments during the initial event and another 10 pounds during recovery. Retort operators were exposed, but no one had indicated adverse effects at the time of a critique later in the day.

Investigators determined that the root cause of the event was insufficient training for the propane delivery driver on delivery techniques and the facility piping configuration. Contributing causes included (1) lack of a procedure that identified the liquid line as the only allowed fill connection; (2) lack of communication among the propane delivery driver, his company, and project personnel concerning planned actions; and (3) a non-standard propane tank at the retort plant. The tank had a connection on the vapor line that should have been locked or tagged to prevent use of the vapor line for a fill line.

Significance of Events

Proper handling of chemicals is essential to workplace and public safety. Exposure to toxic chemicals causes the deaths of more than a hundred workers in a typical year. Types of damage to human health that can be caused by chemical spills include the following:

• Respiratory problems
• Chemical burns
• Long-term health effects including cancer

Chemicals that do not pose an immediate threat to human life may still cause extensive environmental damage and require expensive cleanup. Potential environmental effects include the following:

• Contamination of surface water and ground water resources
• Contamination of drinking water
• Destruction of sensitive environmental resources, including fish and waterfowl

These spills may also violate state and Federal laws, and may result in fines and penalties.

Causes

A variety of causes were associated with chemical transfer spills. The following were the most common root causes:

• Personnel errors
• Design defects
• Procedural inadequacies
• Inadequate administrative controls
• Defective materials or parts

The distribution of root causes is shown in Figure 5.

Personnel Errors

The most frequent cause of chemical transfer spills was inattention to detail, including the following.

• Attention lapses
• Leaving valves open
• Failure to close an isolation valve
• Not tightening a pipe cap
• Opening the drain line instead of the fill line
• Improperly seating a quick-disconnect hose
• Aligning a pump backwards and drawing from the tank that was supposed to be filled

Closely tied to inattention is the failure to follow procedures: for example, failure to monitor tank conditions as required.

Figure 5. Distribution of Root Causes of Chemical Transfer Spills

Design Defects

Lack of level indicators, improperly designed level indicators, and lack of an independent method of checking tank and tanker levels led to some spills. Several spills were caused by improperly sized or designed vents. The lack of check valves and valve position indicators also resulted in releases. Lack of a method to verify depressurization was also given as a cause of spills. Other design defects that led to spills included inadequate seal, manometer, and road designs.

Procedural Inadequacies

Some causes of spills involved omission of procedural steps to verify that valves were closed and lack of requirements to inspect system valve positions before and after transfer. Operators must ensure the integrity of the entire system they are connecting to, not just the connection between the tanker and the fixed tank. Procedure problems leading to spills included omission of the following:

• Sufficient time for complete depressurization
• Draining of liquid in piping to its source
• A catch pan under a connection
• Taping connections

Other problems included use of an incorrect procedure and failure to observe Department of Transportation requirements.

Inadequate Administrative Controls

In some cases, management was not involved in planning, and there was inadequate inspection and lack of training. Poor communication of spill policy to vendors and failure to provide safety information to managers were also mentioned as causes.

Defective Materials or Parts

The following items were found to cause some spills:

• Seals
• Hose clamps
• Fittings
• Door latches
• Fill level indicators
• Pump diaphragms

Loose flange bolts, corrosion of a tanker wall, and inadequate diking were also listed as causes.

Corrective Actions

NFS recommends the following practices to minimize the number of chemical transfer spills:

Design Issues

Several design issues required corrective actions, such as tank vent design and sizing. Vents must allow filling at the largest anticipated rate without overflowing. When possible, equipment should be designed to catch overflows before they are released to the environment.

Check valves should be installed to prevent backflows from the tank to the tank truck and to prevent the occurrence of other unintended flows. Equipment for measuring the level of liquids in both fixed tanks and tanker trucks should be provided. Valve positions should be indicated.

It is also important to clearly label pumps, connections, and switches and to provide necessary information about temperature, pressure, flow rate and direction, and chemical compatibility. Labeling should identify the chemical stored in tanks. Incorrect identification can allow incompatible chemicals to be mixed.

Finally, transfer systems must always be designed for the pressures, temperatures, and reactivity of the chemicals transferred. In the case of flammable materials, provision must be made for grounding the tanker and the tank to prevent sparks.

Maintenance and Testing

Equipment used in chemical transfer operations must be kept clean and in good condition. Tanker trucks, hoses and other equipment must be cleaned between uses for different chemicals to prevent contamination.

Equipment must be maintained, tested, and periodically calibrated to ensure proper operational availability. A systematic approach in maintenance and test programs is required to achieve reliability goals. This should include planned replacement of equipment to prevent aging failures and the use of proven methods.

Maintenance and testing should not compromise safety features or introduce unsafe conditions. It should enhance performance and maximize equipment service life. Maintenance and testing should be scheduled and performed in accordance with written procedures. Results should be documented and should include the following information:

• Date and time
• Modules and equipment
• Procedure used
• Test input values
• Verification that the system was returned to its normal, operable state
• Failures detected from testing and corrective actions
• Signatures of personnel according to established protocols

It is also important to repair damaged equipment promptly. At least one spill occurred because damaged equipment was not repaired when the problem first occurred and was left in a condition to malfunction again.

Management Issues

The most important management function relating to chemical spills is subcontractor control. In many cases, the spill of a chemical at a DOE site can be traced to vendors. DOE and management and operations contractors should train vendors on site delivery requirements and procedures and hold them accountable for spills caused by their employees or equipment. Vendors who cannot meet adequate safety standards should be replaced. This policy must be communicated to the vendors.

Training

Personnel responsible for receiving or transferring chemicals should be trained on the equipment they use. Because of the possibility of spills, they should also be trained in emergency spill containment.

Planning Issues

Chemical transfers should be conducted in accordance with either an approved procedure or a work plan. A hazard analysis or task analysis should be performed to identify risks in transfer operations, problems in design of the transfer system, and weaknesses in the procedure or work plan.

Steps for the following requirements should be included in procedures

• Ensure that equipment is compatible with the chemical being transferred and is designed for temperature and pressure of the chemical.
• Verify that the tanker truck is connected to the proper tank to prevent accidental mixing of incompatible chemicals.
• Ground the tanker and tank before the transfer to prevent sparks when handling flammable chemicals.
• Specify personal protective equipment.
• Inspect transfer equipment visually before the transfer starts.
• Verify valve positions and appropriate levels before the transfer begins.
• Monitor pressures, fill rates, levels, and valve positions during the transfer.
• Purge transfer lines before they are disconnected.
• Ensure that valves are returned to the proper position when transfer is finished.

Industry Practice

The chemical industry has extensive experience in handling chemicals and several helpful publications are available.^{8, 9, 10, 11}

The Code of Federal Regulations gives some guidance on transfer of chemicals. A qualified person must be in attendance at all times when tanks are being loaded and unloaded. To qualify, a tanker driver must be aware of the nature of the chemical, have emergency procedures training, and have the authority and means to move the truck if required. Other provisions apply to various classes of chemicals. Guidance is available in 49 CFR 177¹² for chemical transfers. DOE 5400.4¹³ provides guidance for responding to releases of hazardous substances in compliance with the Comprehensive Environmental Response, Compensation, and Liability Act.

References

1. DOE-STD-7501-95, Development of DOE Lessons Learned Programs.
2. Emergency Response Manual for NFPA 472, chapter 6, "B-Level Specialist Employees."
3. DOE Final Occurrence Report SR--WSRC-REACK-1991-0030, "Diesel Fuel Oil Spill," November 5, 1992.
4. DOE Final Occurrence Report ID--EGG-ADMPROC-1993-0003, "Burner Fuel Spill," July 17, 1995.
5. DOE Latest Update Occurrence Report RFO--EGGR-ENVOPS- 1995-0017, "#1153/Hydrochloric Acid Released to Secondary Containment," January 11, 1996.
6. DOE Final Occurrence Report ID--LITC-ATR-1995-0025, "Concentrated Sulfuric Acid Spill to Environment While Unloading Acid Truck In The Test Reactor Area (TRA) Utility Area," October 13, 1995.
7. DOE Initial Update Report ID-LITC-ERP-1995-0025, "Propane Release at Mercury Retort Operations," January 4, 1996.
8. Guidelines for Storage and Handling of Reactive Materials, G30, Center for Chemical Process Safety, New York, 1995.
9. Guidelines for Chemical Transportation Risk Analysis, G28, Center for Chemical Process Safety, New York, 1995.
10. Guide to Process Safety, Synthetic Organic Chemical Manufacturers Association, 1995.
11. Distribution Code - Resource Manual, Chemical Manufacturers Association, 1995.
12. 49 CFR 177, subpart B, "Loading and Unloading."
13. DOE 5400.4, Comprehensive Environmental Response, Compensation, and Liability Act Requirements.

Safety Notices Issued

• Technical Notice 94-01, "Guidelines For Valves in Tritium Service," September 1994.
• Safety Notice 91-1, "Criticality Safety Moderator Hazards," September 1991.
• Safety Notice 92-1, "Criticality Safety Hazards Associated With Large Vessels," February 1992.
• Safety Notice 92-2, "Radiation Streaming at Hot Cells," August 1992.
• Safety Notice 92-3, "Explosion Hazards of Uranium-Zirconium Alloys," August 1992.
• Safety Notice 92-4, "Facility Logs and Records," September 1992.
• Safety Notice 92-5, "Discharge of Fire Water Into a Critical Mass Lab," October 1992.
• Safety Notice 92-6, "Estimated Critical Positions (ECPs)," November 1992.
• Safety Notice 93-1, "Fire, Explosion, and High-Pressure Hazards Associated with Drums and Containers," February 1993.
• Safety Notice 93-02, "Control of Temporary Modifications," September 1993.
• Safety Notice 94-01, "Contamination of Emergency Diesel Generator Fuel Supplies," July 1994.
• Safety Notice 94-02, "High-Efficiency Particulate Air Filters," August 1994.
• Safety Notice 94-03, "Events Involving Undetected Spread of Contamination," September 1994.
• Safety Notice 94-04, "Uninterruptible Power Supplies," November 1994.
• Safety Notice 95-01, "Decision Analysis Techniques," August 1995.
• Safety Notice 95-02, "Independent Verification and Self- Checking," September 1995.
• Safety Notice 95-03, "Lessons Learned Programs," October 1995.
• Safety Notice 95-04, "Post-Maintenance Test Programs," December 1995.
• Safety Notice 95-05, "Department of Transportation Non- Conformances by Vendor Shippers," December 1995.