Air Liquide - Morrisville, PA. Plant - Executive Summary
The following details the prevention and emergency response plans and policies for the Air Liquide America Corporation and its Morrisville, PA. plant location. The worst case and alternate case scenarios for the Morrisville plant location are also detailed. |
AIR LIQUIDE - CORPORATE RESPONSE PLANS AND SAFTEY POLICIES
The Air Liquide Morrisville, PA. plant is part of Air Liquide America Corporation which has its headquarters in Houston, Texas.
Safety is Air Liquide's primary concern. Safety for its employees and safety for the chemicals it handles. The Air Liquide America Corporation is a member of the Chemical Manufacturers Association with a commitment to meet all the requirements of the Responsible Care Program. The corporation supports its own nationwide Emergency Response Program with trained responders strategically positioned in every part of the United States to respond to chemical emergencies. A national training center for this activity has been established by Air Liquide whe
re responders train to meet OSHA's HAZWOPER program requirements. In addition, Air Liquide has joined with other chemical companies with similiar chemical business operations in an emergency response mutual aid agreement. This mutual alliance enhances the capabilities of each member to better handle an emergency if additional resources are required. The corporation has also established annual safety goals with associated employee incentives when goals are achieved.
Air Liquide is a member of the Compressed Gas Association (CGA). CGA is an organization recognized worldwide for its primary mission of safety in the compressed gas industry. Several employees at the Morrisville plant are active participants in CGA committee work.
AIR LIQUIDE - MORRISVILLE , PA. PLANS AND POLICIES
The Air Liquide Morrisville plant adheres to the corporate safety policies and also has established their own local policies, programs, and procedures to ensure the highest level of safety is maintained within
The Air Liquide Morrisville, PA. plant primary activity is the filling of compressed gas cylinders with a variety of different gases. Some of these gases are very familiar to the public. For example, helium, carbon dioxide, and oxygen. The properties of the gases filled at the Morrisville plant range from nonreactive and non toxic to reactive and toxic. The compressed gases that fall under the RMP reporting requirements and are used at the Morrisville plant are chlorine, hydrogen chloride, and silane.
The Morrisville plant's primary activity is to fill product (compressed gases) from a bulk product source into compressed gas cylinders. This type of activity is commonly referred to as repackaging. Therefore the Morrisville plant activity is best described as a "repackager of compressed gases".
The Morrisville plant, like it corporate headquarters, fully supports the Responsbile Care Program and is active in all six codes of conduct which make up the program.
e Morrisville plant maintains its own emergency response team which is fully trained to handle an emergency with any of the chemical products on property. The team has a fully equipped emergency response trailer which is capable of going over the road to emergencies outside the plant. Any emergency situations on plant property are handled from the plant's Command Post Building. This building was specifically built to act as command center for plant emergencies. The command post is equipped with emergency equipment, product information, emergency contact phone list, and an independent phone line should the plant phone system go down or be inaccessible.
The Morrisville plant has an Off - Site Emergency Response Plan which is approved annually by the Local Emergency Planning Committee (LEPC). This plan details the essential actions to take should an emergency occur. This includes evacuation of the plant, notification procedures for emergency services and notification procedures for th
e surrounding public.
The Morrisville plant is also subject to the requirements of OHSA's Process Safety Management (PSM) Program which calls for Hazardous Communication training for each employee. Other key elements of the PSM Program which the Morrisville plant utilizes are Management of Change and Pre Startup Safety Review which assist plant management in monitoring the safety of a chemical process at the initial startup and throughout the lifetime of the process.
Morrisville management is an active member of the local Community Mutual Aid Committee. This organization is comprised of local chemical companies and emergency service groups in the area such as the LEPC , fire departments, hospitals, and first aid personnel. Through this organization dialogue between the operating chemical plants and emergency services is maintained. New chemicals and processes, changes in regulatory and code requirements, training sessions, table top and live practice scenario drills make up the agenda.
The committee meets approximately every 2 months.
The Morrisville plant has been ISO - 9002 certified since February, 1994. This is a certification of the quality system performed by an independent third party auditer twice a year. Key elements of this certification include documentation control (e.g., procedures), training, calibration of process equipment, and inspection and testing of product. These same requirements are also critical for chemical process safety making the ISO - 9002 a strong asset where training and control of a process are necessary elements.
The Morrisville plant is equipped with a 24 hour, 7 day a week security and fire detection system with links to local fire and police departments.
The Morrisville plant has had no reportable accidental releases for the last 5 years. Therefore no personnel injuries have been reported. In addition, the Morrisville plant has had no lost time injuries as defined by OSHA since the plant opened in 1990.
Every chemical produc
t that is processed or stored at the Morrisville plant has a Material Safety Data Sheet (MSDS) on file at the plant. Employee competency on product knowledge is accomplished through MSDS review, specific process training sessions, monthly safety meetings, and standard operating procedures. All of these elements are documented, controlled, and monitored as detailed previously per ISO 9002 requirements and the Hazardous Communication Program.
Standard operating procedures specify rigid leak testing and package preparation for all products. The primary concern for these steps is safety but the quality of the products must be of the highest level. The primary clientele for the Morrisville plant are electronics customers who use compressed gases in the process of making semiconductor chips. This application demands the purest raw materials be used in the process which includes the compressed gases. Very small leaks invisible to the naked eye or to standard leak testing techniques can be fou
nd prior to any introduction of product into a system or final package. This is accomplished by using sophisticated helium leak detection systems which have a far greater magnitude of sensitivity for finding leaks.
WORST CASE/ALTERNATE CASE SCENARIOS
The following are the worst case and alternate case scenarios that have been formulated for the Morrisville plant products that are subject to the RMP plan. There are three products addressed in this document; silane, hydrogen chloride, and chlorine.
SILANE - WORST CASE SCENARIO
Silane is a flammable gas which Morrisville receives as a bulk product source in an ISO container. An ISO container is very similiar to a standard gaseous tube trailer except that the container has the ability to be removed from its trailer chasis.This mobility allows this type of container to be placed on the deck of a ship for transportation overseas or be transported over land by railroad on a flatbed car. The Morrisville plant leaves the ISO container on i
ts trailer chasis while in use at the plant.
The ISO container consist of 12 high pressure carbon steel tubes interconnected with manifold piping. The tubes are approximately 20 feet long and have a diameter of 22 inches. There is a shutoff valve at each end of the tube. Each tube has its own safety relief devices at each end which activates due to a combination of excessive heat exposure and subsequent pressure buildup within the container. The manifold that interconnects the tubes has 2 main shutoff valves which can be used to withdraw product.These main manifold shutoff valves are pneumatically actuated and are defined as "normally closed" meaning that the valve will remain closed unless activated by pressure to its dome.
To determine the worst case scenario for silane Air Liquide conducted a hazardous operations analysis (HAZOP) on the silane system. The following was determinded to be the worst case scenario based on the experience and knowledge of the HAZOP team and the kno
wn history of silane in the compressed gas industry.
Each tube on the silane ISO container contains a maximum of 588 pounds of product. This product limit is based on the standard operating procedures and practices in place. The product supplied in the ISO container is weighed in and rechecked prior to shipment to Morrisville. Upon arrival to Morrisville, the container is check weighed again ensuring no overfill of product has occurred. During the use of the Iso container numerous visual inspections and leak checks are performed.
The conclusion reached by the HAZOP team is that the worst case scenario would be a complete failure of one of the tubes on the ISO container which would release the tube contents of 588 pounds. This complete failure would come from the mechnical failure of the tube.
The likelihood of this occurence was given the HAZOP rating description of "once in the lifetime of the plant or less than once in 100 years" which equates to virtually impossible. Given the
structural integrity of the tubes, the extensive inspections, leak checks and weight checks a tube receives during its normal lifetime, and the tubes exemplarily performance history in the compressed gas industry this HAZOP likelihood rating was a logical choice. Inspections includes a periodic 5 year requalification of each tube for structural integrity by a Department of Transportation certified testing facility. No tube has catastropically failed in silane service. Each tube has an individual shutoff valve which keeps them isolated from each other.
If a tube of silane released its entire contents the distance calculated for a 1PSI overpressurization is 0.66 miles. This calculation was derived from the equations provided in the RMP Offsite Consequence Analysis Manual for a worst case release of a flammable gas producing a 1PSI overpressure from a vapor cloud explosion.
SILANE - ALTERNATE SCENARIO
The determination of the alternate ("most likely") scenario for a silane release
was derived from the HAZOP analysis performed on the silane fill process by Air Liquide personnel at the Morrisville plant. A risk rating was assigned to each potential product release scenario. The risk rating is calculated from the combination of the likelihood of the scenario occurring and the severity of the scenario. The HAZOP analysis team was made up of members who have had extensive experience with silane and were well qualified to make these determinations.
The overall risk rating value was the primary factor in choosing an alternate scenario. Also considered when the risk rating was fairly equal for different scenarios was to choose the scenario with the largest potential release. This ensured that the largest affected zone was considered for emergency planning considerations.
Silane is not only a flammable but has the property of being pyrophoric (spontaneously combustible) . This means that upon contact with air silane burns with a visible flame. The combustion reacti
on produces silicon dioxide, a sand like dust material.
In all scenarios, both worst case and alternate cases, the release of silane does not go beyond the fence line of the Morrisville plant. This is due to the limited amount of silane that could be released and also silane's pyrophoric property as detailed in the previous paragraph.
The alternate scenario chosen for silane was a release from the main connection of the ISO container manifold. This type of release will produce a jet fire. The data used to determine the amount of the silane released and the endpoint came from the Compressed Gas Association Silane Study (release rate) and the Charm Modeling Program, Version 9.1 (endpoint) . These data sources were used to calculate the scenario because of silane's unique pyrophoric properties which limit the use of standard type formulas and assumptions. These calculations determined the entire tube (588 lbs.) would release through the main manifold connection given a mitigation
repsonse time of 10 minutes. The reponse time of 10 minutes is a very conservative number. The mitigation steps Morrisville has in place will significantly reduce the time to isolate the leak source and minimize the damage.
The worst case and alternate case scenarios result in the same amount of product release but the difference is in the hazard condition they produce. The leak from the trailer main manifold connection will produce a jet fire where the worst case scenario was a catostrophic failure of the trailer tube producing a vapor clould explosion.
The main manifold connection has a 1/2" tubing connected to it which feeds the supply of silane from the ISO container to the silane fill system. There were several other scenarios in the HAZOP analysis that were comparable in risk rating but this scenario offered the largest potential product release.
This silane release scenario will have several active mitigation measures in place to minimize the consequence of this release
. The ISO container is positioned under a fire detection/suppressant sprinkler system. Once a fire is detected the sprinkler system will activate and begin to spray the ISO container manifold and immediate area. The primary purpose of the sprinkler system is to protect the surrounding area from fire. Since Silane is pyrophoric it will continue to produce a flame as long as there is a leak.
The ISO container has 2 pneumatically controlled header valves. The operator can remotely shut down the silane product source by cutting the nitrogen supply off that keeps these valves open and therefore stop the flow of silane and the leak out of the manifold connection.
The nitrogen that activates the pneumatic valves is supplied through plastic tubing. The choice of this material over a metal type supply piping was intentional. Should a leak of silane occur the heat and flames produced can melt the plastic, cut off the supply of nitrogen and close the pneumatic valves, resulting in the isolation
of the product source.
In summary, any of the perceived alternate scenarios that could develop into a silane release can be managed by the Morrisville emergency response plans in place. Silane's pyrophoric property minimizes the dispersion distance.
HYDROGEN CHLORIDE - WORST CASE SCENARIO
Hydrogen chloride is a toxic product which is received at the Morrisville plant in tube trailers. Hydrogen Chloride is a liquefied gas under its own vapor pressure of 613 psig @ 70 degrees fahrenheit. The hydrogen chloride tube trailer consist of 6 tubes. Each tube is 40 feet long with a diameter of 24 inches. Each tube has a shutoff valve at each end and each tube incoporates a safety relief device at each end which is activated when the tube is exposed to elevated temepratures (165 degrees fahrenheit) and results in overpressurization of the tube. The 6 tubes are interconnected by a manifold and the manifold has a main shutoff valve where the connection is made to remove product. The trai
ler is filled with 20,000 pounds of hydrogen chloride. Each tube holds approximately 3300 pounds.
A HAZOP analysis was performed on the hydrogen chloride system. It was determined that the worst case scenario would be the mechanical failure of a tube. This release would have off site consequences. The distance that was calculated from a worst case scenario was 2.4 miles as determined from the RMP Comp Version 1.06 modeling program. The likelihood HAZOP description rating assigned was "once in a plant lifetime or less than once in 100 years" which equates to virtually impossible. This determination was based on the administrative controls in place, the structural integrity of the tubes, and historical performance of hydrogen chloride in tube trailers for the industry. Administrative controls include monitoring of product filled into the trailer by the supplier and the recheck of this product weight when received at the Morrisville plant. The product fill density, the amount of product
allowed in a container as determined by the Department of Transportation, is established at a value which allows for temperature exposures up to 130 degrees fahrenheit and for small errors in overfilling. The standard operating procedures in place call out for numerous visual and leak check inspections of the hydrogen chloride system (which includes the trailer)while on property and in use. In addition, each tube in the trailer must be requalified for structural integrity every 5 years by a Department of Transportation certified testing agency.
HYDROGEN CHLORIDE - ALTERNATE SCENARIO
The determination of the alternate ("most likely") scenario for a product release on the hydrogen chloride system was derived from the HAZOP analysis conducted on the process by Air Liquide , Morrisville, Pa. plant personnel.
The potential product release scenarios developed from the HAZOP were each assigned a risk rating factor. The risk rating is calculated from the combination of the likelihood of
the scenario occuring and the severity of the scenario. The HAZOP team personnel all had extensive experience with hydrogen chloride and were qualified to make these determinations.
The HAZOP produced several scenarios with comparable risk ratings. The scenario chosen was one that produced the most potential product release and would extent beyond the fence line of the Morrisville plant.
The alternate scenario chosen was the release of hydrogen chloride through a failed safety device on the end of one of the tubes of the hydrogen chloride trailer.
The release rate was calculated by Air Liquide's Research and Development department utilizing formulas specifically developed for the sudden release of a pressure vessel. The amount of release calculated for this scenario was 1300 pounds of hydrogen chloride. The endpoint was calculated at 0.5 miles using the RMP Comp Version 1.06 modeling program.The release duration was established at 30 minutes which was the estimated time needed t
o have the release under control. This endpoint will not encroach on any residential areas.
There are active and passive mitigation measures in place to minimize the amount of product released should this event occur.
In the event a release through a safety device would occur the remaining product in a tube can be transferred to another tube on the trailer or into empty containers. This action produces two results; 1) the product that could leak out is reduced and 2) the rapid transfer of product into another container produces a cooling effect on the leaking tube which in turn lowers the vapor pressure of the hydrogen chloride and the rate of leakage from the safety.
The hydrogen chloride scrubber can also assist in the process of emptying a tube with a leaking safety.
To reduce the travel of hydrogen chloride vapors pass the property fence line a water spray supplied from the plant hydrant system positioned over the leaking safety will be used to knock down a substantial amount
of the product release.
Hydrogen chloride is a liquefied compressed gas with a vapor pressure of 613 psig @ 70 degrees fahrenheit. A passive mitigation measure is that hydrogen chloride will cool down in the event of a substantial leak . This in turn lowers the vapor pressure of the hydrogen chloride and results in lowering the leak rate.
CHLORINE - WORST CASE SCENARIO
Chlorine is supplied to the Morrisville plant in containers commonly known in the compressed gas industry as a "ton container" because they contain 2000 pounds of chlorine product. Chlorine is a liquefied gas under its own vapor pressure of 85 psig @ 70 degrees fahrenheit. The ton container has a cylindrical shape and lays in the horizontal position. It is typically moved around with a fork truck. The ton is approximately 7 feet long and has diameter of 24 inches. This container style has been used for decades in industry for chlorine service. The container has two valves installed at one end - one for vapor w
ithdrawal and one for liquid withdrawal. It also has 6 safety devices - 3 at each end of the container which are temperature activated should the container be exposed to elevated temperatures (greater than 165 degrees fahrenheit).
The HAZOP analysis performed on the chlorine system determined the worst case scenario would be the mechanical failure of the ton container. This failure would result in the contents of the ton (2000 lbs.) being emptied in 10 minutes and have an endpoint of 0.9 miles as calculated from the RMP Comp Version 1.06 modeling program. The release distance would not encroach on any residential areas.
The HAZOP description rating assigned to this was "once in a plant lifetime or less than once 100 years" which equates to virtually impossible. The reasoning for this HAZOP likelihood rating was based on the administrative controls in place and the historical performance of the ton container in industry.
The chlorine system is completely housed in a process building
which is approximately 15,000 square feet. The building acts as a passive mitigation to contain a portion of the chlorine release . Based on the data and information contained in the RMP Offsite Consequences Analysis Manual the building will reduce the release rate down to 55% of its original calculated value of 2000 pounds to a value of 1100 pounds. Air Liquide agrees that this number is the minimum reduction the building enclosure will provide. This value was incorporated in the equation for calculating the endpoint for the worst case scenario.
The chlorine ton containers are visually checked, leak checked , and product weight checked during and after fill by the supplier. The product fill density, the amount of product that can be put into a container as determined by the Department of Transportation, has been set at a value which allows for container temperature exposures up to 130 degrees fahrenheit and for small amounts of accidental overfilling.
When chlorine containers are
received at the Morrisville plant the same inspections the supplier has perfromed are repeated. In addition, the ton container must be requalified every 5 years by a Department of Transportation certified testing facility to verify its structural integrity.
CHLORINE - ALTERNATE CASE SCENARIO
The determination of the alternate ("most likely") scenario for a chlorine release was derived from the HAZOP analysis performed on the chlorine fill process by Air Liquide personnel at the Morrisville plant. A risk rating was assigned to each potential product release scenario. The risk rating is calculated from the combination of the likelihood of the scenario occurring and the severity of the scenario.
The risk rating value was the primary factor in choosing an alternate scenario. In the case of the chlorine fill process several scenarios had the same risk rating value. The scenario chosen was the one that produced the greatest product release.
The alternate scenario chosen for chlorin
e was product release through one of the six safety devices on the ton container. This would release 525 pounds of chlorine and have an endpoint of 0.1 miles. This endpoint will not encroach on any residential areas. The amount of the release is based on a 30 minute response time needed to mitigate the leak.
The active and passive mitigation measures are as follows.
In the event a leak should develop at the safety device the safety can be capped using the emergency repsonse kit specifically designed for this type of container. The kit is called a "Chlorine B Kit" and is manufactured by the Chlorine Institute of America. Once capped, the container can then be drained of all product and the safety replaced.
The contents of the container can also be sent to the scrubber or to another container which will lower the vapor pressure of the chlorine and slow the leak rate substantially.
Passive mitigation is the fact that the chlorine fill system is contained within a 15,000 square foot b
uilding. This natural barrier will reduce the escape of gas down to at least 55% of its orignal release rate. This value is sourced from the RMP Offsite Consequence Analysis Manual and Air Liquide has incorporated this into the calculations for determining an endpoint.