Matheson Gas Products-La Porte - Executive Summary
MATHESON GAS PRODUCTS - LA PORTE, TX BRANCH |
This Matheson Gas Products facility transfills and purifies compressed specialty industrial gases in cylinders in both large and small quantities. The source material gas which is transfilled and sometimes purified may be packaged in tube trailers, ton cylinder units or regular cylinders, depending on the gas. The finished product varies from a single pure chemical gas to gas mixtures, and the capacity of product cylinders varies from 2000 pounds to less than 1 pound of gas depending on the size of the cylinder and the type of material involved.
Matheson has identified four processes at this site containing greater-than-threshold amounts of chemicals subject to the RMP regulations: hydrogen chloride filling, phosgene filling, hydrogen sulfide storage and chlorine storage. For the hydrogen sulfide and chlorine, we have considered storage as an RMP "process". Because of the quantities involved, all four processes were assign
ed to Program 3.
We believe a large gas release from this facility is extremely unlikely. This facility has the equipment, the procedures and the training to ensure that a gas release impacting off-site areas will not occur. They are described in the Prevention Program section of this Executive Summary.
DESCRIPTION OF WORST-CASE AND ALTERNATIVE CASE SCENARIOS
In compliance with the USEPA definition of a worst-case scenario, the loss of the entire contents of the largest container over a period of ten minutes was modeled using RMPComp. Such a release is extremely unlikely since 1) it assumes catastrophic failure of a cylinder that is built to withstand pressure and temperature well above normal operating conditions; 2) it assumes the simultaneous failure of all safeguards; and 3) no allowance is made for the presence and use of active mitigation systems and procedures. Consequently this should not be considered a credible release situation.
-case release scenario at this location is for phosgene filling and assumes the loss of the largest container or 2,000 lbs. of gas in ten minutes, resulting in a theoretical off-site impact of 18 miles.
Alternative case scenarios
For phosgene filling and hydrogen chloride filling the alternative release scenario is a break or rupture in the filling line. Releases are most likely to occur during the filling process, and the most likely weak point in the filling process is the line or pipe used to convey the gas from the source cylinder or tube to the product cylinder.
For hydrogen sulfide storage the alternative release scenario is a valve leak. There is no real process occurring in storage; and the valve represents the only possible weak point of the cylinder in storage. For chlorine storage the alternative release scenario is a leak from the relief device located on the end of the ton unit.
Alternative release scenarios were modeled without considering any mitigating equipm
ent such as the scrubber, neutralizations system or containment units.
For hydrogen chloride filling, the alternative case release scenario assumes the loss of 50 lbs. over 5 minutes resulting in a theoretical off-site impact of 0.1 miles.
For phosgene filling, the alternative case release scenario assumes the loss of 1080 lbs. over 180 minutes, resulting in a theoretical off-site impact of 0.8 miles.
For hydrogen sulfide storage, the alternative case scenario assumes the loss of less than 1 lb. over 720 minutes, resulting in a theoretical off-site impact of less than 0.1 mile.
For chlorine storage, the alternative case scenario assumes the loss of less than 1 lb. over 720 minutes resulting in a theoretical off-site impact of less than 0.1 mile.
There has been only one accident in the last five years at this site involving RMP regulated processes. In 1997 the hydrogen chloride fill line ruptured, releasing less than one pound of liquid hydrogen chloride
instantaneously. There were no off-site impacts.
PREVENTION PROGRAM and EMERGENCY RESPONSE
There are numerous safeguards at this facility which make gas releases unlikely to occur and if they do occur, unlikely to leave the property. First and foremost is the construction of the cylinders themselves. The Department of Transportation (DOT) regulations, the National Fire Protection Association (NFPA) Codes and the Compressed Gas Association (CGA) guidelines mandate the way in which cylinders are manufactured and used. These standards were developed in order to virtually guarantee that cylinders would not fail even under extreme conditions during the rigors of shipping and use. Everything about cylinder construction is mandated, from the type of metallurgy to the wall thickness; every cylinder is designed to withstand pressure well above the fill pressure. In short every cylinder is designed to withstand extremes of operation and overpressure conditions that make either catastrophi
c or routine failure extremely unlikely; and each cylinder must be re-qualified to this standard every five years. In addition as with the cylinders themselves, any appurtenance such as pressure relief devices and valves must also meet similarly strict manufacturing standards which are so detailed that they mandate even the number and type of threads on the valve.
This facility is also equipped with mitigation equipment if a cylinder leak should occur. There are appropriate scrubbers to neutralize any fugitive emissions, and special emergency containment vessels and devices to completely contain a leak. Monitors and emergency shutoffs are also present.
Last but not least there are procedures in place at this facility to ensure leaks do not occur, or to mitigate a leak if it does occur. Cylinders are leak checked when they are first received and leak checked prior to being shipped out. Cylinder areas are routinely inspected. There are trained, experienced operators who have the
required knowledge, skills and abilities to safely carry out their responsibilities and are able to assess and resolve possible problems before they result in a release. The average years of service for operators on these processes is 9 years, and the senior operator has 16 years of experience.
The Emergency Response Plan at this facility includes notification of local agencies and medical providers. Employees have been trained and drilled in emergency response. There is an Emergency Response Team on site that has been trained in accordance with OSHA 29 CFR 1910.120 (Q)(6)(iii). They have access to the necessary equipment to quickly respond to an emergency release.
By September 30, 1999 the facility intends to upgrade the storage area for ton cylinder units so they will be completely isolated from all other plant activity. In addition an emergency shut-off will be installed for the phosgene filling area by July 31, 1999.