Friday, July 12, 2013

PHMSA Safety Guidance – Heating Railcars for Bulk Transfer

Today the Pipeline and Hazardous Material Safety Administration (PHMSA) published a Safety Advisory Guidance document in the Federal Register (78 FR 41853-41856) concerning the heating of bulk chemicals in rail cars for the purpose of unloading or transloading those materials. PHMSA is taking this action in “coordination with the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA), and in consultation with the Federal Railroad Administration (FRA)”.


The document starts out with background information describing the nature of the problem that PHMSA is trying to prevent. Two specific instances of catastrophic failures of rail cars being heated to enable the material to be off-loaded are described in the background portion of the document:

• A 1999 incident in Clymers, In. at the Essroc Cement Corporation (Essroc) Logansport cement plant; and
• A 2002 incident in Freeport, TX at the BASF Corporation chemical facility

The both incidents were caused by excessive heat from a chemical reaction exotherms; due to a self-reaction incident in the first case and a self-accelerating decomposition reaction in the second incident.

As a result of their investigation of the second incident, the National Transportation Safety Board (NTSB) made the following recommendation to the predecessor to the current PHMSA organization, the Research and Special Programs Administration:

In cooperation with the Occupational Safety and Health Administration and the Environmental Protection Agency, develop regulations that require safe operating procedures to be established before hazardous materials are heated in a railroad tank car for unloading; at a minimum, the procedures should include the monitoring of internal tank pressure and cargo temperature. (R-04-10)


PHMSA maintains that the current regulations administered by itself {49 CFR 171.1(b) and (c)),  49 CFR 171.8, 49 CFR 172.700, and 49 CFR 174.67}, EPA {40 CFR Part 68, 40 CFR Part 112, and  40 CFR 68.130}, OSHA {29 CFR 1910.119, 29 CFR 1910.106(f), and 29 CFR 1910.120 } and the FRA already adequately regulate this activity. Having made that clear, PHMSA allows that “ it is always beneficial to remind regulated entities of their duties in affecting safe transportation and to offer guidance in furtherance of performing these duties”.

With that in mind, PHMSA states that:

“PHMSA, in coordination with OSHA and EPA, and in consultation with FRA, is issuing this safety advisory guidance to offer guidance on heating of a rail tank car to prepare solidified or viscous hazardous material products contained in the rail tank car for unloading or transloading. Based on existing regulatory requirements, we have assembled and coordinated the following guidance toraise awareness of those requirements and the risks associated with heating rail tank cars. This guidance does not include all of the aspects applicable to the safe heating of rail tanks cars; rather, it focuses on the issues raised in the NTSB recommendations as a result of its investigations into the two incidents cited above.”


The guidance document goes on to suggest (not require) that each shipper or facility operator develop a written procedure for heating hazardous materials in a rail tank car for unloading or transloading. Those “procedures should [emphasis added], at a minimum, establish hazard controls necessary to protect workers, the public, and the environment from adverse consequences”.

The suggested procedures should include:

Detailed information regarding the chemical characteristics of the material;
The pressure created by heating the rail tank car;
Active monitoring and recordkeeping requirements of the internal tank pressure and material temperature during the heating process;
Potential consequences of deviations from standard operating procedures and how to identify, control and respond to those consequences; and
Training of all entities involved in the unloading or transloading process.

The monitoring requirements come in for additional comment in the document. Reactive chemistry is briefly addressed:

“Certain chemicals, such as a material that can undergo rapid exothermic decomposition, may require more frequent or even continuous monitoring during heating. Monitoring of the tank pressure and the temperature of the hazardous material includes measures to ensure that the heating rate does not result in over pressurization of the rail tank car.”

Training also receives special attention. The document notes that the employee (Designated Employee) responsible for heating and monitoring the rail car should be “made thoroughly knowledgeable of the nature and properties of the material contained in the rail tank car and procedures to be followed in the event of an emergency”. It also explains that the designated employee “should have the ability and authority to take responsive action”.

Commentary - Missing Information

Having been a principle in a number of process hazard analysis’ (PHAs) and hazard assessments (HAs) in chemical facilities where self-reactive materials were a major component of the products we made, and having been responsible for two specific processes where we knew that self-accelerating decomposition reactions (SADR) were possible at process attainable temperatures I appreciate what PHMSA has attempted to produce here, but there are some serious shortcomings in the guidance.

Some things that are not covered include:

Discussion of pressure relief devices. Rail cars are typically equipped with simple pressure relief valve (PRV), but those are not designed to handle the fast and very large increase in pressure associated with the heat produced by self-reactive chemicals or the heat and gas production of SADRs. The proper sizing of relief devices is a complex engineering discipline that most organizations cannot take care of in-house.

Discussion of responsibility for maintaining ‘vessel’. Facility operators do not normally own and maintain rail cars that deliver raw materials. Properly maintaining the seals, valves, and various devices on the railcar are an important part of maintaining their integrity during high-temperature and high-pressure situations.

Discussion of determining what types of information that may be necessary for determining the safe-heating parameters for the heating of self-reactive chemicals and chemicals with relatively low SADR temperatures. This may include ensuring that the inhibitor (chemical used to stop the self-reacting chemicals from self-reacting) is present in the proper concentration, how to stop the self-reaction process (SRP) once started (most SRPs will be exothermic), and the initiation temperature of SADRs (otherwise fondly known as the ‘Oops too late’ temperature. (NOTE: This is at the heart of the problem identified by the Chemical Safety Board with both the EPA’s and OSHA’s chemical safety programs; this is not currently covered by either program.)

Discussion of what types of emergency planning might be necessary. Current emergency planning rules do not include the explosive consequences of vessel failures from self-reactive processes or SADRs (again at the heart of the CSB complaint). Where such blasts are a realistic possibility such planning needs to include blast walls, fire suppression systems, personnel protective areas, etc.

I can hardly fault PHMSA for not including the above discussions; they fall well outside their typical areas of expertise. Their partners in this program have been ignoring these factors for about ten years now, so it is hardly surprising that they did not provide better guidance to the lead agency on these topics.

It will be interesting to see if the NTSB or the Chemical Safety Board weigh in on the inadequacies of this guidance. The NTSB will probably be satisfied as it is also outside their primary area of expertise. It is more likely that the CSB will take objection to the inadequate coverage provided in the guidance, but they are already fighting a couple of major bureaucratic battles and may be unwilling to take on another.

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