Chlorine railcar “enhanced fittings”

What do they mean to hazmat responders?

CarolinaFireJournal - Glenn Clapp
Glenn Clapp CHMM, CFPS
10/18/2009 -

Imagine that you are a hazmat team member responding to a product leak from a chlorine railcar in your jurisdiction. Upon arrival of your team, you begin to “work” the incident in a traditional manner. The leaking railcar is identified. The product is confirmed to be chlorine. PPE compatibility is checked. Decontamination is set up. A Recon Group suits up to make an entry. A Back-Up Group suits up to stand by. The ICS structure is established. As a member of the Recon Group, you perform air monitoring en route to the railcar and notice that the leak appears to be emanating from the protective housing. 


You and your fellow Recon Group member then climb the access ladder to take a look. When you open the protective housing cover, you observe three angle valves and one pressure relief valve inside the housing. The housing appears to be larger than the standard chlorine protective housing and has four tubular bars mounted inside it. As you scratch your head (most likely in a figurative sense, as you are in Level A chemical protective clothing and are atop a railcar), you remember the statement from Hazmat Technician Class that all chlorine railcar protective housings are alike. What are you actually dealing with?

The preceding scenario could happen in the real world. What you are dealing with is actually a chlorine railcar with an “enhanced fittings” or “next generation fittings” package (part of the Next Generation Railroad Tank Car [NGRTC] program). Currently 25 such railcars are in trial use in the United States. Although the enhanced fittings packages should dramatically reduce the number of chlorine product releases from pressure railcars due to numerous design improvements, hazmat responders need to be cognizant of the differing techniques required to mitigate leaks from these upgraded railcars as compared to their standard chlorine brethren.

Chlorine railcars with the enhanced fittings packages should be relatively easy to spot. The protective housing exhibits a lower profile than standard protective housings and is also larger in diameter (similar to an LPG or 20” style protective housing). In addition, railcars with the enhanced fittings packages in service trial use will be marked on the exterior with a stencil denoting “ST-422” and will also contain a decal inside the protective housing indicating the existence of the enhanced fittings. In terms of the physical arrangement of the fittings, hazmat personnel will note one pressure relief valve and three angle valves. Four bars are also fitted to the housing to accommodate both Chlorine Type C and Midland Emergency Response Kits.

The departures from the standard chlorine railcar fittings inherent in the enhanced fittings packages are designed with safety foremost in mind. The primary seals on the angle valves and the pressure relief valve (PRV) are all located underneath the surface of the pressure plate to reduce the chances of a release of product, even following a shearing off of the protective housing itself. The rupture disc of the PRV is located in the pressure plate, and the primary seals of the angle valves are actually check valves (located beneath the pressure plate) that are actuated by the stem of the valve itself.

An additional visual departure is that the angle valves are of the descending stem type, in that the handwheel is at its lowest point when in the open position to allow the check valve to be opened. The handwheels are still turned clockwise to close and counterclockwise to open.

What do all of these introductory facts mean to us as hazmat technicians when we are trying to apply a kit to stop a leak? First of all, the four tubular bars mounted inside the protective housing allow for the application of two emergency response kits (i.e. a Midland Kit and a Chlorine C Kit) simultaneously (yes, that would constitute a very bad day) and also allow the kits to be applied with the attachment assemblies at the optimum position. In addition, the bars also enable the Chlorine C Kit to be applied with a minimum of difficulty due to the increased diameter of the housing itself.

If your team will be using a Chlorine C Kit to mitigate the leak, there are a few points to keep in mind. Either the aforementioned bars or the usual sidewall ports in the protective housing may be utilized as anchor points for the kit, however, only one kit may be applied if the ports are used. To use the sidewall ports, it is best to unbolt one of the hooks of the C Kit, secure both hooks in the ports, and then reattach the detached hook to the strongback. This technique is necessitated by the increased diameter of the housing compared to the industry standard. The primary change in technique, however, is the requirement that the can or bonnet used in capping the PRV (square base, #24 in the C Kit) be used to cap the liquid or vapor angle valves due to the increased size and updated shape of their new design. The angle valve handwheel may also have to be removed prior to application of the can, and the flange face plate present on the valve face may also need to be removed so as not to interfere with the bonnet itself (a threaded 1” pipe may be fabricated and kept with the appropriate emergency response kit to screw into the valve to assist in removing the flange face plate).

In the event that a Midland Kit is utilized to cap the leak, many of the same techniques used with the C Kit will still apply. You may use either the tubular bars or the sidewall ports for mounting the Kit, and angle valve handwheels and valve flange face plates may need to be removed prior to applying the Midland Kit. Capping any of the angle valves will also require the same can as used with the PRV (#4 in the Midland Kit) due to the size and shape of the valves. The chain and plug from an angle valve can be simply wrapped around the valve, rather than cutting the chain with a bolt cutter to improve access (the same holds true with the C Kit). Due to the safety features designed into the new enhanced fittings, chlorine railcars and the fact that only a relatively small number of such railcars are in trial use, it is unlikely that you will encounter a leak from an enhanced fittings railcar in the near future. The facts remain, however, that additional enhanced fittings railcars may be produced if the service trial yields favorable results and advanced knowledge of the design features of and techniques used in mitigating leaks from enhanced fittings railcars should be useful if by some stroke of luck you encounter such a leak in the field. In closing, remember that we are all in the hazmat community together-if you learn something useful in hazmat, pass it on to another responder. And most importantly, stay safe out there.

Glenn Clapp is President of the North Carolina Association of Hazardous Materials Responders and is a Fire Training Commander (Special Operations) for the High Point Fire Department. He is a Technician-Level Hazmat Instructor, a Law Enforcement Hazmat Instructor, and is a Certified Hazardous Materials Manager and Certified Fire Protection Specialist. He holds a Bachelor of Science Degree in Fire and Safety Engineering Technology and a Master of Science Degree in Occupational Safety.
Comments & Ratings

  11/30/2012 10:08:04 AM
Cal Chem 

Rain Tank Car Safety 
WARNING: FIRST RESPONDERS’ use of THE CHLORINE INSTITUTE “C” KIT may cause the catastrophic failure of a chlorine tank car, instantly creating a toxic gas plume with a distance of not less than seven miles. The first mile will have chlorine concentrations of 1,000 ppm, causing death after one or two breaths with no opportunity for escape. To learn more, see PETITION C KIT, click on “First Responder Warnings.”New Comment
  9/24/2012 3:58:48 PM

New Comment 
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  8/1/2012 10:16:04 AM
Petition C-Kit 

Petition C-Kit 
First Responders and Haz Mat Experts petition Dow Chemical Company for safe rail tank cars transporting gas chlorine. Secondary containment is a necessary improvement that must be implemented.

See-- PETITION C KIT for First Responder and Haz Mat Expert comments.

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