Following Proper Procedures For Equipment Use In Unloading Will Improve Crude-By-Rail Safety For All High Profile Events Have Raised Questions About Crude-By-Rail Shipping.
Midland warns that railcar equipment and components, such as Vacuum Relief Valves, that are used on crude-oil railcars will only perform to expectations if proper operational procedures are observed and used.
The safety and viability of crude-by-rail shipping has been a constant topic in the news on a seemingly daily basis over the past several months, triggered by the tragic events that occurred in Lac Mégantic, Quebec, last July, and continuing with a number of high-profile incidents that have made headlines throughout North America.
As a manufacturer, one area we need to stress—while not being linked to the recent safety concerns—is the need for the proper loading of crude railcars, which, if done improperly and against industry best practices, can result in service interruptions and damage to valves and fittings.
Vacuum Relief Valves (VRVs), as defined by the Association of American Railroads (AAR) in its “M-1002 Specifications for Tank Cars,” are “[a] pressure-relief device designed to admit air to prevent an excessive internal vacuum and to reclose after normal operating conditions have been restored.” VRVs have been used for decades to protect the tank itself from imploding—i.e. a catastrophic failure—as vapors escape from the tank, especially during cleaning operations. VRVs are a relatively inexpensive way to protect an expensive and critical asset.
With the rapid rise in crude-by-rail traffic in recent years, there are many new players entering the marketplace that are unloading tank cars filled with crude oil. When a non-pressure general purpose car is unloaded, the AAR recommends* “using a vapor-recovery system (Sec. 2.1.15)” and specifically states that “VRVs should not be used to vent pressure (Sec. 3.1.63).”
Properly classifying and securing loaded railcars for shipment is critical to safety, but unloading cars without venting them properly (possibly in order to speed unloading or to prevent vapors from escaping during the venting process) is critical to safety, as well. By not venting railcars properly (Pamphlet 34 recommends manways and vent valves to be installed at this critical relief point), the VRV can be throttled and held open for potentially hours, an operation for which it was not designed. When this happens, the constant pressure on the device can pull contaminants, solids and other debris into the seating area, causing damage (especially corrosion) and compromising the VRV’s ability to seal off the device properly. A consequence of this is VRVs that cannot seal can typically lead to Non-Accidental Release (NARs) incidents, for which the shipper of record can be held liable for damages with the potential for severe financial penalties.
Stainless steel and enhanced design versions of VRVs, such as Midland’s A-212 Series, incorporate a fine-mesh filter on the external portion of the valve, which can prevent and limit debris and contaminants from entering the body of the valve. However, nothing can prevent these issues better than following well-established, tried-and-true unloading procedures that have been proven to be both safe and effective when servicing crude-by-rail railcars.
In the railroad industry, Midland and railcar manufacturers are united in their desire to make crude-by-rail shipping as safe as possible for personnel, communities and the environment.
Questions? Ask an expert. Call Midland.
* Source: AAR’s CPC 1232 – Pamphlet 34, Recommended Methods for the Safe Loading and Unloading of Non-Pressure (General Service) and Pressure Tank Cars.