Sealing Shielding

Why Non-Accident Releases (NAR's) are Increasing

why the sudden increase in non accident releases (NARs), manway gasket, crude oil, railcar, gasket, railwaysFollowing four consecutive years of decreasing NAR's, 2014 has significantly bucked the trend with current estimates reverting back to 2011 levels. Since 2009, hazardous shipments by rail have increased 42%, yet as noted in a previous Parker blog, the number of FRA and PHSMA inspectors has remained relatively flat.

The latest figures published by the Association of American Railroads (AAR) for the previous year ending June 30th, 2014, do not paint a pretty picture. Unfortunately, comparative figures for the same period the prior year were never published. What is clear, however, is that all forecasts for 2014 have been grossly underestimated.

In 2013, a total of 535 NAR's were reported. The projected total for 2014 is 634, representing a 19% increase.


nonpressure car NARs by component, Why non accident releases are increasing, crude oil, rail, railways, railcars


Crude Oil Shipments Struggling the Most

The highest offending commodities related to NAR's are Crude Oil and Alcohol NOS. Of particular concern is the continued growth in crude oil shipments, which are projected to top over 600,000 carloads in 2014.

crude oil, non accident releases, NARs, manway gasket, railcar, gasket, railwaysalcohol NOS, non accident releases, NARs, manway gasket, railway, railcar, gasket

With exponential growth comes growing pains, one of which being inexperienced staff or high turnover of staff. What is unquestioned is that, what is currently considered standard best practices/ equipment is not quite as good as it needs to be. Even for those shippers that are not experiencing NAR's, what is the cost of ensuring this continues? How long does it take to load and secure a car? How much are you paying to do so?

Same Problem – Same Answers

The manway continues to be the biggest culprit when it comes to NAR's. The same four issues remain unresolved. For all the ‘innovations’, gasket materials, lid & bevel designs, the industry seems incapable of demonstrating any improvements. Consistently ranked as the No. 1 issue industry-wide, loose manway bolts account for 53% of all manway NAR's and 61% when analyzing crude oil shipments separately.


crude oil, non accident releases, railcars, railways, manway gasket, NARs, gasketnonpressure cars, non accident releases, NARs, manway gasket, crude oil, railcars, railways, gasket


Simple Physics – Why Is No One Asking Themselves

When it comes to NAR's, the manway and the bottom outlet cap represent two of the three predominant issues. In the case of the bottom outlet cap, it should come as no surprise to learn that the reasons for its failure are identical to what afflicts manways.

In both cases the No. 1 issue is loose bolts/ cap. In order for a bolt or threaded cap to maintain its torque, it has to stretch to a predetermined preload. In addition to achieving this required stretch, the torque must be maintained.

The problem arises when seals/ gaskets are incorporated as they are in both the manway and bottom outlet cap. Whether using a soft elastomeric or hard PTFE gasket, the seal will either compress or creep, which invariably relaxes the stretch. Once the stretch is relaxed, the bolt/ cap is free to work itself free, something that is exacerbated with motion and vibration.

Why Current Gasket Options Only Partially Work

Ironically it should be stated that the industry does not have a sealing issue. Whether using an elastomeric or hard gasket, both work adequately well at providing a seal. However, current gasket options require great care when installing and removing. Oftentimes, bolts tend to be over-torqued causing the manways to come out flat or round, resulting in costly repairs. The gaskets that are currently being used present some limitations which include:

  • No gasket guarantees more than one use
  • No gasket guarantees against loss of bolt torque
  • No gasket is designed to alleviate the major causes of NAR's
  • No gasket is designed to reduce labor costs and incidence of injuries

The Only Proven Solution

Established practices, especially those that have been diligently learnt through trial and error can be difficult to change. Just because a solution exists, does not mean it is the best solution.

In the case of manways, industry best practices are only as good as the equipment and tools available. That is why the Parker Manway Nozzle Gasket is one response to halt this growing trend of NAR's. Not only does it immediately resolve 95% of all manway related NAR issues, which is approximately 50% of all NAR's, it also reduces loading times and costs by as much as 90%.


For more information, please visit Parker Integrated Sealing Systems Division.


*All graphs and data provided by the Association of American Railroads and AAR/BOE Hazardous Materials Release Reporter Database & Annual Hazmat Reports.


Emanuel Guerreiro, Parker Hannifin Corporation, Integrated Sealing Systems Division, Industiral Market Development Manager



This article contributed by Emanuel Guerreiro, Industrial Market Development Manager, Parker Hannifin Integrated Sealing Systems Division.




For related content, see the below links.

Non-Accidental Releases (NAR's) in Railroad Tank Cars

NAR's: How to Reduce Cost of Railway Shipping

NAR's: Where the Feds Are Focusing

Why 95% of Manway Nozzle Gaskets Fail

Have a question about Parker products or services? We can help: Contact Us!

Comments for Why Non-Accident Releases (NAR's) are Increasing

Please note that, in an effort to combat spam, comments with hyperlinks will not be published.

Leave a comment