DESERT FIRES AND RAIL IMPACT TESTING – MAKING HYDROGEN TRANSPORTATION SAFE
FIBA Technologies has been at the forefront of decades’ worth of research, design and testing to produce the safe methods of hydrogen transportation and storage we rely on today. Often working with the CGA (Compressed Gas Association) and other key players in the industry, FIBA has contributed to major improvements in gas transportation safety.
Here’s a brief look at of just some of that work.
In 2001 in Ramona, Oklahoma, a 10-tube Jumbo trailer crashed and its tubes became detached from the chassis which led to a gas leak and a fatality. Following this tragedy, the National Transportation Safety Board pushed for a reassessment of the way compressed gas tube trailers were designed because the trailer involved had insufficient structural integrity.
The industry worked with the CGA to develop a new Standard for design requirements for tube trailers and tube modules. Standard C29 (formerly TB-25) is now incorporated into the DOT Code of Federal Regulations CFR 49.
Part of the work to develop that new standard involved a series of rail impact tests (Fig 1). This was seen as the best way to duplicate longitudinal loads experienced by tube trailers during handling and transportation. Of the various types of trailer designs tested, results showed that the modular design gave far higher levels of protection as it held the tubes firm throughout.
FIBA’s Safer Modular Trailer
On hundreds of conventional trailers deployed the stress of the connections attaching the tubes could greatly exceed code-required levels. FIBA designed the trailer to relieve the stress points, reducing the risk of the tubes being dislodged during a crash.
The graphic below shows favourable finite element analysis (FEA) results once the structure support had been developed, with stress distributed more uniformly.
As we have seen elsewhere, FIBA’s patented modular trailer design continues to help precent impact leaks when gas trailers endure a collision. It better withstands impact and prevents leaks if a truck is involved in a collision.
So successful is this design that now, when FIBA re-tests and re-builds trailers, they are upgraded to incorporate this modular design. This also has the benefit of extending their retest cycle from five years to 10.
Responding to the Ramona Incident, where eight of the 10 valves sheared off on impact, special shear off valves developed by FIBA and valve manufacturers Sherwood are also now deployed on these trailers.
A further major step in enhancing trailer safety came after a fire test staged in the Mojave Desert. The Mojave fire tests saw FIBA, the CGA and other parties engulf a trailer in jet fuel flames up to a temperature of 2,000°F for more than 20 minutes. The aim was to check if the tubes remained intact long enough for emergency responders to reach the scene (~ 20 minutes); check whether the tubes would burst during the test; and to see if and how the fire might affect the pressure containment capability of the tubes.
Measurements showed that the pressure dropped steadily during the test, negating the notion that tubes without a pressure relief device would simply burst into flames. This meant that with a normal cylinder valve orifice, and the use of plastic seats, the gas could escape while the pressure fell steadily and safely.
This led industry regulators to allow the safe removal (where appropriate) of pressure relief devices on Type 1 hydrogen trailers. The fire test also demonstrated that the tubes remained intact for up to 30 minutes; that they did not burst during the test; and that the tubes’ strength remained adequate.
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