NTSB wants all tanks in a blanket

Good Friday, when most government workers were already off for their Easter/Passover long weekend, the National Transportation Safety Board warned that none of the tank car standards currently under consideration are adequate in the light of four recent oil train explosions involving the most modern cars on the rails.

In the sort of holiday-eve announcement normally intended to evade media attention, the NTSB issued a critical assessment of tank car proposals under final review by the White House. In this case, the unusual timing may be because of the overriding urgency to scuttle the merely incremental improvements to the current CPC-1232 tank car design. The White House Office of Management and Budget is expected to announce final rules for oil train reform sometime in May.

Each of the tank car specs under OMB consideration includes thermal protection equal to that now required for DOT-112 and DOT-114 tank cars carrying Class 2 flammable compressed gases, without specifying a particular fire-resistant construction. Instead, said the NTSB, new specifications should demand that tank cars exceed the so-called 49 CFR 178.18 performance standard by being wrapped in fire-proof ceramic blankets under a steel jacket.

“The NTSB is concerned that thermal protection systems designed to simply meet the performance standard in 49 CFR 178.18(a) may not be sufficiently robust to prevent unacceptable performance in accidents involving tank cars transporting flammable liquids,” NTSB said. “The NTSB believes that available thermal protection systems, such as jacketed ceramic blankets that are approved for use on tank cars used to transport liquefied petroleum gas, have the capability to provide protection that significantly exceeds the 49 CFR 179.18(a) performance standard when used on flammable liquids tank cars.”

In addition to new cars, the NTSB wants all existing DOT-111 and CPC-1232 tank cars either off the rails or fully upgraded with thermal protection within five years, despite Canada’s proposed ten-year grace period for new but unjacketed CPC-1232s that the country formally adopted last year as an interim official standard. The NTSB urges U.S. authorities to resist grandfathering the CPC-1232 beyond 2020, and not compromise in the interest of regulatory harmony with Canada.

If industry cannot meet the five-year timeline for full fleet renewal, said the NTSB, trains hauling obsolete DOT-111 and obsolescent CPC-1232 cars could be slow-ordered: “If the DOT finds that tank car shop retrofitting capacity is insufficient to improve the thermal protection and puncture resistance of the existing fleet within an aggressive, phased time schedule, it could consider mandating additional risk mitigation measures on flammable liquids routes, such as significant speed restrictions for each class of track.”

Nominally addressed to the Pipeline and Hazardous Materials Safety Administration (PHMSA), which drafted the Notice of Proposed Rulemaking, the NTSB safety recommendation is aimed squarely at OMB’s last-chance review before the rules are scheduled for final approval in May.

It was President Obama who personally directed PHMSA to refrain from imposing a federal requirement that crude oil be de-gassed at the wellhead and focus instead on tweaking tank car standards. That strategy has failed on both scores. North Dakota declined to require more than minimal “conditioning” of its light crude, and then on March 24, the U.S. Department of Energy reported that no form of untreated crude is safe from exploding in any imaginable tank car, given the intense temperatures generated in a high-energy pileup.

The NTSB’s new safety recommendations are based squarely on “the unacceptable performance of bare steel tank cars” in recent oil train disasters. Four winter derailments of CPC-1232 tank cars carrying a variety of crudes resulted in chain-reaction fireballs minutes and even hours after the derailment event. The bare-metal tank cars were cooked by surrounding “pool fires,” and relief valves were unable to reduce internal pressures sufficiently to prevent the shells from bursting.

“Preliminary investigation results indicate that a total of 28 CPC-1232 compliant tank cars thermally failed in these four accidents,” NTSB said. “One person was injured, and thousands of gallons of crude oil were released, causing significant property damage and environmental pollution. In these four accidents, investigators have found consistent evidence of shell bulging from overpressure, shell material thinning, and tank shell tears in the vapor space of bare steel CPC-1232 tank cars exposed to pool fire conditions. The NTSB concludes that the thermal performance and pressure relief capacity of bare steel tank cars that conform to current federal and industry requirements is insufficient to prevent tank failures from pool fire thermal exposure and the resulting overpressurization.”

The four NTSB recommendations call for sufficient thermal resistance to survive either a 100-minute pool fire or a 30-minute torch fire:

• R-15-14: Require that all new and existing tank cars used to transport all Class 3 flammable liquids be equipped with thermal protection systems that meet or exceed the thermal performance standards outlined in Title 49 Code of Federal Regulations 179.18(a) and are appropriately qualified for the tank car configuration and the commodity transported.

• R-15-15: In conjunction with thermal protection systems called for in safety recommendation R-15-14, require that all new and existing tank cars used to transport all Class 3 flammable liquids be equipped with appropriately sized pressure relief devices that allow the release of pressure under fire conditions to ensure thermal performance that meets or exceeds the requirements of Title 49 Code of Federal Regulations 179.18(a), and that minimizes the likelihood of energetic thermal ruptures.

• R-15-16: Require an aggressive, intermediate progress milestone schedule, such as a 20% yearly completion metric over a five-year implementation period, for the replacement or retrofitting of legacy DOT-111 and CPC-1232 tank cars to appropriate tank car performance standards. This includes equipping these tank cars with jackets, thermal protection, and appropriately sized pressure relief devices.

• R-15-17: Establish a publicly available reporting mechanism that reports at least annually, progress on retrofitting and replacing tank cars subject to thermal protection system performance standards as recommended in safety recommendation R-15-16.

NTSB’s full report can be download by clicking HERE.