NIST analysis helps the US Chemical Safety Board pinpoint root cause of pressure vessel failure

Jan 08, 2014 by Jim Fekete
NDK Crystal damage after the incident. The  force of the explosion blew out most of the wall  panels. Credit: CSB

In 2009, a violent rupture of a 50-foot pressure vessel used to produce synthetic crystals at the NDK Crystal facility in Belvidere, Illinois fatally injured a member of the public and caused significant property damage to the plant itself and the surrounding area. In response to the accident, scientists from NIST's Material Measurement Laboratory were approached by the U. S. Chemical and Hazardous Material Safety Board (CSB) to review data and assist in identifying the failure mechanism. The review found strong evidence of stress corrosion cracking (SCC) on and near the inner diameter of the vessel fragment, and a reduction in material toughness during service. This combination likely resulted in a flaw reaching critical size, causing the catastrophic failure. The results were included in CSB's recently published final report on the incident investigation.

In order to reach its conclusions, NIST scientists reviewed over 1000 pages of documents, including chemical and mechanical property data, micrographs, material standards, code documents and results from ultrasonic examinations. The NIST review identified stress corrosion cracking as the most likely cause of the extensive cracking found in the . The review also revealed possible reduction in caused by temper embrittlement in the failed vessel, based on comparisons of Charpy impact test data after fabrication and after failure. In addition, NIST provided a fracture mechanics analysis which concluded that though the vessel entered service in a safe condition, the SCC-caused cracking, along with the reduction in fracture toughness of the steel, resulted in the vessel reaching a critical stress intensity, and subsequent catastrophic failure.

CSB's mission is the investigation of industrial accidents and determination of their root cause, in order to recommend changes to safety procedures, codes and standards, resulting in safer plants, workers and communities. As part of CSB's network of experts, NIST provides expert, independent technical analysis based on its many years of research in structural reliability. CSB expects to continue engaging NIST in investigations where material failure is suspected of playing a role.

Explore further: American Chemical Society issues guidelines for safer research laboratories

add to favorites email to friend print save as pdf

Related Stories

NIST tornado reports urge new safety standards

Dec 05, 2013

Nationally accepted standards for building design and construction, public shelters and emergency communications can significantly reduce deaths and the steep economic costs of property damage caused by tornadoes. ...

Recommended for you

A smart prosthetic knee with in-vivo diagnoses

Apr 22, 2014

The task was to develop intelligent prosthetic joints that, via sensors, are capable of detecting early failure long before a patient suffers. EPFL researchers have taken up the challenge.

Old tires become material for new and improved roads

Apr 22, 2014

(Phys.org) —Americans generate nearly 300 million scrap tires every year, according to the Environmental Protection Agency (EPA). Historically, these worn tires often end up in landfills or, when illegally ...

Students take clot-buster for a spin

Apr 21, 2014

(Phys.org) —In the hands of some Rice University senior engineering students, a fishing rod is more than what it seems. For them, it's a way to help destroy blood clots that threaten lives.

User comments : 0

More news stories

Amazon Prime wins streaming deal with HBO

Amazon scored a deal Wednesday to distribute old shows from premium cable TV channel HBO to its monthly Prime subscribers, landing a blow on rival Netflix in the streaming video battle.

Is nuclear power the only way to avoid geoengineering?

"I think one can argue that if we were to follow a strong nuclear energy pathway—as well as doing everything else that we can—then we can solve the climate problem without doing geoengineering." So says Tom Wigley, one ...

Robot scouts rooms people can't enter

(Phys.org) —Firefighters, police officers and military personnel are often required to enter rooms with little information about what dangers might lie behind the door. A group of engineering students at ...

Cyber buddy is better than 'no buddy'

A Michigan State University researcher is looking to give exercise enthusiasts the extra nudge they need during a workout, and her latest research shows that a cyber buddy can help.