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: NIST creates polycyclic aromatic hydrocarbon structure index

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

Desktop device to make key gun part goes on sale in US

10 hours ago

The creator of the world's first 3D plastic handgun unveiled Wednesday his latest invention: a pre-programmed milling machine that enables anyone to easily make the core component of a semi-automatic rifle.

Minimally invasive surgery with hydraulic assistance

16 hours ago

Endoscopic surgery requires great manual dexterity on the part of the operating surgeon. Future endoscopic instruments equipped with a hydraulic control system will provide added support during minimally ...

Analyzing gold and steel – rapidly and precisely

18 hours ago

Optical emission spectrometers are widely used in the steel industry but the instruments currently employed are relatively large and bulky. A novel sensor makes it possible to significantly reduce their size ...

More efficient transformer materials

18 hours ago

Almost every electronic device contains a transformer. An important material used in their construction is electrical steel. Researchers have found a way to improve the performance of electrical steel and ...

Sensor network tracks down illegal bomb-making

19 hours ago

Terrorists can manufacture bombs with relative ease, few aids and easily accessible materials such as synthetic fertilizer. Not always do security forces succeed in preventing the attacks and tracking down ...

Miniature camera may reduce accidents

19 hours ago

Measuring only a few cubic millimeters, a new type of camera module might soon be integrated into future driver assistance systems to help car drivers facing critical situations. The little gadget can be ...

User comments : 0