Follow us on Twitter Follow us on LinkedIn Like us on Facebook Follow us on Instagram Visit the TPC Store
Search the site




Coatings Industry News

Main News Page

Pipe Corrosion Blamed in UT Blast

Friday, April 18, 2014

More items for Health & Safety

Comment | More

Pipeline walls thinned by corrosion and uninspected for over 20 years caused a major explosion at a Utah refinery—a scenario that has become “all too familiar,” federal officials announced.

When a 10-inch pipe failed in November 2009 at the Silver Eagle Refinery in Woods Cross, UT, it caused a powerful blast that damaged 100 nearby homes and knocked four workers to the ground.

The workers were not seriously injured, but two homes were severely damaged, including one that was knocked off its foundation.

Silver Eagle Refinery
Security video footage obtained by the CSB

It took less than a second for the pipe the fail and the explosion to occur, releasing hydrogen and other gases and damaging 100 nearby homes. The circle indicates the area of the pipe rupture.

In a metallurgical report released April 10, the U.S. Chemical Safety Board determined that the pipe had become "dangerously thin" from corrosion, leading to a massive release of hydrogen, which caught fire immediately and exploded. The pipe was located at the bottom of a reactor in the mobile distillate dewaxing unit.

According to the report, the pipe segment that failed had no record of ever being inspected for corrosion in the 21 years since it had been installed.

It was the second incident at the plant that year. On Jan. 12, 2009, four people were injured in a flash fire after a large flammable vapor cloud was released from an atmospheric storage tank.

The failure study and analysis was performed by Exponent Failure Analysis Associates, a Texas-based engineering and scientific consulting company.

'Same Syndrome'

"The findings in the Exponent report are all too familiar," said CSB Chairman Rafael Moure-Eraso.

"This is the same syndrome we found in the Bay Area Chevron refinery fire of 2012 and the Tesoro refinery explosion and fire that killed seven in Anacortes, Washington, in 2010," Moure-Eraso said.

Examination of the ruptured Utah pipe segment and adjacent piping "clearly indicates" wall thinning, the investigation team said.

The failed segment had a wall thickness of 0.039 inch.

"Mechanical integrity programs at refineries repeatedly primarily emphasize inspection strategies, rather than the use of inherently safer design, to control the damage mechanisms that ultimately cause major process safety incidents," Moure-Eraso said.

Delayed Investigation

A rash of such incidents in recent years, in fact, slowed the Utah investigation, Moure-Eraso said.

"This is an investigation where we have had to delay its completion due to, ironically, a pressing series of accidents in the oil production and refining sector," he said.

Although the completed report was released April 10, it was submitted to the CSB in June 2013.

"However, I want people to know that work has been continuing as this report shows, and that the CSB is working hard to assure refineries and indeed all chemical operations are operated more safely," Moure-Eraso said.

pipe corrosion
Exponent Failure Analysis Associates via CSB

Investigators discovered one end of the ruptured pipe wrapped around a reactor support beam.

Silver Eagle Refinery's website says the company is committed to safety and has "embarked" since the accident "on a bolt-by-bolt, pipe-by-pipe, thought-by-thought, action-by-action reevaluation of all its operations."

"Silver Eagle is now working constantly and effectively with a total commitment to safe thinking, safe actions, safe practices and safe processes. We understand that nothing is more important than the safety and wellbeing of our employees, our neighbors, our communities and our environment."

Multiple Gases Released

The elbow adjacent to the failed pipe had an original thickness of 0.719-inch. A 2007 measurement found a wall thickness of 0.483 inch, "indicating years of thinning had taken place," the report said.

After the rupture, high-pressure gas escaped from both ends of the failed pipe segment. One end ended up wrapped around a reactor support beam; the other was attached to the bottom of the reactor.

Only 0.66 seconds elapsed between the rupture and the explosion, according to the report, citing a security video. This time was used to calculate the amount of each type of gas released at the time of the explosion, which primarily included hydrogen, followed by nitrogen, methane, and hydrocarbons.

1966 Structure

The piping was installed and put into service in 1993, and the reactor pressure vessel was originally constructed in 1966.

Silver Eagle Refinery

Parts of the system were installed in 1993, but "no documentation has been produced indicating that the wall thickness of the straight segment was ever measured from build date to the time of the incident," the report said.

However, the report says it could not be determined if the elbow and straight segments were new when they were installed in 1993, or if they had been used with the reactor pressure vessel when it previously functioned as a lube stock hydrotreater.

"Regardless, to date no documentation has been produced indicating that the wall thickness of the straight segment was ever measured from build date to the time of the incident," the report noted.

Years of Thinning

Ultrasonic testing readings from 1993 on the elbow found thicknesses ranging from 0.671 to 0.805 inches. An October 2007 inspection sheet noted that the section had an "original thickness" of 0.791 inch.

It is unknown how the inspector determined the original thickness, since no documents or design drawings were ever produced, the report said.

By the time of the October 2007 inspection, the elbow was showing wall thinning from its 14 years in service, measuring 0.483 inch in some locations.

According to the report, the primary cause of the thinning was sulfidation corrosion; turbulent flow at the elbow likely caused the most significant thinning at the rupture location just downstream of the elbow, it said.


Tagged categories: Chemical attack; Corrosion; Explosions; Inspection; Oil and Gas; Pipeline; U.S. Chemical Safety Board

Comment Join the Conversation:

Sign in to our community to add your comments.

Clemco Industries Corp.
Maximum Dust Suppression Systems Start at $14,950
The system comprises proven technology and equipment with user-friendly flexibility in mind. See it in action.

SABRE Autonomous Solutions
Removing blasting operators from harmful environments is our key objective.

Detail Masters
Overspray Removal
We offer professional, turnkey service and unparalleled quality!
Our process can save hundreds— even thousands of dollars. It's fast, environmentally safe and 100% guaranteed.

SAFE Systems, Inc.
SAFE Systems'
Blast Lights &
Deadman Switches
Halogen or LED blast lights available with our NEW urethane bumper. Switches available in many colors for color coding your hoses.

Upgrade with the Bullard GenVX
Click here to learn how you can get a GenVX Helmet and Win.

Fischer Technology Inc.
DUALSCOPE®FMP100 with DataCenter IP
Transfer customized inspection plans from PC to FMP100 using step-by-step guidance with prompts and pictures throughout the measurement procedure

Tnemec Company, Inc.
Online Coating Courses from Tnemec
For decades, Tnemec has offered its expertise to clients presenting face-to-face coatings courses. Now, these presentations are available to anyone for CEUs at Tnemec University.

Waterjet Technology Association (WJTA)
Click to register today!
See the latest automated and handheld UHP waterblasting tools/systems/products. Exhibits, live demos, educational sessions, waterjet short course, networking.

KTA-Tator, Inc. - Corporate Office
New KTA Pipeline Inspection Kit
• Defelsko standard memory body
• Positector FTS 0-250 mils, cabled dry film thickness probe
• NEW Positector Shore D hardness probe
• All essential inspection equipment!

Jotun Paints Inc.
Jotachar JF750 - The Time Saving Solution
The only mesh free solution for jet fire scenarios. Jotachar saves installation time and material costs - the next generation of epoxy passive fire protection.


Technology Publishing Co., 1501 Reedsdale Street, Suite 2008, Pittsburgh, PA 15233

TEL 1-412-431-8300  • FAX  1-412-431-5428  •  EMAIL

The Technology Publishing Network

Durability + Design PaintSquare the Journal of Protective Coatings & Linings Paint BidTracker

EXPLORE:      JPCL   |   PaintSquare News   |   Interact   |   Buying Guides   |   Webinars   |   Resources   |   Classifieds
REGISTER AND SUBSCRIBE:      Free PaintSquare Registration   |   Subscribe to JPCL   |   Subscribe to PaintSquare News
MORE:      About   |   Privacy policy   |   Terms & conditions   |   Site Map   |   Search   |   Contact Us