Author(s): Fred Durso. Published on November 1, 2011.

The Kleen Energy plant following the explosion.  (Photo: AP/Wide World)

The Making of a Standard
NFPA responded to a deadly power plant explosion in 2010 by creating a new consensus standard in a fraction of the time required to complete a typical document. The result, NFPA 56 (PS), demonstrates the ability of standards development organizations to move quickly to help safeguard lives and property.

NFPA Journal®, November/December 2011 

By Fred Durso, Jr.

Edward Badamo was at home when he heard the distant rumbling sound. It was about 11:15 on a Sunday morning, and at first Badamo, who is chief of the South Fire District in Middletown, Connecticut, and off duty at the time, thought the rumbles were the sounds of his two Rottweiler dogs wrestling. He soon learned otherwise. Badamo’s teenaged son heard the dispatches on his father’s emergency radio and was the first to inform him that the noise was something worse — an explosion had occurred at Kleen Energy, a natural gas-fueled power plant under construction about five miles away.



NFPA senior engineer Denise Beach illustrates several industrial practices covered by NFPA 56.

NFPA Vice President Chris Dubay on the expedited process behind the development of NFPA 56.

Blasts From the Past

Incidents similar to the Kleen Energy explosion underscore dangers of gas blows


February 2010
An explosion occurs at the Kleen Energy power plant in Middletown, Connecticut, during a pipe cleaning procedure using flammable natural gas. Six workers die, and nearly 50 others are injured in the blast

June 2010
The Chemical Safety Board issues its report on the Kleen Energy explosion, which outlines "urgent recommendations" to NFPA and other parties with the intent of regulating the intentional release of natural gas at workplaces

October 2010
NFPA's Standards Council establishes a new NFPA technical committee to develop a standard on gas process safety

November 2010
NFPA's Board of Directors authorizes the Standards Council to implement the development of the new standard using expedited procedures set forth by the American National Standards Institute

March 2011
NFPA's Standards Council approves the committee scope and roster for the gas process safety standard

April-July 2011
The Technical Committee on Gas Process Safety convenes once a month for four months and develops NFPA 56 (PS), Fire and Explosion Prevention During Cleaning and Purging of Flammable Gas Piping Systems

August 2011
The Standards Council issues NFPA 56 (PS)

Badamo arrived at Kleen Energy minutes later and witnessed a horrific scene: large plumes of smoke and fire erupting from the rear of the building, bloodied workers carrying their injured colleagues to safety as other workers frantically searched for survivors, ignoring the smoke and flames and live electrical hazards. The damage was so catastrophic that it took Badamo, who was the incident commander, and the other first responders nearly two days to account for all of the plant’s employees, both alive and deceased. Six workers died and nearly 50 others were injured.

"It was a very complex scene that required a large number of resources from various agencies to mitigate hazards, rescue victims, and provide support for emergency management," Badamo says. "I’d been on site prior to this accident. To see it completely destroyed, it took a few days for that to sink in."

The explosion, which occurred on February 7, 2010, was caused by a "gas blow," according to an investigation by the U.S. Chemical Safety Board (CSB). Gas blows are a commonly used cleaning procedure in natural gas-fueled power plants, where flammable gas is blown through piping at high pressure to remove debris such as welding slag or other foreign materials. Ten minutes before the Kleen Energy explosion, for example, approximately 480,000 standard cubic feet (13,592 cubic meters) of natural gas was released, according to the investigation. The gas was being vented from an open-ended pipe into an area where dissipation was impeded by other equipment at the level of discharge before it found an ignition source. Construction of the plant, which was close to completion when the explosion occurred, was heavily regulated, but there was no standard guiding the gas-blowing procedure.

NFPA acted swiftly to address this concern through the development of its first provisional standard, NFPA 56 (PS), Fire and Explosion Prevention During Cleaning and Purging of Flammable Gas Piping Systems ( The new provisions now prohibit the use of flammable gas during cleaning procedures while safeguarding a range of activities related to cleaning and repairing piping systems.

The introduction of a fast-track provisional standard also represents an important step in NFPA’s evolution as a standards development organization. Using a framework for expedited standards created by the American National Standards Institute (ANSI), NFPA developed its own procedures to govern the use of a provisional standard process, one that complies with, and exceeds, the minimums set by the ANSI requirements.

The provisional standard process means that safety issues can be addressed — in the form of a consensus standard — much faster than they could before. NFPA’s code development process, for example, typically lasts 104 weeks, and if contested through certified amending motions, the process can take as long as 141 weeks. NFPA 56 (PS) was developed in less than 24 weeks, from the first technical committee meeting to issuance by the Standards Council. Fewer than 76 weeks elapsed from the Kleen Energy explosion to the issuance of a consensus standard addressing the procedures that led to the disaster.

"This is an example of the critical role NFPA plays in providing codes and standards for use by government and other entities throughout the world," says NFPA President James Shannon. "Our ability to bring together the right people at the right time and to facilitate a consensus process in very short order resulted in a standard that will save lives and prevent a tragedy like the one in Connecticut from happening in the future."

Sense of urgency   
Despite the Kleen Energy tragedy and a handful of other gas-blow procedures that have gone awry, flammable gas is still commonly used during certain pipe cleaning procedures. Two months after the Kleen Energy explosion, the CSB, a federal agency that investigates industrial accidents, initiated an industry survey that identified natural gas blows as a principal procedure for cleaning newly installed fuel gas piping. About half of the respondents who used the procedure indicated they did not follow a technical evaluation for determining how much gas is actually needed to effectively clean pipes. Underscoring these findings is that nearly 4,250 natural gas-fired power plants currently operate in the U.S, and that 145 additional plants are expected to be operational nationwide by 2016, according to the electric power plants database developed by Platts, a global provider of energy information.

Following its Kleen Energy investigation, the CSB announced urgent recommendations on gas procedures to NFPA and other standards-development organizations. NFPA’s Board of Directors responded by authorizing NFPA’s Standards Council to evaluate and, if warranted, execute the development of a gas process safety standard using an expedited process approved by ANSI. Developed in 2003 and referenced in an annex of the ANSI Essential Requirements, the process outlines circumstances when a provisional standard is applicable. The Standards Council determined that NFPA’s proposed standard met ANSI’s criteria, since it would "result in an improvement to the safeguarding of life, and there’s a well-established need for the prompt dissemination of information that addresses an emergency situation," as stated in the ANSI procedures.

NFPA is only the second organization to use the provisional standard process. Following incidents of children being strangled by window blind cords, the Window Covering Manufacturers Association used ANSI’s procedures to develop a provisional standard last year aimed at improving the safety of corded products. "The provisional standard option provides a readily available process when there is an urgent need for an interim document that addresses life safety, an emergency situation, or other special circumstance," says ANSI President and CEO S. Joe Bhatia. "NFPA’s decision to rely upon the provisional standard process will help deliver new safety criteria for the commissioning and maintenance of fuel gas piping systems."

At its October meeting last year, NFPA’s Standards Council voted to establish the NFPA 56 Gas Process Safety Technical Committee. Five months later, the Council approved the committee scope and roster while urging the committee to proceed expeditiously in the standard’s development. Industries sitting on the committee include the American Gas Association, insurance agencies, consulting firms, and energy companies. The committee held its first meeting in April.

One of the committee’s first actions was to expand the document’s scope to include new and existing flammable gas piping systems — not just fuel gas — for electric-generating plants and industrial, commercial, and institutional applications. Piping systems covered in other NFPA documents—including NFPA 2, Hydrogen Technologies CodeNFPA 54, National Fuel Gas CodeNFPA 58, Liquefied Petroleum Gas Code; and NFPA 59A, Production, Storage, and Handling of Liquefied Natural Gas — are not applicable, since these codes have specific piping requirements.

The Standards Council officially approved NFPA 56 (PS) in August. "The committee demonstrated incredible dedication to the effort by showing up every four weeks on very short notice," says Denise Beach, staff liaison for NFPA 56 (PS) and an NFPA senior engineer. "This standard represents a commitment not just on the part of NFPA, but more importantly on the part of our volunteers as well."

ANSI regulations require a provisional standard to enter into a full revision process of its respective standards development organization within 45 days of issuance. In the case of NFPA 56 (PS), the standard has entered NFPA’s annual 2013 revision cycle, and public proposals on the new edition — which would drop the provisional, or PS, stipulation — are now being accepted. The deadline for submitting proposals for the Annual 2013 revision cycle is November 25. NFPA will consider developing other provisional standards if other emergencies require immediate action from the codes and standards community.

"The provisional standard process is a method to address urgent safety concerns while maintaining the integrity of NFPA’s open consensus process," says Christian Dubay, NFPA’s vice president of Codes and Standards and chief engineer. "This gives us a unique tool to address the most pressing needs, should others arise."

Standard procedures      
Cleaning new piping is a necessary step for natural gas power plants with combustion turbines using natural gas as a fuel source. The piping extends from a gas supply line to the turbine and must be cleaned to remove any debris that might damage the turbine.

Gas blows, or the cleaning process that forces highly pressurized gas through pipes to remove debris, led to the release of more than 2 million standard cubic feet (56,634 cubic meters) of natural gas at the Kleen Energy plant the day of the accident. Though vented outdoors, the gas accumulated in an area congested with large structures and power generation equipment. The ignition source was not determined, but there were many probable causes, including welders at work or a spark created from debris being expelled at high speed from the pipes. Furthermore, the CSB investigation report states that workers didn’t conduct a safety meeting or review the gas-blow procedures on the day of the incident.

Addressing these concerns, NFPA 56 (PS) requires an extensive written procedure for pipe cleaning and purging, taking into account the control of ignition sources, site-specific processes, and environmental conditions. "The document includes an extensive list of items and conditions that need to be addressed in the written procedure," Beach says. "The standard recognizes that each installation and related procedure will be unique. The standard doesn’t tell you specifically how to address them, but it provides a template for procedures to be developed using good engineering practice."

The standard also prohibits any type of flammable gas for internal pipe cleaning. Approved alternatives include compressed air, inert (and therefore nonflammable) gases like nitrogen or helium, as well as steam and water. Also permitted under certain circumstances are internal cleaners known as "pigs," formfitting devices that can include scrub brushes; once the pipe is pressurized by gas, the pig is launched from one end of the pipe to the other, picking up debris as it goes.

NFPA 56 (PS) also accounts for "purging systems into service," a process that replaces air or inert gas in a closed system with a flammable gas, and "purging systems out of service" by removing flammable gas. The standard calls for specific procedures to accompany these steps, including the selection of a safe, outdoor purging location and appropriate gas detection equipment.

"Purging is a more routine procedure since it happens more frequently than pipe cleaning," says Beach. "Whenever you need to take a system out of service for repair, you need to purge it out of service. Then you have to purge it back into service. If someone is currently purging in accordance with another NFPA standard, such as NFPA 54, they will still purge in accordance with that standard."

Put into practice 
NFPA’s first provisional standard was celebrated by Connecticut’s elected officials, who announced at a September news conference in Middletown that the state had passed legislation to prohibit all gas blows in accordance with NFPA 56 (PS). Connecticut is currently the only state to ban the procedure.

"The investigation into what happened [at Kleen Energy] resulted in this new worker protection standard — the first of its kind to address this dangerous practice," says Connecticut Congresswoman Rosa L. DeLauro, who championed the legislation. "We can say that the six men who died that day didn’t die in vain, and that this tragedy in Middletown will be the last of its kind."

Following Connecticut’s actions, the CSB is urging federal regulators to institute a nationwide ban on using flammable gases during pipe cleaning. "NFPA’s actions send a clear message to industries that gas blows are inherently unsafe," says CSB chair Rafael Moure-Eraso. "What would really establish this on a permanent basis is if there could be federal regulation under OSHA [the Occupational Safety and Health Administration] to specifically adopt NFPA 56 (PS) or address gas blowing by forbidding the act."

OSHA’s Process Safety Management Standard handles the prevention of catastrophic release of flammable substances. The provisions, however, don’t apply to the type of gas-blow procedure that led to the explosion at Kleen Energy or flammable gases used solely for workplace fuel consumption at this and other power plants, according to the CSB investigation report. A standard specific to these procedures is "under consideration," says Robert Kowalski, area director for OSHA’s office in Bridgeport, Connecticut. "Now that NFPA 56 (PS) has been created, if we find a company not complying with the standard, we can use that as a support for a general duty clause, which requires an employer to maintain a safe and healthy place for employees," Kowalski says. "That’s the importance of this standard."

OSHA has cited three construction companies and 14 site contractors assigned to the Kleen Energy site with 370 alleged workplace safety violations and $16.6 million in penalties in connection with the 2010 explosion. The three construction companies are contesting the citations, and the cases are in litigation. O&G Industries, Inc., the project’s general contractor, did not respond to interview requests by NFPA Journal. Kleen Energy Systems LLC declined comment.

NFPA’s Dubay hopes other states will look to Connecticut’s experience as an example for achieving national change. "While Connecticut experienced this tragedy and has reacted to it by taking a leadership position, they’re also helping to set the bar in other states and jurisdictions," he says. 

Fred Durso, Jr. is staff writer for NFPA Journal.

Blasts From the Past
Incidents similar to the Kleen Energy explosion underscore dangers of gas blows

A gas-blow explosion occurred in 2003 at Calpine’s Wolfskill Energy Center in Fairfield, California.
The Kleen Energy incident wasn't the first time gas blows-the process of using flammable gas to clean new piping at power plants and other settings-resulted in an explosion, according to the Chemical Safety Board's Kleen Energy investigation report.
  • Pressurized natural gas was used during a pipe cleaning procedure in a highly congested area at Calpine's Wolfskill Energy Center in Fairfield, California, in 2003. Gas accumulated in an area containing between 2,000 and 9,000 cubic feet (between 57 and 255 cubic meters) of confined space and ignited, most likely from static electricity generated from the gas flowing at a high velocity through underground piping. The report states that the explosion was powerful enough to shatter windows a quarter mile away and was heard up to 10 miles (16 kilometers) from the site. Though seven people were present during the gas blow, nobody was injured.
  • A similar incident occurred in 2001 at the FirstEnergy power generation station in Lorain, Ohio. Workers used an air blow, pigging, and natural gas blow, respectively, to clean fuel gas piping leading to the turbine. A three-foot stack served as the fuel gas outlet during the blow. The gas ignited, creating a 30- to 40-foot (9- to 12-meter) flame shooting from the stack. The likely cause was a spark from a metal particle hitting a nearby metal surface. There were no injuries, but damage occurred to nearby electrical cables.

- Fred Durso, Jr.