Accident: Kleen Energy Natural Gas Explosion
Location: Location: Middletown, CT
Accident Occurred On: 02/07/2010 | Final Report Released On: 06/28/2010
Accident Type: Flammable Vapor
Investigation Status: The CSB's final report was approved at a public meeting in Portland, CT, on June 28, 2010.
Six workers were fatally injured during a planned work activity to clean debris from natural gas pipes at Kleen Energy in Middletown, CT. To remove the debris, workers used natural gas at a high pressure of approximately 650 pounds per square inch. The high velocity of the natural gas flow was intended to remove any debris in the new piping. During this process, the natural gas found an ignition source and exploded.
Make appropriate changes to the 2012 version of Power Piping, ASME B31.1, to require the use of inherently safer fuel gas piping cleaning methodologies rather than natural gas blows. At a minimum, for the cleaning or flushing methods discussed in B31.1 paragraph 122.10, require the use of inherently safer alternatives such as air blows and pigging with air as the motive force in lieu of flammable gas.
Work with the six turbine manufacturers identified in this document – General Electric, Siemens, Solar, Mitsubishi Power Systems, Pratt & Whitney, and Rolls-Royce – to publish technical guidance addressing the safe cleaning of fuel gas piping supplying gas turbines. At minimum: a. For cleaning methodology, require the use of inherently safer alternatives such as air blows and pigging with air in lieu of flammable gas. b. Provide comprehensive technical guidance on inherently safer methods for cleaning fuel gas piping, such as the use of air or pigging with air.
Provide to your customers: a. Comprehensive technical guidance on inherently safer methods for cleaning fuel gas piping, such as the use of air or pigging with air. b. Comprehensive Cleaning Force Ratio (CFR) guidelines, specifying both the upper and lower limits required to obtain satisfactory cleaning for the fuel gas piping for purposes of the warranties of the turbines. c. Warnings against the use of fuel gas to clean pipes.
Work with the Electric Power Research Institute to publish technical guidance addressing the safe cleaning of fuel gas piping supplying gas turbines. At minimum: a. For cleaning methodology, require the use of inherently safer alternatives such as air blows and pigging with air in lieu of flammable gas. b. Provide technical guidance for the safe and effective use of alternative methods for cleaning such as air and pigging with air.
Enact legislation applicable to power plants in the state that prohibits the use of flammable gas that is released to the atmosphere to clean fuel gas piping.
Adopt the current version of NFPA 54 as amended pursuant to 2010-01-I-CT-R2.
Enact a Tentative Interim Amendment and permanent changes to the National Fuel Gas Code (NFPA 54/ANSI Z223.1) that address the safe conduct of fuel gas piping cleaning operations. At a minimum: a. Remove the existing NFPA 54 fuel gas piping exemptions for power plants and systems with an operating pressure of 125 pounds per square inch gauge (psig) or more. b. For cleaning methodology, require the use of inherently safer alternatives such as air blows or pigging with air in lieu of flammable gas.
Promulgate regulations that address fuel gas safety for both construction and general industry. At a minimum: a. Prohibit the release of flammable gas to the atmosphere for the purpose of cleaning fuel gas piping. b. Prohibit flammable gas venting or purging indoors. Prohibit venting or purging outdoors where fuel gas may form a flammable atmosphere in the vicinity of workers and/or ignition sources. c. Prohibit any work activity in areas where the concentration of flammable gas exceeds a fixed low percentage of the lower explosive limit (LEL) determined by appropriate combustible gas monitoring. d. Require that companies develop flammable gas safety procedures and training that involves contractors, workers, and their representatives in decision-making.