Summary of urgent recommendations approved by CSB regarding gas cleaning and purging practices.

Pursuant to its authority under 42 U.S.C. § 7412(r)(6)(C)(i) and (ii), and in the interest of preventing the serious harm that could result if the hazards underlying the explosions at Kleen Energy, ConAgra and other related incidents are not promptly rectified, the U.S. Chemical Safety Board (CSB) makes the following urgent safety recommendations:

Occupational Safety and Health Administration (OSHA)
Promulgate regulations that address fuel gas safety for both construction and general industry. At a minimum:
  1. Prohibit the release of flammable gas to the atmosphere for the purpose of cleaning fuel gas piping.
  2. 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.
  3. 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.
  4. Require that companies develop flammable gas safety procedures and training that involves contractors, workers, and their representatives in decision-making.
National Fire Protection Association (NFPA)
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:
  1. 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.
  2. For cleaning methodology, require the use of inherently safer alternatives such as air blows or pigging with air in lieu of flammable gas.
American Society of Mechanical Engineers (ASME)
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.

Major Gas Turbine Manufacturers
  • General Electric
  • Siemens
  • Solar
  • Mitsubishi Power Systems
  • Pratt & Whitney
  • Rolls-Royce
Provide to your customers:
  1. Comprehensive technical guidance on inherently safer methods for cleaning fuel gas piping, such as the use of air or pigging with air.
  2. 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.
  3. Warnings against the use of fuel gas to clean pipes.
Major Gas Turbine Manufacturers
  • General Electric
  • Siemens
  • Solar
  • Mitsubishi Power Systems
  • Pratt & Whitney
  • Rolls-Royce
Work with the Electric Power Research Institute to publish technical guidance addressing the safe cleaning of fuel gas piping supplying gas turbines. At minimum:
  1. For cleaning methodology, require the use of inherently safer alternatives such as air blows and pigging with air in lieu of flammable gas.
  2. Provide technical guidance for the safe and effective use of alternative methods for cleaning such as air and pigging with air.
The Governor and Legislature of the State of Connecticut
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 the recommendation to the NFPA.

The Board further authorizes and directs the chairperson to send correspondence to the governors of the other 49 states urging them to review the CSB's findings concerning the explosion at Kleen Energy, the CSB's recommendations to Connecticut, existing state regulations concerning natural gas safety, and to enact any necessary changes to state regulations and codes to prohibit the release of natural gas to the atmosphere during pipe cleaning operations at power plants and other similar facilities.

Electric Power Research Institute (EPRI)
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:
  1. For cleaning methodology, require the use of inherently safer alternatives such as air blows and pigging with air in lieu of flammable gas.
  2. Provide comprehensive technical guidance on inherently safer methods for cleaning fuel gas piping, such as the use of air or pigging with air.


Complete text and supporting documentation are available at www.csb.gov.

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