In response to a February blast that killed six workers at a Connecticut powerplant under construction, the U.S. Chemical Safety Board voted late last month to recommend a ban on use of natural gas to clean pipes. It also called for an end to venting or purging gas indoors, which triggered a fatal factory explosion in 2009 in North Carolina. Board experts probed both accidents on-site. The board also urged the U.S. Occupational Safety and Health Administration to develop rules to ban both practices and for the National Fire Protection Association to take similar action through code revisions. The recommendations were among 18 approved by the board following an investigation that found 2 million standard cu ft of natural gas was released into the atmosphere before the blast at the plant, owned by Kleen Energy. The board also seeks related safety improvements from state governments, gas turbine manufacturers, the American Society of Mechanical Engineers and the Electric Power Research Institute. A spokesman for O&G Industries, the project’s Torrington, Conn.-based contractor, says it supports the gas- cleaning ban and will forego the practice as the plant is rebuilt, even if regulators do not adopt board proposals.