Archive for September, 2010
CSB Board Member Mark Griffon Calls on American Society of Mechanical Engineers to Adopt CSB Recommendation Prohibiting Natural Gas Blows at Power Plants
Phoenix, Arizona, September 21, 2010—U.S. Chemical Safety Board (CSB) Member Mark Griffon today called on the American Society of Mechanical Engineers (ASME) to adopt a CSB recommendation calling for natural gas blows to be prohibited during power plant construction.
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The recommendation was one of 18 urgent recommendations issued in June 2010 following a CSB investigation into a powerful natural gas explosion that killed six workers and injured dozens of others at the Kleen Energy plant in Middletown, Connecticut on February 7, 2010, which was under construction. Workers used hundreds of thousands of cubic feet of natural gas to clean debris from gas pipes used to fuel electricity-producing turbines. The gas accumulated in and around the buildings, was ignited by an unknown ignition source, and exploded.
Speaking to a meeting of ASME members in Phoenix who are considering changes to the ASME Code for Pressure Piping Systems, Mr. Griffon said, “The CSB believes that using natural gas or other flammable gases to clean fuel gas piping is inherently unsafe and should be prohibited.” He cited other accidents to show that explosions resulting from flammable gas blows have the potential of causing death, serious injuries, and costly property damage.
Mr. Griffon noted that the practice of using gas blows, or forcing large volumes of flammable gas through piping to clear out debris, was common in construction of electric generating facilities. The CSB investigation of Kleen Energy, resulting in 18 urgent recommendations, states “From a fire and explosion perspective, releasing large volumes of natural gas in the vicinity of workers or ignition sources is inherently unsafe.”
In remarks prepared for the ASME, which is considering the CSB recommendation to prohibit gas blows and use inherently safer methodologies to clean piping, Board Member Griffon said, “It has been argued that the gas blow at Kleen Energy was not conducted properly to ensure the dispersion of the released natural gas and to prevent the gas from encountering ignition sources. This point overlooks the simple fact that cleaning piping with flammable gases presents an inherent explosion hazard. Cleaning piping with flammable gases presents an explosion hazard that cannot be wholly eliminated.”
Even if every effort is made to eliminate ignition sources, such as welding, or electrical equipment not rated for a hazardous environment, he noted, the friction of the gas flowing through the piping can cause an accumulation of static electricity and cause ignition; in addition, sparks from impacts of metal debris striking surfaces when the gas exits the piping can also ignite the gas.
Mr. Griffon noted the CSB investigation found ample alternatives to gas blows which are safer. These methods include blowing air or nitrogen through piping, or by “pigging,” in which a cleaning device is propelled through the pipe using air.
Board Member Griffon noted that that some in industry have already eliminated gas blows. He said that a representative of General Electric, a major gas turbine manufacturer, stated at the CSB public meeting in June that his company greatly discourages gas blows and did not know of any situation where using gas to clean pipes was necessary. The company official said GE wants to “make gas blows something that will not happen again under GE’s watch.” GE also expressly prohibits its own employees from being on site if one of its customers chooses to conduct a blow with natural gas.
Since the public meeting, several other major turbine manufacturers also have reported to the CSB that they already have, or intend to soon develop, guidance that strongly advises their clients away from the practice of natural gas blows.
BP releases investigation report into Deepwater Horizon accident
Sep 09, 2010- BP released their own internal investigation report yesterday into the Deepwater Horizon oil rig explosion, fire, sinking and then massive oil spill caused by the rupturing of the pipeline riser several thousand meters below the ocean surface of the Macondo well. However, there is no one cause that has been listed, but rather several contributing causes have been mentioned. Some of the key noteworthy points in the report are listed below.
Our own comments are highlighted below (in bold italics).
1. Weaknesses in cement design and testing.
2. Failure of the shoe-track barrier in isolating hydrocarbons. The investigation team has reportedly found some clues that identify how the shoetrack cement and the float collar allowed hydrocarbon ingress into the production casing.
3. Acceptance of the negative pressure test before establishing the well integrity-here BP has pointed fingers at the Transocean rig crew as well as at BP’s own rig leadership which “incorrectly” interpreted the test results.
4. Influx was not recognized until the hydrocarbons were in the riser.Apparently almost 40 minutes before the crew started taking action, increase in drill pipe pressure data could be seen-which was not apparently noticed.
5. Wrong actions on diverting the fluids exiting the riser to the Mud-Gas separator, rather than to the overboard diverter line.
6. Once diverted to the Mud-Gas Separator, the fluids got vented onto the rig itself, where it these fluids may have found an ignition source and exploded
7. Failure of the Fire & Gas System to prevent ignition-this point seems a bit debatable, because an F & G system cannot “prevent” a fire from occuring really- all it does it to measure any gas leaks or fires and extinguish them. Apparently the hydrocarbons went into unclassified areas like engine rooms where it could find potential sources of ignition.
Incidentally this is a similar phenomenon that was observed in the infamous Buncefield, UK accident where a large explosion took place.
8. Lastly the Blow Out Preventer (BOP) did not seal the well. The control pods that were supposed to act did not work, a guess is that they got damaged due to the fire and explosion. Consequently a critical solenoid operated valve did not operate. What is more startling and damning however, is that the control pod batteries had inadequate charging, due to which the Solenoid valve did not operate-this is most certainly an oversight by the maintenance personnel who were in charge of the Control & Instrumentation systems on the rig.
Finally the report mentioned that the investigation revealed potential weaknesses in the inspection and maintenance regimes.
Though there will be several more investigation reports from different agencies like the Coast Guard, the US Chemical Safety Board and others, the initial BP investigation does seem to have covered a lot of ground. It raises questions about hazardous area classification, especially on an oil rig where the classification of areas that are classified and “safe” or “non-hazardous” seems a bit arbitrary. If one cannot know which areas of the rig would have the presence of hydrocarbons then there is no point in classifying-one should designate all areas as hazardous, although with different risk profiles such as Zone 1, Zone 2 and so on.
We’re sure this is not the last that would be written on this subject, but it gives a good idea of the importance of two subjects-hazardous area classification and gas monitors
Have a look at the excellent training resources for both of these crucial topics here.
Another Gulf Oil Rig Explosion-Mariner Energy rig accident
Sep 3, 2010 Houma, La — Yet another accident at an Oil Rig in the Gulf of Mexico! An oil rig operated by Mariner Energy Inc in shallow water suffered an explosion. About 13 workers had to jump into the sea, from where they were later rescued. No casualties have been reported. This comes as a bad news to the Oil & Gas industry, which is already battling a mortarium on deepwater drilling in the gulf. Now that this latest accident has taken place in shallow waters raises a lot of question marks over the safety of operations in ALL offshore places, shallow or deep. AS of now no oil spill has been reported, but its too early to say.
Recall that when the first reports of the Deepwater Horizon explosion started coming in the spillage reported was “only a few hundred barrels” and slowly it emerged that hundreds of thousands of barrels may have been spilled. Lets cross our fingers and watch this one.
