Cellular Phones and Other Risks in Classified Areas

United States Department of the Interior

Content:
Kumkum Ray
703-787-1604

Pagemasters:
OMM Web Team

National Safety Alert No. 6
November 5, 2002

Cellular Phones and Other Risks in Classified Areas

This National Safety Alert provides an update to National Safety Alert No. 5, Cell Phone Results in Fire, dated March 6, 2002, which addressed a flash fire on a platform in the Gulf of Mexico OCS. As detailed in National Safety Alert No. 5, a contract panel specialist was working on an open platform master control panel that used supply gas for the instrumentation. The contractor stated he was carrying a cellular phone that was turned on and rang while he was working on the panel. The employee claimed that when he flipped the bottom piece of the cellular phone to answer the call, a flash fire occurred causing second degree burns on his forearms and “sunburn” on his nose and cheeks. At the time National Safety Alert No. 5 was issued, it was believed that the cellular phone may have ignited the flammable gases or vapors in the area of the open platform master control panel when the phone had been flipped open to receive the incoming call.

Both the MMS and the lessee conducted independent investigations of this incident. MMS determined that the platform master control panel was plumbed with poly flow tubing. After the flash fire occurred, the tubing was found to be split. Thus the panel instrument gas leaking from the split tubing provided a source of fuel for the flash fire.

As part of the lessee’s investigation of this fire, they sent the hand held cellular phone involved in the flash fire to an independent third party testing laboratory. At the laboratory, the cellular phone and an identical model phone were tested in an explosive environment under worst case conditions. These tests consisted of placing the phone in a test chamber containing an explosive mixture of oxygen-enriched propane and methane. Inside the test chamber the following phone functions were implemented:

The phone was turned on and off

The phone was open and closed with the power on

Incoming and outgoing calls were made

The two-way paging function was activated

The battery was removed abruptly with the power on

The battery was removed and installed with the power off

Although the cellular phones’ battery provided sufficient energy to ignite the test gases during the testing it did not. As a result, it was the opinion of the independent third party testing laboratory that it is unlikely that the cellular phone would have ignited a flammable mixture of methane or propane under actual field conditions and that the cause of the flash fire was something other than the cell phone.

Based on this information and MMS’s investigation, we were unable to conclusively identify the ignition source of the fire. However, we have not ruled out the possibility that the fire could have been ignited by static electricity, a spark from the metal master control panel door coming into contact with a metal handrail, or a wrench striking metal inside the control panel.

To prevent similar incidents in the future, MMS recommends the following:

Lessees should conduct comprehensive job safety analyses before assigning tasks that require work in classified areas in a hydrocarbon environment.
Class 1, Division 1 locations such as main panel cabinets should be clearly labeled with a warning about the presence of flammable vapors.
Lessees should verify that appropriate material is used for plumbing hydrocarbon media control panels.
Lessees should be aware that cell phones, electronic devices, and electronic instruments may create an ignition source in a classified area. Lessees should train their personnel in the use of these devices in a hydrocarbon environment and issue hot work permits as required for safe operations.
Use of intrinsically safe portable electronic equipment that use low capacitance components, special board layouts, and encapsulation techniques which meet stringent standards (e.g., API RP 14F and 14FZ) for use in hazardous environments should be considered.

For further information, please contact David Nedorostek, (703) 787-1029.

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Last Updated: 02/01/2006, 12:48 PM