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DOE/EH-0272 --- Issue No. 92-02 --- 09/92
Failure of Thermo-Lag Fire Barrier System
PRODUCT
Thermo-Lag 330 is manufactured and distributed by Thermal Science, Inc.
(TSI) of St. Louis, Missouri. TSI has represented the product as being
capable of achieving 1- and 3-hour fire resistance ratings. Since the
early 1980s, it has been routinely installed in commercial nuclear
facilities to protect safety-related cables in conduits and cable trays.
Additional applications include the construction of fire walls,
partitions, vaults, and the protection of structural steel. TSI product
literature indicates that Thermo-Lag 330 materials have also been used in
various applications at non-nuclear industrial facilities.
PROBLEM
Recent fire test results have revealed that this product may not provide
the represented level of fire protection. Its application may result in
the degradation of electrical cable insulation. The resulting excessive
temperatures could reduce the normal life expectancy of the cables and
compromise the safety-related systems associated with those cables.
The Nuclear Regulatory Commission (NRC) issued Bulletin 92-01 on June 24,
1992, which addressed concerns resulting from tests conducted by Texas
Utilities (TU) Electric on Thermo-Lag 330. TU Electric performed a
variety of 1-hour fire endurance tests on Thermo-Lag 330 representing
cable tray and conduit mockups typical of existing plant configurations.
Stock material was used to build the mockups. Installation was done in
accordance with TSI procedures. In one test, joint separation was
observed approximately 18 minutes into the test. The internal
temperatures within the protected envelope exceeded 325 degrees Fahrenheit
approximately 28 minutes into the test. The joint separated after 41
minutes, resulting in a break of circuit integrity and fire damage to the
cables.
The NRC considered the failures of the recent Thermo-Lag fire barrier
endurance testing and determined that the 1-hour and 3-hour preformed
Thermo-Lag 330 assemblies installed on small conduits and wide cable trays
(wider than 14 inches) do not provide the level of safety required by NRC
fire protection criteria.
On the basis of these circumstances, DOE has concluded that the Thermo-Lag
330 fire barrier system on small conduits and wide cable trays does not
provide mandated levels of safety as required by
DOE Order 5480.7, "Fire
Protection."
RECOMMENDATIONS
The following actions are recommended for all DOE facilities:
- Identify all areas using either 1- or 3-hour preformed Thermo-Lag 330 panels and conduit
shapes.
- Implement appropriate compensatory measures, such as fire watches, pending long-term
mitigation.
- Implement a plan to replace the product with an approved fire-rated barrier system.
TECHNICAL CONTACTS
Dennis Kubicki, EH-31.3 301-903-4794
Chuck Ramsey, NS-10 301-903-5999
This Safety Note is one in a series of publications issued by EH to share
occupational safety information throughout the DOE complex. To be added
to the Distribution List or to obtain copies of the publication, call
(615)576-3482. For additional information regarding the publications,
call Barbara Bowers, Safety Performance Indicator Division, Office of
Environment, Safety and Health, U.S. Department of Energy, Washington, DC
20585, (301)903-3016.
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