Corrosion of Fire Protection System Lines at the Nevada Test Site's Device Assembly Facility

The Device Assembly Facility fire suppression system consists of a mortar-lined, ductile iron header loop line plus smaller-diameter, coal tar enamel-lined, carbon steel “lead-in” lines that run underground from the header loop line to a variety of risers inside the facility.  Particles and flakes of the coal tar enamel lining have been appearing in water used to flush the fire suppression piping since the installation of the system.  An assessment of the system to determine why the lining continues to delaminate from the inside of the lead-in lines was recently performed.  In general, the assessment showed that the lead-in lines appear to have been improperly prepared for the application of the lining.  Additionally, welding activity on the pipes during construction damaged the lining at the joints providing initiation points for lining delamination.  Water testing confirmed that MIC-inducing bacteria are present in all the lead-in lines.  MIC activity, tubercles and pitting were observed in most lines at points of lining failure.  Details of the examination and inspection results are presented herein.