International Airport System Cleaned to Correct for Microbiologically
Myron Shenkiryk, h.e.r.c. Products
effects of corrosion, especially Microbiologically Influenced Corrosion
(MIC), in fire protection systems are costly and potentially disastrous.
Pinhole leaks are one obvious indication that MIC is present. The cost
of lost time and damage to products and equipment from the leaks is
often many times that of the necessary repairs. Another MIC problem
is the buildup, or "tuberculation," inside the piping impacts the hydraulic
characteristics of the pipe and can break off into pieces that could
plug a sprinkler. In recent years the industry has recognized and begun
to focus on MIC.
terminal at the McCarran International Airport, Las Vegas, Nev., was
experiencing an unusually high number of pinhole leaks in its fire
sprinkler system. During the course of repairing these pinhole leaks
in the less than 10-year-old system, airport technicians noticed a
significant amount of internal buildup of tuberculation nodules in
the system piping. This internal buildup caused concern over the system's
ability to perform to its hydraulic specifications. Additionally, the
possibility of the buildup breaking off and plugging the sprinkler
heads in an emergency event led the airport authority to investigate
methods of correction.
July 1996, McCarran International Airport personnel decided to use
the PIPE-KLEAN® fps (patent pending) cleaning process to chemically
rehabilitate the standpipe system in the International terminal. The
laboratory results from testing the internal buildup of the pipe samples
sent to HERC Products showed Microbiologically Influenced Corrosion
(MIC) was the culprit. High levels of iron, as well as aerobic and
sulfate reducing bacteria were present in the system.
project started with the standpipe system. Due to the non-uniformity
of the internal buildup in the system, an isolated circulation loop
was designed using a HERC patented Mobile Recirculation Unit (MRU)
to pump the PIPE-KLEAN C cleaning solution through the standpipe system.
The chemistry was circulated for approximately two hours to remove
the MIC and internal buildup. The PIPE-KLEAN fps process calls for
the monitoring of specific gravity, pH and total dissolved solids during
the cleaning process to track the cleaning progress. A CCTV system
was then employed to scan the pipe interior to ensure that all the
buildup had been dissolved and removed. The spent cleaning solution
was then evacuated from the system, neutralized, and discharged to
the sanitary sewer with the appropriate local regulatory approvals.
HERC's PIPE-KLEAN C chemistry is a low pH, aqueous organic biocleaner
with dispersants and inhibitors that has been certified to ANSI/NSF
Standard 60 for the use in potable water systems and applications.
the successful cleaning of the standpipe system, the airport then engaged
the services of HERC's PIPE-KLEAN fps to clean the entire wet sprinkler
system in the International terminal in March 1998. A joint effort
of Grinnell Fire Protection Systems Company's Las Vegas, Nev. office
and HERC Products was planned to clean the fire protection system of
the terminal, which consisted of four separate systems with a combined
total of over 1600 sprinkler heads. Due to the passenger traffic, the
cleaning schedule was limited to a 48-hour window, beginning Monday
at midnight and concluding Wednesday at midnight each week.
draining the system and protecting the work area, each sprinkler head
was removed and replaced with a valve assembly attached to plastic
hose with connections to a series of manifolds. These manifolds were
connected to the patented MRU, which pumped the PIPE-KLEAN® C cleaning
solution through the isolated system. Over 300 sprinklers were removed
during each 48-hour cleaning schedule. Once the cleaning process was
complete, the sprinkler heads were cleaned and reinstalled.
order to control MIC, some type of post cleaning water management is
necessary. McCarran opted to work with their contracted chemical supplier
to treat the water used in their fire protection system with a non-oxidizing
is one case in which the effects of MIC have been mitigated. Using
HERC's process, McCarran was able to remove the MIC presence from the
entire fire protection system in their International terminal in only
240 hours over a five-week period.
Note: HERC Products Inc. is based on Phoenix, Ariz., and can be reached
Figure 1: HERC's patented Mobile Recirculating Unit allows the cleaning
chemistry to circulate through the system.