High strength,
corrosion resistant HOBAS fiberglass pipes were recently installed
in Pennington, Alabama to transport acidic effluent (pH of 3 to 4)
created in operations at the pulp and paper mill. The piping
material chosen had to meet the very demanding conditions present
including low pH, elevated temperatures (average operating of 90
to 100 degrees with excursions to 140 degrees F) and shallow cover
depths with surface traffic. The HOBAS fiberglass pipe was buried
with only 1 foot of cover through frequently saturated, very soft,
native materials.
Easy Installation
The 48 inch diameter pipes have a pipe stiffness of 72 psi and are
constructed with an isophthalic polyester
structural resin and a vinyl ester liner resin. The pipes,
supplied primarily in 20 ft. sections, were field connected with
HOBAS FWC couplings. The parallel effluent lines run over 500 feet
and terminate at a fiberglass-lined manhole structure in which
HOBAS FWC couplings were laminated into the fiberglass wall of the
manhole liner. The HOBAS FWC coupling is a structural
filament-wound sleeve which is over-wrapped and mechanically
locked to an internal full-face EPDM elastomeric gasket. This
allows the coupling to maintain a leak-free seal, pipe to pipe,
with easy push-together assembly. The quick and secure field
connections with the FWC joint pleased both the installation
contractor and the plant engineers. The HOBAS installation was the
first for the paper mill and the installation contractor.
Although, the contractor admits that initially they were a little
apprehensive about installing a "fiberglass" pipe, they
were happy to find that HOBAS pipe is much stronger, tougher and
installation friendly than they anticipated.
Material of Choice
HOBAS pipes were chosen due to the need for a high strength piping
material which was also able to meet the
corrosion resistance needs of the project. Other piping materials
which were reviewed included high density polyethylene and
concrete. The HDPE did not provide adequate strength for this type
of installation due to the presence of vehicle traffic. Areas
currently exist throughout the plant where HDPE has been installed
previously which are now restricted from vehicle traffic, since
the HDPE piping material cannot handle the surface loads at such
low cover depths. This has proven to be very inconvenient. The
concrete pipe can be designed with adequate strength to meet the
loading conditions, however, it is not suitable for such an
aggressive environment. HOBAS was the only material that met all
of the engineers' criteria. With the project complete and the pipe
now on line, all parties are happy with the installation and their
decision to choose HOBAS. They are confident that HOBAS will meet
the test of time.
