PAINTED OR BARE STEEL PIPE
RECOMMENDATION:
Non-Conductive
Rollers should be used in lieu of, or as a direct
replacement for, cast iron rolls on any bridge
main installation that is, or is going to be,
painted. This applies for both existing and new
mains. Most paints provide only a thin barrier
and are extremely susceptible to abrasion damage.
This is particularly true at each pipe to support
contact.
REASONS:
ELIMINATES THE
POSSIBILITY OF MOISTURE ENTRAPMENT.
ROLLER WILL NOT BIND
OR ABRADE THE PAINT.
MAINTAINS ELECTRICAL
ISOLATION.
|
|
The
polyurethane based Non-Conductive Rollers are best used
alone with thin coatings because they are non-abrasive
and maintain a minimum surface contact. This eliminates
any possibility of moisture collecting between pipe and
support. In addition, the Non-Conductive Rollers are
solid and do not have the same tendency to bind as the
hollow cast iron rolls. Lubricating the roller’s
stainless steel sleeve prior to inserting the axle seals
out moisture and reduces friction.
When a pipe
has a thin barrier coating the use of a FRP Shield
increases the possibility of moisture entrapment between
the pipe and shield interface. In most cases this would
aggravate any corrosive conditions located between the
pipe and FRP Shield.
|
TAPE COATED PIPE WITH CAST
IRON ROLLER
RECOMMENDATION:
A
Type# 240 Shield needs to be installed with any
factory or field applied tape. This is
particularly important when cast iron rolls are
used. The profile of cast iron rolls do not
accommodate thick barrier coatings. The tapes
change the OD of the pipe to the point it will no
longer rest in the cradle of the roll as is the
case with bare or painted pipes. Instead, the
pipe will rest on the peaks of the roll. This
situation aggravates the point loading that
normally occurs at each of the pipe’s
supports.
REASONS:
PROTECTS THE TAPE
FROM ABRASION.
PREVENTS COLD FLOW
OF THE TAPE.
ENSURES ELECTRICAL
ISOLATION.
|
|
Tape
wraps are thick barrier coating that must be protected at
each support. Without protection the tape will cold flow
as a result of being sandwiched between the pipe and its
support. Abrasion due to even minor thermal expansion and
contraction will further compromise the integrity of the
tape. Fiberglass reinforcement enables the FRP Shields to
tolerate the point loading and prevent abrasion damage by
providing a desirable weight distribution. The FRP
Shields also ensure a high degree of electrical
isolation. Unlike non-reinforced plastics, the Fiberglass
Reinforced Shields do not get brittle in the cold and are
resistant to UV degradation.
|
TAPE COATED PIPE WITH
NON-CONDUCTIVE ROLLER
RECOMMENDATION:
A
Type# 240 Shield needs to be installed with any
factory or field applied tape. This is the case
even when Non-Conductive Rollers are used. The
profile of a urethane roller is designed to
accommodate both the tape wrap and FRP Shield.
Although the Non-Conductive Rollers greatly
reduce the possibility of abrasion, the tape must
still be protected from cold flow damage. FRP
Shields prevent damage by providing the necessary
weight distribution between the pipe and its
support. This is particularly important if the
pipe becomes misaligned.
REASONS:
PROTECTS THE TAPE
FROM ABRASION.
PREVENTS COLD FLOW
OF THE TAPE.
ENSURES ELECTRICAL
ISOLATION.
|
|
When
used together, the Non-Conductive Rollers and FRP Shields
provide the best possible protection for any tape type
wrap. Unlike hollow cast iron rolls, the Non-Conductive
Rollers are solid and do not tend to bind and will not
corrode internally. The urethane composition stays
flexible even in cold temperatures. This provides a
degree of vibration tolerance which one of the primary
causes for alignment problems. Lubricating the
roller’s stainless steel sleeve seals out moisture
and reduces friction. FRP Shields maintain the
tape’s integrity against both normal and possible
abnormal loading due to misalignments and/or support
failure.
|
P.O. Box
540
Westtown, PA 19395
Phone 610-696-9220
Fax 610-344-7519
email
