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May 2006
MATERIAL
INTRODUCTION
Fiber Reinforced Composite (FRC) materials and their use are
common to the electric power industry.
Many products used by the industry that are fabricated of
FRC materials include ladders, grating, construction tools,
lift-truck booms, transformer pads, hot sticks, bus bar supports,
insulators, pole line hardware, and crossarms. Over the years,
pole structure design advancements utilizing FRC materials have
become the material of choice for usage in lighting,
telecommunication and power distribution systems. PFRC (Pultruded
Fiber Reinforced Composite) materials are used widely in many
applications because they can be engineered to offer important
advantages over traditional materials.
Such advantages include reduced weights, a high
strength‑to‑weight ratio, low maintenance, dimensional
stability, high dielectric strength, non-toxic handling &
service life, resistance to rot, corrosion, chemicals, pest damage
and non-toxic disposal. PFRC
materials and processing also offer product designer much
flexibility. Engineers
can choose from a wide range of material fiber and resin systems
to configure a product to the end use specifications.
This degree of flexibility distinguishes PFRC materials
from "traditional" materials such as wood, steel or
concrete. The benefits
and limitations of PFRC products depend on the materials
selection, manufacturing processes, fabrication techniques and
handling procedures of the product from the manufacturer’s
factory to the field installation.
This document discusses such topics to assure a
Powertrusion PFRC Pole is safely installed to service with much
success.
POLE
STRUCTURE DURABILITY
PFRC
poles are more resistant to many environmental factors than poles
made of other materials. The
most common environmental factors include wind, rain and sunlight.
Other conditions, such as soil type, area maintenance
(weed-trimming, etc.), human and animal interaction, chemicals and
vandalism, can affect the durability of the structure.
Described below are various actions taken with PFRC
material systems to maximize the capability of structures to
withstand the affects of prolonged exposure to the environment.
Chemical
Exposure & Biodegradation
PFRC
products are naturally resistant to most chemicals found in
subterranean and outdoor environments.
PFRC pole materials are not biodegradable.
They are not susceptible to termite, woodpecker, or other
biological attack. The
material is inert and can be disposed of in normal non-hazardous
landfills. PFRC poles are inherently resistant to long-term
degradation effects of soil conditions, fungi, insects, bird
attack, and corrosive environments.
If the user has a concern with a specific chemical used in
conjunction with the pole, please notify Powertrusion for addition
confirmation.
Ultra-Violet Light Protection
Ultra-violet
light could possibly cause color fading and degradation to the
pole materials. Advances
in material science have produced very effective life-extending
protective systems. The POWERTRUSION pole uses three levels of
protection against ultra-violet light to enhance the service life
of the structure. The
protective system includes a multitude of UV inhibitor materials
co-mingled to the base resin, a resin-rich non-structural surface
veil, and an UV stable pigment additive to provide color. The
pultrusion process efficiently provides a resin-rich surface on
the product loaded with the UV inhibitors.
In addition, the exterior surface of the pole is enveloped
with a synthetic corrosive resistant veil material to enhance the
resin rich pole surface. By
doing this, the actual structural fibers are buried beneath a
layer of non-structural resin.
Because the resin itself is loaded with a UV inhibitor, the
load-carrying fiberglass is afforded significant protection. Powertrusion
has implemented significant changes to its base resin chemistry
and UV absorption additive package creating a synergistic effect
among the collective group of materials. The improved UV additive
package increases the protection of the resin rich, veil surface
as well as increases the UV protection throughout the
cross-sectional thickness of the pole.
Due
to the nature of the PFRC materials and the importance of the pole
surface to provide longevity to its design and function,
reasonable care needs to be taken with attention to shipping and
handling procedures from the manufacturing facility to time of
pole’s installation to service.
Listed below are procedures and practices to be followed in
handling PFRC products.
TRANSPORTATION
and HANDLING
Shipping & Receiving
PFRC poles can be transported in the same manner as poles
made of other materials. Over
long distances, flatbed and LTL haulers can be used.
There is a need to limit road hazard damage to a very
minimum.
The
user should review Powertrusion’s methods and procedures for
packaging and shipping of PFRC products as shown in drawing
specification PT-3-10-08 (two pages). This specification explains
the bundling of multiple poles to a single shipping crate and the
loading & securing of multiple bundles to transportation
equipment. The PFRC poles are tubular and NOT solid cross
sections; care must be given to the tightness of the tie-down
straps securing the bundles to the transportation trailer. Poles
bundles will be shipped to facilitate loading & unloading with
a forklift. Any special customer requirements for method of
packaging, delivery mode, destination or notification should be
clearly defined in the purchase order agreement.
It is the practice of Powertrusion to photograph material
after it is loaded, secured to the transportation equipment and
ready for over-the-road travel. It is strongly recommended that
user (or responsible party receiving the material) follow the same
practice of photographing the material upon receipt for
documentation and record keeping.
When receiving products per order agreements, the user is
also responsible for ensuring that all materials, hardware and
fittings are accounted for as listed on bill of lading and / or
packing sheet. When a
discrepancy occurs, both the manufacturer and the carrier should
be notified.
When receiving PFRC products, all items should be inspected
for damage prior to acceptance.
If damage has occurred, the user should immediately notify
the delivering carrier or the manufacturer, whichever is specified
by the purchase order agreement prior to any actions taken to
unload the material from the transport equipment. The user should
notify the manufacturer of any damage and then cooperate in filing
damage claims with the carrier.
The damage report should also indicate what types and level
of damage that has occurred to the material. Powertrusion must to
be notified to discuss the reported damage to make assessments to
the structural integrity of the material for its intended use.
It is important that rejection criteria be established and
agreed to by both the user and the manufacturer prior to
fabrication and delivery of the order.
A clear and concise definition of what will constitute
ground for rejection of PFRC products should be included in the
purchase order agreement.
Storage
PFRC poles can be stored outdoors or indoors.
Poles are delivered in bundles to assist in yard storage
and minimize pole handling and movement prior to actual delivery
to job location. To avoid unnecessary damage to the pole surface,
use a similar cribbing plan to store poles so that they are
separated from one another if it is necessary to unpack the poles
from the original shipping crates.
The timber or cribbing should also keep the pole high
enough above the ground to allow lifting straps to be easily
slipped under and around the pole. If stacking poles in more than
two layers, consideration should be given to the potential mass of
the cribbing and stacking weight to oval the bottom poles.
FRC poles that are stored horizontally for long periods and
allowed to sag will return to their original shape when erected as
the resin material is a thermosetting chemistry and does not
creep.
Handling Instructions
Powertrusion PFRC poles are lightweight and an important
consideration is that poles are much lighter in weight than poles
made of other materials. However,
the user should have a general understanding of the weight of the
structure and ensure that proper equipment is available for
installation. The identification tag contains the estimated weight
of the pole. Contact Powertrusion to verify any weight issues on
specific products. This weight differential means the user may be
able to use lighter duty equipment and anticipate minor
adjustments in lift balance points.
PFRC poles can be loaded/moved/unloaded using a forklift
positioned perpendicular to the longitudinal axis of the pole and
with the load in balance. Care should also be taken in handling to
prevent puncturing or cracking a pole with the forklift and to
prevent damaging the UV surface. It is important to fully position
the forklift under the load and lift the pole(s) rather than
“slide” the forklift across the flat surface of the pole while
in a lifting action. All fiberglass poles can be handled utilizing
single pick points. The center of gravity on an unframed pole is
typically at mid-point of the overall length due to its non- taper
design. Significant hardware installations will affect the balance
and location of pick when moving a pole, the user should evaluate
these weights and adjust the pick point accordingly.
Nylon slings should always be used in lieu of chains,
cables or other metal hardware when lifting PFRC poles. Poles may
also be handled with a crane using a two-point pickup system with
nylon slings or combination spreader bar with nylon slings
attached to the pole(s). The
minimal weight of the pole should eliminate the need to drag or
skid the pole for any significant distance. If dragging of the
pole is necessary for extended lengths due to difficult terrain,
the butt of the pole should be protected to avoid excessive damage
to PFRC materials and butt plate. PFRC poles are NOT solid cross
sections. Care should be taken in the lowering of the pole to the
ground to facilitate the removal of the handling slings. Poles
should not be dropped from distances or freely dumped from
transportation trailers. Poles should be rested to a firm surface
with clearance allowed to easily remove the supporting slings.
For short distances, pole dollies and other pole handling
vehicles can be used. If
pole dollies are used, nylon straps should be used in lieu of
metal chains to secure the pole.
Because FRC poles are lightweight, some distribution size
poles can be manually carried short distances between the staging
area and the installation site. Craft persons using shorter nylon
slings utilizing the sling openings as handles can carry PFRC
poles. Pole climbing hardware is also a means of
“handling” a pole for manual carry.
Framing
Most standard, non-cleat line hardware can be used on PFRC
poles with conventional fasteners and practices.
In general, the
POWERTRUSION pole will accept most of the hardware that is used on
a wood, steel, or concrete pole.
However, washers that conform to the pole surface
should be used beneath the bolt head and nut. Powertrusion
recommends flat washers be used for all installations at minimum
dimension of 3” x 3” to enhance the load bearing surface of
the hardware to PFRC materials.
The preferred
method of attachment is with through bolts.
The maximum torque applied to through-bolts is recommended
not to exceed 55 ft-lbs. However, the pole has been tested to
withstand torque in excess of 80 ft-lbs; results causing an oval
effect to the profile but without fiber damage to the pole.
Because the pole is not tapered, it may be necessary to place a
through-bolt either through or beneath a cluster-mounting bracket
that encircles the pole.
The following hardware features are
not compatible with the POWERTRUSION pole:
q
Lag
bolts: Use a through bolt instead.
q
Teeth: Hardware that is drawn into
a wood pole should not be used on a PFRC pole.
In almost every case, a similar piece of hardware exists
that does not have teeth.
q
Nails
and Staples:
Use self-tapping screws.
POWERTRUSION will pre-drill holes per customer
specifications. Holes
can be drilled in the field with either hardened high-speed steel
(HSS) twist drills, carbide tipped twist drills or self-centering
hole-saws. Diamond
coated hole saws, carbide tipped twist drill bits and brad-point
HSS twist drills perform best.
The number of holes needed determines drill selection.
Carbide or diamond type drills are recommended for
quantities above 20.
POWERTRUSION recommends primary holes for equipment, climbing
steps or any load bearing application be drilled on the octagonal
NON-SEAM side. The die
parting lines on (4) of the (8) sides determine a SEAM side.
It is necessary that the exposed fibers from drilling
operations be sealed to assure proper performance of the pole.
It is recommended that a polyester, acrylic, or
polyurethane resin solution be applied to the finished hole prior
to installing attachments.
Spacing of holes should be drilled on centers at least four
hole diameters apart when drilled on the same plane. For example:
three-quarter inch holes should have a minimum separation
between hole centers of three-inches.
Holes located in opposing planes need enough separate for
clearance of bolt hardware.
Any dust particles generated by a drilling or cutting process
are non-toxic and classed a nuisance dust; however, it is
recommended that user personnel adhere to the same safety
practices used when drilling and cutting other materials. Contact
Powertrusion for any further information.
Climbing
Climbing provisions are
available but vary depending upon manufacturer of the climbing
hardware. Climbing positions are usually vertically spaced every
15 to 18 in. and are oriented at 180 degrees (each side of a pole)
to each other. “Stepping” positions and “working”
positions (steps at the same elevation) can be specified by the
users and holes factory drilled by Powertrusion prior to delivery
of poles. Contact
Powertrusion for information and recommendations on climbing.
PFRC poles are generally easier to erect than traditional poles
that are heavier due to their lightweight character.
Conventional equipment and practices can be used as
required for the terrain and site conditions.
They can be erected using a single pick-up point as
determined by the weight of the pole and any framed hardware
depending upon the intended application. Nylon slings should used
by the method of “choking the sling” to secure the pole to the
lifting cable; this practice avoid scratching and gouging the pole
finish. Care should
also be taken to ensure that the top and bottom caps and all
joints and connections are secure before erecting the structure.
Direct
Embedment
Powertrusion pole design is to be directly embedded in the
ground. Because PFRC
material is inert, poles do not adversely affect the environment
and do not require special protective coatings or treatments
before being embedded. PFRC
poles can be direct embedded using the same burial depth as would
be used for most other types of poles unless special loading or
soil conditions dictate otherwise.
Once the pole is placed in the hole, the hole can be
backfilled with any material normally used, such as native soil,
crushed aggregate, concrete, or structural foam.
Backfill tools and techniques for Powertrusion poles are
typically the same as those used for poles made of other
materials. Care should
be taken to avoid impacting the pole wall with tools during
backfill and tamping operations. Similar to all tubular poles, a
bottom plug is provided to prevent further settling after the PFRC
pole is installed.
Pole
Grounding
Ground wires can be fastened to the pole with copper ground clips
and self-tapping screws. Plastic
wire molding strips can also be used to secure the ground wire to
the pole. These strips
contain the ground wire and are easily secured to the pole with
the appropriate fastener and a self-tapping screw.
Ground wires can also be run inside of the pole to
discourage theft.
INSPECTION
Visual inspection is a reliable method for surface damage
assessment of a PFRC material.
It can roughly map out an area of surface damage, but will
not necessarily reveal information about any underlying damage.
Visual inspection of PFRC structures by maintenance
personnel should include inspection for the following:
q
Tracking
on material surface
q
Lightning
damage
q
Vandalism
damage
q
Mechanical
impact damage
q
UV
– Veil surface damage
q
Delamination
or cracking evidence of composite
Items such as scratches, minor nicks and discoloration may be
visually evident, but are not considered to have a significant
impact on the structural integrity of the structure.
Tap
Test
The tap test can be used as a routine test to further check
for any suspected localized damage.
The test requires an inspector to use a small hammer to tap
all around the area of suspected damage.
This is a fast, inexpensive and easy way to roughly
evaluate the condition of the material and locate delamination,
large voids and cracks. Any area of the PFRC pole that has
suffered an impact and has internal damage will be evident by a
low – shallow sound given off by a tap test.
Adversely, areas that are unaffected and structurally sound
will be evident by a high pitch sound given by a tap test.
Repairing
A Damaged Pole
Minor surface scrapes and gouges
can be repaired with surface treatments to reestablish the resin
protective surface. It is recommended that a UV promoted polyester, acrylic, or
polyurethane resin solution be applied to the surface damage area
to seal any exposed fibers.
Fiberglass wrap systems can repair
more severe damage such as delamination caused by vehicle impacts.
Products are available in the market place especially developed
for this type of structural and cosmetic repair. These systems are
composed of fiberglass & resin materials that are very
compatible with PFRC materials of the Powertrusion pole.
Repair ability of the POWERTRUSION damaged pole needs to be
assessed prior to major repairs undertaken to assure structural
integrity for continued use. Contact Powertrusion for more
detailed information.
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