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Description  |
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BACKGROUND
This application relates generally to fireproofing products and more
specifically to fireproofing panels.
Fireproofing is an important segment of an overall fire protection system
to protect people and property. The fireproofing is applied over some type
of substrate. Typically, fireproofing is applied to structural members in
areas where a fire can occur. In the event of fire, fireproofing will
retard the rate of temperature increase in the structural members such
that the failure temperature of the members can be delayed for as much as
several hours. During the period of delay, the fire may be extinguished
or, at the least, the structure can be safely evacuated. When no
fireproofing is used, structural members have been known to fail, thus
resulting in structure collapse, in less than 15 minutes.
Fireproofing is also applied to elements such as walls, bulkheads, or
decks. In a fire, the fireproofing delays an increase in temperature
behind the element. Where flammable material is stored behind the element,
the fireproofing can prevent ignition of the material, hopefully until the
fire is extinguished.
Fireproofing is also applied to pressure vessels. The fireproofing reduces
the possibility that the vessel will rupture. Thus, the fireproofing
reduces the chance of explosion or release of hazardous material from the
vessel.
Fireproofing is also used over cable trays. The fireproofing can keep the
circuitry in the tray functioning for an extended period of time in the
event of a fire.
One widely used type of fireproofing is a char-forming coating. The coating
can be called ablative, subliming, or intumescent. As supplied, these
coatings can be in the form of a low viscosity paint or a high viscosity
mastic. These coatings are sprayed or troweled or brushed on to a
substrate.
Some of these coatings are used in combination with a mesh element. Some
coatings utilize a flammable mesh, others a non-flammable mesh such as one
fabricated from steel. With some coatings, the mesh is mechanically
mounted on the substrated; with others, it is simply embedded in the
coating.
When these coatings are exposed to a fire, they undergo a number of changes
of state--solid to liquid, liquid to gas, and solid to gas--absorbing some
of the energy of the fire, and insulating the substrate. Fire exposure
results in the formation of a char which, depending on the material, can
be thicker, as thick, or less thick than the thickness of the non-fire
exposed coating.
The above-mentioned mesh element may perform one or more functions. Mesh
might be used to retain char on the substrate. It might be used to retain
the fireproofing material on the substrate before a fire even if the
fireproofing material adheres to the substrate. In other instances, the
mesh reinforces the fireproofing prior to a fire to reduce damage to the
coating of fireproofing which could be caused by impact or movement of the
substrate.
One example of a fireproofing compound which forms a char is CHARTEK
intumescent epoxy coating sold by Textron Specialty Materials of Lowell,
Mass., USA. Other such materials are described in U.S. Pat. No. 3,849,178,
issued to Feldman.
It has been suggested that the cost of installing fireproofing could be
reduced if the substrate were covered with fireproofing panels. Panels
could be installed without the special equipment needed to apply coatings
of fireproofing material. Also, surface preparation needed before a
coating can be applied could be eliminated if panels were used. Further, a
coating can be applied to an outside structure only if weather conditions
are favorable while the coating is applied and is curing. Installation of
panels is much less dependent on weather conditions.
Panels made of fireproofing material similar to concrete are commercially
available. For example, U.S. Pat. No. 4,567,705, to Carlson describes such
panels. To protect a substrate, steel studs are welded to the substrate in
a predetermined pattern. The stud positions match holes in the panels. The
panels are then mounted on the studs and bolted to the substrate.
To cover a substrate larger than a single panel, many panels are mounted to
the substrate. The panels are butted together. The space between the
panels is caulked to provide a barrier to moisture. The panels are,
however, very heavy and are difficult to install in some places. Also,
such panels are not used where the fireproofing must have an A or a H
rating.
Lightweight pieces made from char forming compounds have also been
suggested. U.S. Pat. No. 4,493,945, shows lightweight pieces of
fireproofing material used to cover a substrate. Relatively complicated
fastening mechanisms are employed. Morever, it is necessary to still use
char-forming compound in its liquid (mastic) form to seal the seams
between pieces.
The pieces shown in U.S. Pat. No. 4,493,945, have also been formed as
panels. The panels are attached to walls or large substrates by bolting
them to studs mounted to the substrate. The joints between panels and the
bolts are then covered by a char-forming compound in liquid form.
Such a system could be improved in several ways. First, the need to seal
seams with fireproofing material requires favorable weather conditions,
which is one of the disadvantages of the sprayed-on and troweled-on
mastics. Also, metal studs conduct heat to the substrate. If adequate
precautions are not taken, the studs might conduct enough heat to the
substrate during a fire to damage the substrate. Even where no damage to
the substrate occurs, the studs may conduct enough heat to make hot spots
on the substrate. These hot spots prevent the fireproofing system from
qualifying for an A or H fire rating. Also, the panels must be carefully
installed to keep the joints between panels very small. Even with careful
installation, the seams represent weak points in the fire protection which
may fail in an explosion or if exposed to a burning gas jet. Such causes
of stress on the joints are likely to occur during a fire. Even with no
particular stress, the joints between panels may open as the fireproofing
material of the panels undergoes state changes in a fire.
SUMMARY OF THE INVENTION
With the foregoing background in mind, it is an object of this invention to
provide fireproofing panels which can be easily installed.
It is also an object to provide fireproofing panels which can cover a large
substrate with improved seam integrity.
It is also an object to provide fireproofing panels which can be secured
together with exposed fasteners.
The foregoing and other objects are achieved in a system of panels molded
from char-forming coating. The panels are molded to interface at lap
joints. The joint portion of each panel contains a sheet of metal mesh
embedded in the char-forming material. To join panels, they are pushed
together to form a lap joint and the metal mesh sheets of the two panels
are held together by a screw.
In one embodiment, the panels are mounted to a substrate by first screwing
a sublayer comprising a corrugated element to the substrate. The panels
are then affixed to the corrugated element with exposed fasteners.
In another embodiment, the panels are cut to the width of a structural
member. Several panels are joined along one surface of the structural
member using lap joints. Panels on adjacent faces of the structural member
are joined using an angluar piece of stainless steel screwed to the panels
on adjacent surfaces.
According to another feature of the invention, a sheet of aluminum foil is
pressed into the back of each panel during molding. The aluminum foil acts
as a radiation shield during a fire to further protect the substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood by reference to the following more
detailed description and accompanying drawings in which
FIG. 1 is an isometric view of a fireproofing panel, partially cutaway;
FIG. 2 is a cross sectional view of a mold used to form the panel of FIG.
1;
FIG. 3A is a cross sectional view showing a mounting arrangement for panels
as shown in FIG. 1;
FIG. 3B is a cross sectional view showing an alternative mounting
arrangement for panels as shown in FIG. 1;
FIG. 4 is a cross sectional view of a panel constructed according to an
alternative embodiment of the invention; and
FIG. 5 is an isometric view of a mounting arrangement for the panels of
FIG. 4.
DESCRIPTION OF PREFERRED EMBODIMENT
FIG. 1 shows a fireproofing panel 10 fabricated according to the invention.
Fireproofing panel 10 is molded from a known intumescent fireproofing
coating material which will convert to a char upon exposure to a fire.
Fireproofing panel 10 has a ledge 12 along two edges. There is an overhang
14 along the other two edges. When two fireproofing panels are placed side
by side with the same orientation, ledge 12 of one panel and overhang 14
of the other panel interlock to form a lap joint.
Embedded in fireproofing panel 10 is a wire mesh 16. Here wire mesh 16 is
an open mesh with a one half inch by one half inch (12.7 mm by 12.7 mm)
opening formed from 19 swg wire. Wire mesh 16 reinforces the cured
fireproofing material before a fire. During a fire, mesh 16 reinforces the
char once it forms. Of course, other sizes and types of mesh could be used
for these purposes.
Also embedded in fireproofing panel 10 is a second piece of mesh. Here,
that mesh is perforated metal 18. Unlike wire mesh 16, perforated metal 18
is disposed in only a portion of fire protecting panel 16. Namely,
perforated metal 18 is disposed only in ledge 12.
When fireproofing panel 10 is mounted to protect some substrate (not shown)
from fire, front surface 20 faces away from the substrate. When multiple
fireproofing panels are mounted to form lap joints, perforated metal 18 of
one of the panels will always be at the rear of the lap joint. A screw
(screw 58, FIG. 3A) through the lap joint applied from front surface 20
will pierce wire mesh 16 of one panel and firmly engage perforated metal
18 of the other panel. Thus, the two panels will be held tightly together
at the lap joint by the screw (screw 58 FIG. 3A).
For the lap joint to be held together, perforated metal 18 must be strong
enough to anchor screw 58. Here, 22 guage perforated metal with 3/32" (2.4
mm) round holes on 5/32" (4.0 mm) centers is used. Other perforated metals
could be used, but perforated metal no less dense than metal with 3/16"
(4.8 mm) holes on 1/4" (6.4 mm) centers is preferred. If more dense
perforated metal is used, there must be enough holes in the perforated
metal to allow the fireproofing material to flow through the perforated
metal during molding and ensure that perforated metal 18 is strongly
bonded to the panel.
Turning now to FIG. 2, a mold for forming fireproofing panel 10 is shown.
The mold is formed on a table or other suitable base 30. Angle brackets 32
are mounted to table 30. Screws, clamps or any convenient mounting means
could be used. Angle brackets 32 define the boundaries of fireproofing
panel 10. Fireproofing panels are made to any convenient size. Here, the
panels are squares roughly three feet (0.9 m) on a side. Thus, angle
brackets 32 are mounted to table 30 to form a three foot square.
During fabrication, shoulder 34 is placed into the mold along each edge
which will have a ledge 12 (FIG. 1). Shoulder 34 is made from metal,
plastic, or wood and secured in place by pin 38, or by some other
convenient method such as screws. The pieces of the mold are coated with a
commercially available mold release product.
Next, spacer blocks 112a and 112b are placed in the mold. Spacer blocks
112a and 112b hold mesh 16 away form surface 20. The thickness of spacers
112a and 112b is not critical. They should be approximately half the
thickness of the finished panel.
As spacer blocks 112a and 112b become part of the finished panel, they are
made from fireproofing material. The fireproofing material can be molded
into the desired sizes of spacer blocks 112a and 112b. Alternatively, it
can be molded in a sheet and cut to the right size after curing. A
suitable material is also described in U.S. Pat. No. 4,529,467, but many
commercially available fireproofing products are acceptable.
Next, a fireproofing material is poured into the mold until the
fireproofing material comes roughly to the top of shoulder 34. The
material is any known fireproofing material which is conventionally
applied in a liquid state and then cures to an epoxy.
Next, wire mesh 16 is laid into the mold. Also, shoulder 36 is placed into
the mold and held in place by pin 40. Shoulder 36 holds one edge of wire
mesh 16 in place.
A shoulder 36 is placed along each edge which does not already contain a
shoulder 34. The portion of panel 10 under shoulder 36 forms overhang 14.
Next, more fireproofing material 44 is added to the mold to cover wire mesh
16. Perforated metal 18 is placed into the mold over shoulder 34. Pin 42
is inserted to ensure perforated metal 18 remains embedded in the
fireproofing material 44. The mold is then filled with fireproofing
material to the top of shoulder 36.
The fireproofing material 44 is then smoothed by trowelling or by vibrating
table 30. The fireproofing material 44 does not need to be completely
smooth since the surface at the top of the mold will be mounted facing a
substrate and will not be visible. In contrast, upper surface 20 (FIG. 1)
is the surface against table 30. That surface will be smooth.
The fireproofing material is then allowed to cure. The material might be
allowed to air dry or the curing could be accelerated by placing the
entire mold in an oven. When cured, the panel can be removed from the
mold.
Turning now to FIG. 3A, a method of mounting several panels to protect a
large substrate is shown. FIG. 3A shows a portion of a substrate 50
protected by fire protecting panels 10a, 10b, 10c.
To mount fire protecting panels 10a . . . 10c, a layer of corrugated
material is screwed to substrate 50. Here, 0.7 mm galvanized steel roof
decking with profile D38A is used.
Roof decking 52 is secured to substrate 50 via screws 54. Here, TRAXX
4-12/24.times.22 mm screws are used. It is important to note that no
special insulation or heat treatment is needed to prevent screws 54 from
transmitting excessive heat to substrate 50. Screws 54 are behind panels
10a . . . 10c and are thus thermally protected.
Next panels 10a . . . 10c are screwed into place with screws 56. Screws 56
must be long enough to pass through a fireproofing panel 10 and roof
decking 52. However, screws 56 must not be so long that they contact
substrate 50. Here, No. 12.times.25 mm stainless steel sheet metal screws
are used.
Screws 56 are used with stainless steel washers (not numbered) such as 4
mm.times.25 mm washers. Any size washer preferably larger than the
openings in mesh 16 can be used.
A sufficient number of screws must be used to secure panels 10a . . . 10c.
Here, 9 screws per panel are used, or roughly one screw per square foot.
After the panels are secured, the lap joints between panels are firmly
joined. Here, screws 58 with washers (not numbered) are used. Screws 58
are identical to screws 56. It should be noted from FIG. 3A that it is not
crucial whether screws 58 pierce roof decking 52. Screws 58 must simply
engage perforated metal 18 within ledge 12 (FIG. 1). Perforated metal 18
(FIG. 1) provides adequate support for the lap joints between panels.
Screws 56, however, must be installed into a ridge of roof deck 52.
During installation, the lap joints may be caulked to prevent moisture from
seeping behind panels 10a . . . 10c. This step is only important when
panels 10a, 10b, 10c are exposed to moist environmental conditions.
However, any type of caulking, such as silicone caulking, can be used.
Special fireproofing caulking is not required.
From the foregoing, it will be appreciated that the fireproofing system of
FIG. 3A is easily installed. Corregated roof decking 52 can be quickly
installed with self tapping screws. Exact positioning is not required.
Special tools are not required. Panels 10a, 10b, 10c, etc. are easily
installed to the roof decking. The ridges of roof decking 52 preferably
run vertically up a wall or other substrate. Thus, screws 56 are installed
in vertical lines up the wall. Because of the width of each ridge in roof
decking 52, exact placement of screws 56 is not required. Positioning of
the panels is simply accomplished by pushing the panels snugly together to
form the lap joints. No posts and holes are required.
Also, screws 56 can be left exposed. As shown in FIG. 3A, a thermally
conducting path from screw 56 to substrate 50 includes not only screw 56
but roof decking 52. Thus, even if screw 56 gets very hot in a fire,
little heat is conducted to substrate 50. Thus, the panel system shown in
FIG. 3A can qualify for an A or H fire rating.
Turning to FIG. 3B, the invention in another mounting arrangement is shown.
In FIG. 3B, substrate 70 is a deck or a ceiling with supports 72. In steel
structures supports 72 are beams spaced by a large distance, say eight
feet. To install panels, sheets of roof decking 52a . . . 52d are screwed
into supports 72. Then, panels 10a . . . 10j are screwed into the roof
decking as in FIG. 3A and the lap joints are screwed together.
It will be appreciated that installing panels in this fashion is relatively
easy since the panels are of a size which can be easily manipulated.
However, joints and screw holes do not have to be filled with fire
protecting material, which would be very cumbersome to apply to a ceiling
or the underside of a deck. Also, the area of the surface covered by
fireproofing is reduced over what would be required if fireproofing were
sprayed onto deck 70 and supports 72.
Turning now to FIG. 4, an alternative embodiment of the invention is shown.
The embodiment of FIG. 4 is useful to cover structural members. FIG. 4
shows in cross section a fireproofing panel 110. As described above, panel
110 is molded from a commercially available fireproofing material. Here,
no wire mesh is employed. Rather, perforated metal sheet 114 extends
throughout the entire panel. Perforated metal sheet 114 is as described
above.
During molding, perforated metal sheet 114 is held away from upper surface
20 by spacers such as spacer blocks 112a and 112b. Here, spacer blocks
112a and 112b are made of the same fire protecting material used to form
panel 110.
It should be noticed that blocks 112a and 112b are of different thickness.
The thicknesses of the spacer blocks 112a and 112b are selected to keep
perforated metal sheet 114 as far from front surface 20 as practical but
to still have it embedded in the fireproofing material forming panel 110.
Spacer blocks 112a and 112b are placed in the mold before fireproofing
material is poured into the mold.
FIG. 4 also shows a feature which can be added to the fireproofing panels
made according to the invention. FIG. 4 shows a sheet of aluminum foil 116
on back surface 22 of panel 110. Here, aluminum foil 116 is approximately
0.00475 inches (0.12 mm) thick. It is attached to panel 110 while it is
still in the mold and before the fireproofing material of the panel cures.
During molding, aluminum foil 116 can simply be placed over the mold and
rolled into the surface of the fireproofing material before it cures.
In a fire, some hot gases and heat may penetrate panel 110. However,
aluminum foil 116 does not readily emit heat toward the substrate
protected by panel 110. Also, aluminum foil 116 reduces the amount of gas
which penetrate panel 110. Thus, foil 116 can reduce the amount the
substrate heats up in a fire.
FIG. 5 shows how panels 110 might be used to protect a structural member
120 from fire. Panels 110a . . . 110f are shown to have the same width as
structural member 120. This width can be achieved by molding panels to any
convenient width and then cutting them, using a saw, to the appropriate
width. Of course no lap joints are needed on the edges of panels which
span the width of structural member 120. Thus, no ledges or overhangs are
formed on those edges during molding.
To span the length of a beam, several panels 110 are joined with lap
joints. As before, those lap joints are secured with screws 124.
To secure panels 110 on adjacent sides of structural member 120, angle
braces 128a-128c are used. Here, 20 gage 11/2".times.1" (38 mm.times.25
mm) stainless steel angle is used. Angle braces 128a-128c are secured to
panels 110a-110f using screws 122a-122o (only selected screws shown). A
minimum spacing of 8" between screws is preferred. Here, 3/4" (19 mm)
stainless steel sheet metal screws are used. The length of these screws is
selected to be roughly the thickness of panels 110a-110f.
It will be appreciated that screws 122a-122o may contact structural member
120. However, little heat will be conducted to structural member 120.
Screws 122a-122o end in a point 126, as is common for sheet metal screws.
Thus, the total area of screws in contact with structural member 120 is
small and heat transferred to structural member 120 is correspondingly
small. Thus, screws 122a-122o do not need to be coated with fire
protecting material.
By applying panels as shown in FIG. 5, all joints between panels are either
covered by angle brace 128 or form a lap joint. The lap joints 130 and
butt joints 131 may be caulked to provide a seal against weather
conditions. Otherwise, no special sealing of joints is required.
As shown in FIG. 5, panels 110a, 110b, and 110c are mounted with open
spaces in structural member 120 behind them. However, this mounting
arrangement is acceptable. Perforated metal 114 (FIG. 4) provides adequate
structural support. Aluminum foil 116 prevents hot gasses from penetrating
into the open space during a fire.
In a fire, aluminum foil 116 may separate from the back of the panels. Foil
116 will, however, remain in place. For panels such as 110c and 110d which
contact structural member 120, foil 116 is held in place because it is
pressed against support member 120. For panels such as 110a and 110c, foil
116 may separate from the panels and billow into open space in support
member 120. However, foil 116 will be anchored at its ends by contact with
panels 110d and 110f and support member 120.
Having described embodiments of the invention, one of skill in the art will
recognize that variations can be made without departing from the
invention. For example, perforated metal 18 could be extended throughout
the entire area of panel 10. In this way, a panel could be cut to any size
and still have perforated metal along its edges to allow screw attachment.
Extending perforated metal 18 throughout the entire panel adds mechanical
support to the panel. This added support can be important to allow the
panels to work in situations where flame jets are expected, such as
represented by the SOFIPP test conventionally used to rate fire protecting
systems. Angle braces to join panels such as shown in FIG. 1 could be
used. Also, aluminum foil could be used to back panels as shown in FIG. 1.
Further, panels could be molded in many shapes. The panels could even be
molded to conform with curved surfaces.
Also, foil 116 need not be attached to a panel. Foil may be attached
directly to a structural member. Panels would then be installed over the
foil. Alternatively, fire protecting material could be sprayed on over the
foil.
Also, panel fabrication using conveniently available fireproofing compounds
was described. These materials contain fiberous material and epoxy.
Varying the amount of fibers and epoxy may result in materials which are
better suited to a particular molding operation. For example, the amount
of fibers might be reduced on the order of 25% from the quantities
described in U.S. Pat. No. 4,529,467.
Additionally, FIG. 3B shows panels applied to span spaces between
structural members supporting a deck. The panels could be applied in a
like fashion to cover a wall or other element with structural members
attached to it.
Also, molding was described as comprising pouring fireproofing material
into a mold. It might be sprayed into the mold or applied in other ways to
facilitate rapid molding of panels.
Accordingly, the invention should be limited only by the spirit and scope
of the appended claims.
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