Putting Together
A Rack Job
Scope of Responsibility
Wireway/Husky is a member of the Rack Manufacturers Institute of the USA. Wireway/Husky fully endorses the 'Specification for the Design, Testing, and Utilization of Industrial Steel Storage Racks - 2001 Edition'. Wireway/Husky requires all of its equipment be used within the parameters of the above stated specification.
It is the responsibility of any user of this manual to ensure that their unique and specific design application corresponds in the first instance to this Specification, and to any other local or national codes and/or regulations that may be applicable. The descriptive guidelines offered at various points in this book are just that, guidelines; and are only offered as a starting point for the general education of any user of this book. Any user applying these guidelines without reference to both the Specification and full knowledge of the individual application, national/local codes, and all applicable regulations do so at their own risk.
Step 1. Find
out everything there is to know about the item you are
handling/storing. Find out the three-dimensional size and weight of
every load and pallet going to any location. Remember that the
pallet may not be exactly the same size as the load, there may be
overhang one way or the other. Also be careful to ask about the
quality of the bottom of the pallets and whether or not they are
capable of resting on just beams. If they are broken or rotted, they
might require wire deck to safely support them.
Step 2. Find
out everything there is to know about the area that the rack is
going to be installed. Start with the physical dimensions of the
available space. Next the floor condition, its load bearing capacity
and any slope. Find out about the available clear headroom and the
presence of any overhead or other obstructions. Find out if there
are any access-ways that the rack must not obstruct. Column
centerlines and size are also important for flue space specification
and layout information.
Step 3. Find
out the method to be used for storing and retrieving loads in the
rack (often Fork Truck or Pallet Jack). Can it carry the proposed
load? What is its width and right angle turn dimension? What is its
maximum lift height? Remember you must subtract from this number,
usually 6", for most pallets to be lifted clear of the beam.
Take note of anything else that might impede on its safe interaction
with the rack.
Step 4. Select
the beam. First decide how many loads should be on each beam level.
The length of the beam can be determined by adding three inches to
either side of the pallet, (or load, whichever is largest), and
multiplying by all the loads on the beam. For example, a load/pallet
of 42" width, two to a beam = 42" +3" +3",
multiply by 2 and this comes to a 96" beam. The 3"
additions are to give adequate side clearance for loading and
unloading. The model of beam should then be selected from the 'Beam
Selection Chart' below, making sure that the loads do not exceed the
maximum capacity. If the beams are longer than 120" they should
be tied across the middle to prevent beam spread. If loose decking
is to be used, any pair of beams over 90" in length should be
tied across the middle for the same reason.
Step 5. At
this point ALWAYS start a sketch of each individual bay, no matter
how small the job.
Step 6. Figure
out how many beam levels you will have in any bay. Are the first
pallets/loads going to sit on the floor, or on a set of beams? To
calculate the number of levels add together the pallet and load
height plus 6" for clearance. Add the face/height of the beam
you just selected for the overall total. Fit as many levels as
possible in the height available remembering to make sure the fork
truck is able to lift the pallet off the top beam with it's maximum
fork height capabilities. It usually needs an additional 6-8"
of lift height over the top beam. Finally make sure there is enough
clearance for any sprinkler requirements.
Step 7. A. Figure out the frame capacity necessary. Add up
all of the beam loads acting on the frame, then work out the largest
pallet opening on the frame (usually floor to first beam, but
occasionally beam to beam above that). Loads on either side of the
frame up to the center points of the beams, act upon the frames.
Note that in the illustration below there is 15,000 lbs. acting on
the middle frame. Now, using the capacity chart shown on page 4,
select the appropriate frame model. B. Figure out how high
the frame needs to be to reach the top of the top beam. In most
applications you should then add between 6" and 18" (up to
the next standard frame size) to allow for flexibility in
installation. If the customer wants the frame flush with the top of
the top beam, be very sure to check the load dimensions again very
carefully and check the floor for the possibility of slope in both
the 'cross-aisle' and 'down-aisle' directions. C. Figure out
how deep the frame needs to be. The dimension of the pallet
determines this. In most applications an overhang of 3" on
either side of the pallet is desirable (if the pallet is 48"
deep the frame should be 42"). If the application demands that
the pal-lets be flush with the front and back faces of the rack bay,
cross supports from beam to beam MUST be used. The cross supports
may be crossbars or wire deck.
Step 8. Now put together your final sketch showing all the
bays that go together to make up a row, and count up all the beams
and frames you need for the sys-tem.
Step 9. Is your system a single row? Or will it be
installed 'back-to-back' with another row of rack? If it is
back-to-back, it should be tied across the 'flue space' in the
middle with row spacers. You should always use a minimum of two row
spacers no matter the height. You should also ensure there is not a
gap greater than 10' in height between row spacers, adding a third
or fourth one if necessary.
Step 10. You must now check to see whether your system is
stable or not. First, check the height com-pared to the depth for
overturning stability. To do this, find the height from the floor to
the top of the very top-most beam. Now, divide that figure by
either, the depth of the frame (if this is a single row); or, the
depth of both frames plus the row spacers (if this is a back-to-back
row). Is the answer to your division sum larger than 6.0? If so you
will need to call your Husky representative for assistance, as the
system is unstable. Second, check for rotational stability. Do
you have only a single beam level between frames in a bay anywhere?
If so you will need to call your Husky representative for
assistance, as this system also is unstable.
General. General Pallet rack installations are structurally
engineered systems that carry heavy loads. The steps above give a
guideline for the safe specification of components for simple
cases where conditions are perfect. They are written with regard
to RMI 2001 which is the guiding industry specification at time of
publication. If, in the future, this specification is revised or
overridden; or, if you have any doubt or confusion whatsoever
about any of the steps above, please contact your Husky
representative for assistance.
Final. Please remember that your system should be
shimmed level and anchored to the floor (one anchor per leg).
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