Determining Pallet Maximum Working Loads From Nominal Load Measurements Marshall S. White Wilbur Dibling Ralph Rupert John McLeod
Jan 19, 2016
Determining Pallet Maximum Working Loads From
Nominal Load Measurements
Marshall S. WhiteWilbur DiblingRalph RupertJohn McLeod
Most Loads on Pallets do not act Like Airbags or Two Rigid Bars as in Draft ISO 8611-1 Tests 1 and 3
Certain Loads on Pallets will “Bridge” across the Pallet Deck.
In Warehouse Racks, Some Loads will Shift Stresses from the Center of the Pallet to the Rack Supports
We Tested Different Load Configurations To Determine The Level Of
Load Bridging In A Warehouse
Rack
We Tested The Following Load Stabilizers• Interlock Stacking
• Stretch Wrap
• Strapping (steel and poly)
• Breakaway Adhesive
• Pallet Tie Sheets
• Stretch tape
We Used Plywood To Simulate Pallets And Used 4 Different
Stiffness Levels of Pallets
5.3 kN per cm of deflection3.6 kN per cm of deflection2.3 kN per cm of deflection1.6 kN per cm of deflection
Each Load Was Lifted 5 Times To Simulate Typical Loosening
Of Load After Palletization
Case Goods, Average Deflections at 4.5 kN
Air
bag
Col
umn
Stre
tch
Tap
eA
dhe
sive
Col
umn,
SW
Tie
She
ets
Col
umn,
ST
Inte
rloc
kIn
terl
ock,
SWIn
terl
ock,
ST
Air
bag
Col
umn
Stre
tch
Tap
eT
ie S
heet
sC
olum
n,S
WA
dhe
sive
Col
umn,
ST
Inte
rloc
kIn
terl
ock,
SWIn
terl
ock,
ST
Air
bag
Stre
tch
Tap
eT
ie S
heet
sC
olum
nC
olum
n,S
WA
dhe
sive
Col
umn,
ST
Inte
rloc
kIn
terl
ock,
SWIn
terl
ock,
ST
Air
bag
Tie
She
ets
Col
umn
Col
umn,
SW
Col
umn,
ST
Inte
rloc
kIn
terl
ock,
SWIn
terl
ock,
ST
Def
lect
ion
(m
m)
0.0
5.0
10.0
15.0
20.0
25.0Low
Medium
Medium-Low
High
Case Goods, Average Deflections at 4.5 kN, Low Stiffness Panel
0.0
5.0
10.0
15.0
20.0
25.0A
irb
ag
Col
um
n
Str
etch
Tap
e
Ad
hes
ive
Col
um
n,S
W
Tie
Sh
eets
Col
um
n,S
T
Inte
rloc
k
Inte
rloc
k,
SW
Inte
rloc
k,
ST
Def
lect
ion
(m
m)
Sacks, Average Deflections at 4.5 kN
0.0
5.0
10.0
15.0
20.0
25.0Ai
rbag
Colu
mn
Colu
mn,
SW
Colu
mn,
ST
Inte
rlock
, SW
Int,
Plas
Strp
Inte
rlock
, ST
Inte
rlock
Airb
agCo
lum
n, S
WCo
lum
nCo
lum
n, S
TIn
terlo
ck, S
TIn
terlo
ck, S
WIn
terlo
ck
Airb
agCo
lum
n, S
TCo
lum
n, S
WCo
lum
nIn
terlo
ck, S
TIn
terlo
ck, S
WIn
terlo
ck
Airb
agCo
lum
n, S
TCo
lum
n, S
WCo
lum
nIn
terlo
ck, S
WIn
terlo
ck, S
TIn
terlo
ck
Def
lect
ion
(mm
)
Low
Medium -Low
Medium
High
Sacks, Average Deflections at 4.5kN, Low Stiffness Panel
0.0
5.0
10.0
15.0
20.0
25.0A
irbag
Col
umn
Col
umn,
SW
Col
umn,
ST
Inte
rlock
,S
W
Int,
Pla
sS
trp
Inte
rlock
,S
T
Inte
rlock
Def
lect
ion
(m
m)
Pails, Average Deflections at 4.5 kN
0.0
5.0
10.0
15.0
20.0
25.0Ai
rbag
Colum
n,SW
Colum
n
Colum
n, T
ape
Colum
n, S
T
Airb
ag
Colum
n
Colum
n, T
ape
Colum
n,SW
Colum
n, S
T
Airb
ag
Colum
n, T
ape
Colum
n
Colum
n,SW
Colum
n, S
T
Airb
ag
Colum
n
Colum
n, S
W
Colum
n, S
T
Defle
ctio
n (m
m)
HighMedium
Medium -Low
Low
Drums, Average Deflections at 4.5 kN
0.0
5.0
10.0
15.0
20.0
25.0Ai
rbag
Colu
mn
Colu
mn,
ST
Colu
mn,
SW
Airb
ag
Colu
mn
Colu
mn,
SW
Colu
mn,
ST
Airb
ag
Colu
mn
Colu
mn,
ST
Colu
mn,
SW
Airb
ag
Colu
mn
Colu
mn,
ST
Colu
mn,
SW
Def
lect
ion
(mm
)
Low
Medium -Low
HighMedium
Blocks, Average Deflections at 4.5 kN
0
5
10
15
20
25
30
Airb
ag
Col
umn
Inte
rlock
Airb
ag
Col
umn
Inte
rlock
Airb
ag
Col
umn
Inte
rlock
Airb
ag
Col
umn
Inte
rlock
Def
lect
ion
(mm
)
Low
Medium -Low
Medium High
The Effect of Load Geometry on Load Bridging During Warehouse Rack Storage on Pallets
Average Pallet Deflection as a Percent of Airbag Deflection
54
100 99
708287
0
20
40
60
80
100
Airbag-noload bridging
Cinderblock-column stack
Sacks-column stack
Cases-column stack
5gal pails-column stack
55gal drums-column stack
Load Geometry
Perc
ent D
efle
ctio
n
The Effect of Load Stabilizers on Load Bridging During Warehouse Rack Storage
of Cased Goods on Pallets
Average Pallet Deflection as a Percent
of Column Stacked Deflection
0
20
40
60
80
100
Column
Stacked
Stretch
Tape
Interlock
Stacked
Pallet
Sheets
Stretch
Wrap
Adhesive Strapping
Load Stabilizers
Per
cent
Def
lect
ion
100 100 8796 94
8061
The Effect of Load Stabilizers on Load Bridging During Warehouse Rack Storage
of Sacked Products on Pallets
Average Pallet Deflection as a Percent of Column Stacked Deflection
108 114100 100
020406080
100120
Column Stacked Interlock Stacked Stretch Wrap Strapping
Load Stabilizers
Perc
ent D
efle
ctio
n
The Effect of Load Stabilizers on Load Bridging During Warehouse Rack Storage
of Column Stacked 5 Gallon Pails on Pallets
Average Pallet Deflection as a Percent of Column Stacked Deflection
52
100 10079
020406080
100120
Column Stacked Stretch Tape Stretch Wrap Strapping
Load Stabilizers
Perc
ent D
efle
ctio
n
The Effect of Load Stabilizers on Load Bridging During Warehouse Rack Storage
of 55 Gallon Drums on Pallets
Average Pallet Deflection as a Percent of Unbound Drum Deflection
52
100
47
020406080
100120
Unbound Drums Stretch Wrap Vertical Strapping
Load Stabilizers
Perc
ent D
efle
ctio
n
Implications of Load Bridging Tests on Estimates of Maximum Working Loads
for pallets as described in Draft ISO TS8611-3
1. Geometry and mechanical properties of the package or container on the pallet affect the maximum working load estimate
2. The types of load binders used affect the maximum working load estimates
3. The tension applied to the load binders affects the maximum working load estimates
Implications of Load Bridging Tests on Estimates of Maximum Working Loads
for pallets as described in Draft ISO TS8611-3
4. The package or container stacking patterns affect the maximum working load estimate
5. The stiffness of the pallet affects the maximum working load estimates
6. Normal movement of the unit load changes unit load stiffness and therefore affects the maximum working load estimates