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where the denominator 8 accounts for the fact that W is a

uniform load. In some calculations for determining bend-

ing moments on beams where the applied loads are

neither strictly uniform nor strictly concentrated, it is

convenient to use the denominator 6.

Stress is directly related to the bending moment.

Mathematically,

Stress ¼

½ðin: lbÞ=in:

¼lb=in:

Figure 7. Style A, limited military-type open crate (2).

698 MARINE ENVIRONMENT AND EXPORT PACKAGING

where SM (section modulus) denotes a property of a

particular beam cross section. It is deﬁned as the moment

of inertia I (in.

) divided by the distance of the most

remote ﬁber from the neutral axis, and it is denoted by

the symbol Z or SM. A simple mathematical expression for

section modulus is (bd

)/6, where b is the width (inches)

and d is the depth (inches) of the cross section. It is clearly

observed that section modulus is extremely helpful in

determining the actual stress to which a beam is subjected

under a known bending moment.

In this section, the term ‘‘engineered’’ means that an

analysis must be made of the types of loads and their

magnitudes on the various structural members of crates

so that their required dimensions may be correctly deter-

mined by calculation.

MARKS AND NUMBERS

The purpose of marks and numbers is to identify the

shipper, consignee, and purchase order; aid in safe

handling; provide general information; and identify ha-

zardous materials. Never identify the contents unless it

happens to be hazardous materials.

Marks and numbers should be made in large (2-in.

minimum height) block letters and numbers. All numbers

such as gross and net weight and dimensions should be in

both British and metric units. Marks and numbers should

be placed on three sides of boxes and crates to ensure that

they can be seen, and these should be accompanied by

the international symbols such as the umbrella denoting

‘‘Keep dry,’’ the wind glass denoting ‘‘Fragile,’’ and the link

chain denoting ‘‘Sling here.’’ Marks and numbers should

be in permanent ink or paint that contrasts with the

background.

PRESERVATION

Some items, by their method of manufacture, are already

preserved. Others require protective coatings such as oils,

grease, paint, or some other contact preservative that may

be speciﬁed by manufacturing, engineering, quality con-

trol, or customer requirements. Some items, in addition to

contact preservatives, require a wax-paper wrapping or

some other protective ﬁlm around the item.

Certain items may require, besides contact preserva-

tives, additional protection from the elements, especially

water, such as shrouds, liners and linings, wraps, VPI or

VCI (moisture inhibitors), or desiccant materials. Wraps

applied over a contact preservative must be greaseproof

and require a means of assuring that they remain in place

during handling and transportation. Liners and linings

are waterproof-barrier materials applied between framing

and sheathing to provide watershed and diversion protec-

tion for the items crated. When shrouds are applied, all

projections in sharp corners must be cushioned to prevent

penetration or abrasion of the shroud from either internal

or external sources. The bottom edges of all shrouds

should be fastened down with batten boards and

additional restraints provided to prevent ballooning or

ﬂapping of the shrouds in transit. Adequate bottom venti-

lation must be provided either by spacing ﬂoorboards (

in. minimum) or by drilling one 1-in.-diameter hole for

each 5 ft

of shrouded volume. When VPI/VCI materials

are used, a sufﬁcient quantity of treated paper must be

used to completely enclose the item.

For general w atershed and diversion protection, polyethy-

lene ﬁlms (4 mils minimum thickness), asphalt-laminated

kraft paper, or ﬁlament-reinforced polyethylene- or polyethy-

lene-coated kraft paper may be used. When applying water-

vapor-resistant liners or lining, such as asphalt-laminated

kraft paper or polyethylene ﬁlms (6 mils minimum thick-

ness), it is essential that they be sealed tight. Whenever VPI/

VCI-treated papers are used, they must be inserted within a

tight enclosure, and the linear or lining must be sealed with

water-prooftape.Thisisalsotrueofdesiccants.

Skids, Crates, and Boxes. The materials used for skids

must be Group IV (hard) woods such as beech, birch, hard

maple, hickory, oak, rock elm, and white ash. These woods

have the greatest nail-holding power and the highest

Figure 8. Strapping for crates: (a) sheathed crate with skid

base; (b) additional strap for sill-type base (2).

MARINE ENVIRONMENT AND EXPORT PACKAGING 699

overall strength and resistance to shock. However, they

are very susceptible to splitting. These woods should be

used for skids, headers, load-bearing ﬂoorboards, and

critical joists.

Group II and III are generally acceptable for exterior

box and crate construction. Group II woods include Dou-

glas ﬁr, hemlock, Southern yellow pine, Tamarack, and

Western larch. These woods are harder soft woods. They

possess greater nail-holding power, greater strength, and

greater shock-resisting capacity than do Group I woods.

They are more inclined to split, and their grains often

deﬂect nails. Examples of Group III woods are ash (except

white), cherry, soft elm, soft maple, sweet gum, sycamore,

and tupello. These woods are similar to Group II in nail-

holding power and beam strength but have less tendency

to split and shatter under impact.

When using plywood as sheathing or ﬂoorboard mate-

rial, type C–D interior plywood with exterior glue is the

best economical selection.

Lumber Selection and Defects. A great deal of considera-

tion must be given to a standard of quality of the wood

selected for skids, crates, and boxes. Often, the cheapest

grade of lumber will contain a large number of defects that

are undesirable. Therefore, it may be necessary to select a

higher grade of lumber to eliminate most disqualifying

defects. Generally, knots are not to exceed one fourth of

the width of the member. No knot, regardless of size, will

be permitted on the edge of any member. Obviously, this

is because the member may be subjected to bending and

a knot may fall in an area subjected to compression or

tension. The cross grain or slope of grain, disregarding

slight local deviations, along the general direction of the

grain as related to the longitudinal axis of the wood

member, should not be steeper than 1 in. in 15 in. of

length. Wane is either bark or lack of wood on the edge

or corner of a piece of lumber. Generally, wane is per-

mitted on one edge only, but it should not exceed one sixth

of the width or thickness, or one third of the length of the

member. Checks and splits, which are lengthwise open-

ings from separations during seasoning, may reduce

wood’s resistance to shear. Checks and splits that extend

through the entire thickness of the piece are not per-

mitted. Shake is a separation along the grain, largely

between the growth rings, which occur while the wood is

seasoning. Shakes in members subjected to bending re-

duce the resistance to shear and, therefore, should be

closely limited in structural members. Decay, which is a

disintegration of wood, results from the action of wood-

destroying fungi. It seriously affects the strength proper-

ties of wood and its resistance to nail withdrawal. How-

ever, if it is determined that the total amount of decay

beneath the surface does not extend beyond the surface

outline, the dimensional limitations for knots apply. Warp

along the longitudinal axis of the lumber should not be

more than 1 in. in 8 in. of length. Lengthwise, warp should

not exceed

in. in 4 in. of width. The acceptable range of

moisture content in lumber used for skids, crates, and

boxes should lie between 12% and 19%.

No opportunity should be overlooked to use materials

besides wood or plywood for crate, box, or skid construction

where practically and economically feasible. Steel alter-

natives for wood skid members may be the simplest

substitution. For example, a 4-in. 4-in timber may be

replaced by a 3-in. 4.1-lb steel channel iron or by a

3in5.7-lb I-beam or by a 3-in  3-in: 

-in:-angle iron.

Wherever material substitutions are contemplated for

heavy loads, they should be engineered for the speciﬁc

purpose intended.

DESIGN

A proper analysis of forces to which skids, crates, and

boxes may be subjected must include consideration of

compression, lateral thrust, impacts, repeated handlings,

abuse, tension, and inertial forces on the structure and the

cargo. In this regard, it must be remembered that inertial

loadings encountered aboard ship often exceed those en-

countered in the other modes of transportation.

Basic Design Criteria. Skids must be of Group IV woods

and engineered for uniform or concentrated loads. Head-

ers are to be bolted using washers and double nuts or

upset threads. Skids are to be spaced not more than 48 in.

apart and are to be of single-piece construction or, if over

12 ft long, spliced according to an approved method. The

ends of skids are to be chamfered and are to rest on

chamfered rub strips. Cargo is to be bolted or tension

banded to skids using engineering design methods for

determining the sizes of bolts and tension bands. For

heavy loads, consideration must be given to the crushing

strength of the wood or alternative material. Load-bearing

ﬂoorboards can be analyzed as beams using the formulas

for bending moment to determine the required section

modulus. The allowable stress used in the formula for

section modulus can be taken as 1000 psi. For hard woods,

this allowable stress provides an adequate factor of safety.

Where the distance between skids might exceed 48 in., it

will be necessary to add an additional skid. The bending

moment on the load-bearing ﬂoorboards, then, should still

be calculated on the basis of the length between outside

skids.

For example, suppose that a 15,000-lb load is to be

supported on skids whose length has been determined

to be 15 ft. Calculate the required timber size. Using

the formula BM = (WL/6, the bending moment will be

37,500 ft lb. Then calculate the required section modu-

lus = BM allowable stress = 450 in.

Remember to multiply

the bending moment by 12 to convert foot-pounds to inch-

pounds. Because section modulus = (bd)/6, you can solve by

trial and error by substituting cross-sectional dimensions

as follows. Try a 10-in 10-in. timber. This yields a section

modulus of 166.7 in.

Two skids of these cross-sectional

dimensions yield a total of 333.4 in.

It is obvious, then,

that two 10-in. 10-in. timbers do not provide the re-

quired section modulus (450 in.

) for a quasi-uniform

load. The next logical choice would be two 12-in. 12-in.

timbers. Note, however, that if the load is truly uniform

(BM=WL/8), then the required section modulus is only

337.5 in.

The two 10-in. 10-in. timbers then come close

to making the required section modulus, and with the

700 MARINE ENVIRONMENT AND EXPORT PACKAGING

factor of safety provided by using the allowable stress of

1000 psi, the two 10-in. 10-in. timbers would serve sa-

tisfactorily for a strictly uniform load. For most hard

woods, the allowable stress of 1000 psi provides a comfor-

table factor of safety of approximately 1.5. In calculating

the basic stresses for structural lumber, impact loading is

generally ignored, but long-time loading and a safety

factor are considered. A piece of wood will carry less load

for a long time than it will for a short time. Consideration

should be given to the expected interval of storage, i.e.,

short time versus long time. In addition, if research or

historical data indicate that a particular port of loading

and/or a particular port of discharge have a higher fre-

quency of cargo claims because of rough handling, then

timber sizes may be increased by applying an appropriate

factor of safety or by requiring that the actual timber size

be one full unit larger than derived by calculation. Re-

member that rub strips must be applied to the skids. An

added precaution against the accidental loss of a rub strip

is the use of reinforcing straps from the rub strip to the

underside of the skid members.

Crates. In general, Groups II and III woods are to be

used in crate construction except for skids, headers, and

occasionally load-bearing ﬂoorboards that should be

Group IV woods. All nails used are to be cement coated.

Barbed, screw, or serrated nails are occasionally used, but

for practicality and economy, cement-coated nails make

the best selection.

All skid members in crate construction generally follow

the same construction requirements as skid members used

as skids alone. However, skid members sizes in crates can

be substantially smaller in cross-sectional area, because in

crate design, it is assumed that a large part of the load

imposed by the contents is carried by the side panels acting

as trusses. Therefore, large skids are not necessary as load-

carrying members because the sides act integrally with the

skids in this function. Although this assumption results in

smaller size skids, it does not permit handling and moving

a loaded base alone without the sides and ends fastened in

place.

Crates may be either open or closed (sheathed). It is not

always necessary to sheathe a crate if the contents do not

require a degree of protection from the elements. Opened

crates require less lumber and, therefore, if properly

designed, can be less expensive to fabricate. This may

not always be true, and to achieve greater economy, it is

necessary to make an engineering economy analysis to

determine whether an open crate or a sheathed crate is

more economical in terms of labor and cost of materials.

This article discusses the design and construction of open

crates because the contents impose loadings on structural

members that must be determined by either graphic

analysis or engineering methods of resolving forces. The

sides and ends, as well as some members of the base, are

considered as part of a bridge truss. The Howe truss, with

its parallel upper and lower chords and its vertical and

diagonal members, has the same general pattern as the

frame members of the side of a wooden crate. Because the

truss is a framed structure composed of straight members,

the stresses in the members caused by loads must be

either compression or tension. The magnitude and char-

acter of the stress in each member can be determined. The

required size of all tension members in the truss is

determined by the formula A = P/f, where A is the re-

quired cross-sectional area of the member in square

inches, P is the total load in pounds (as determined from

the resolution of forces or from graphic analysis), and f is

the working stress in pounds per square inch (in tension

parallel to the grain). With support at each end, the major

stresses in strut and lower frame members are tension

stresses, and those in the diagonals and upper-frame

members are compression stresses.

Compression members must be designed as columns,

and column formulas must be used to determine their

sizes. In crate design, essentially three column formulas

are used. The selection of the proper formula depends on

the unsupported length of the column, and columns are

therefore classiﬁed as short, intermediate, and long. It is

beyond the scope of this article to discuss the various

factors and the application of these in the appropriate

column formulas. The Wood Crate Design Manual (2) is an

excellent reference text for the more determined crate

builder. It must be remembered that it is most probable

that crates of similar dimensions will be stacked vertically

(one on top of the other) aboard ship or in storage. If crates

are of exactly the same overall dimensions, then the

corner posts will carry the superimposed loads as columns.

These anticipated superimposed loads must be included in

the strength analyses. If superimposed loads consists of

smaller crates or other types of loads that do not rest on

the corner posts, then the structural members of the top

panels will be subjected to bending as well as to compres-

sive loadings that result from handling, especially with

slings or chains. Therefore, these structural members

must be analyzed as beams subjected to bending and axial

compression.

highly

concentrated

loads (in the center

third of the crate) are to be crated, the skid depth must be

increased. This, however, will be apparent if the side

panels are properly analyzed.

Crates should not be higher than they are wide (even

well-constructed, durable shallow crates are acceptable;

see examples in Figure 9). Side panels are to be divided by

a suitable number of vertical members so that diagonals

are as close to a 451 angle as possible. Top and bottom

horizontal and vertical members are to be through mem-

bers (extend to full extent of length and height dimen-

sions). All end panels are to have one or more diagonals.

Avoid splicing members less than 16 ft long. Splicing,

where required, must be accomplished using an approved

method. Intersections of diagonals are to be reinforced

using plywood gussets or lumber bridge.

If the crate height exceeds 72 in., a through intermedi-

ate horizontal member is required at midheight of the

crate. Side-panel width (ie, between vertical members)

must not exceed 42 in. The geometry of the panels must be

altered to add an additional panel so that panel widths do

not exceed 42 in. Lower horizontal members are to rest on

the ends of the ﬂoorboards with notches cut in headers

and load-bearing ﬂoorboards to accept these lower hori-

zontal members. Vertical and diagonal members must be

in the same plane and to the outside of the horizontal

MARINE ENVIRONMENT AND EXPORT PACKAGING 701

members. Side-panel diagonals should slope from the top

of a vertical member down to the skid base.

The end-panel design should not exceed 42 in. in width.

End panels for crates with a skid width in excess of 42 in.

will require intermediate vertical members. End panels

for crates with more than two skids will require a vertical

member above each skid. Filler strips will be required to

allow end-panel vertical members to rest across the ends

of skids. The ﬁller strips will ﬁll the void between the

headers and the lower horizontal members.

Top panels are critical because most members will be in

compression under the inﬂuence of various types of

materials-handling equipment and superimposed load-

ings. Top-panel lateral and diagonal members will be in

the same plane and rest on the longitudinals and extend to

their edges.

Where protection from the elements is essential or to

meet customer requirements, a sheathed-crate, either

-in.

lumber or

-in. plywood (C–D, exterior glue) sheathing can

be used. Reinforcement strapping is required on all corners

and at all intermediate, horizontal, and vertical member

junctures after the crate is assembled.

Where crate items require additional protection from

the elements, as discussed earlier in this article, appro-

priate steps must be taken in the early stages of crate

construction to apply the required crate liner between

internal framing and external sheathing. If the crate is

not to be watertight, then sufﬁcient ventilation must be

provided. If the contents are to be provided with water-

proof protection, then the item must be properly and

totally wrapped with either asphalt-laminated kraft paper

or polyethylene ﬁlm and sealed with waterproof tape in

addition to the crate liner material.

The strength and rigidity of crates are highly depen-

dent on the fastenings. Nails, lag screws, bolts, screws,

and metal connectors are the most important fastenings

in crate construction. This article brieﬂy covers nails

and nailing rules. Refer to Anderson’s treatise on nailing

better wood boxes and crates (3) for a more complete

discussion of nails and nailing rules. Cement-coated nails

are being more widely used today than ever before,

primarily because many crate builders use automatic

nailing equipment more readily amenable to the use of

belted cement-coated nails. Nails should be driven

through the thinner member into the thicker member

where possible and should penetrate both members, leav-

ing a minimum of

in. for clinching. Clinching is one of the

best methods of increasing effectiveness of nails. It is used

almost entirely in the fabrication of crate panels, except

when frame members or other crate parts are W2-in.

thick. Clinched nails have 50 to 150% greater withdrawal

resistance than unclinched nails when driven into dry

wood. Predrilling the wood before the nails are driven may

be necessary to prevent splitting in dense woods or with

nails of large diameter. Nails should not be overdriven.

They should be positioned no less than the thickness of the

piece from the end or half the thickness of the piece from

the side edge. When members (both of which have Z3-in.

thickness) are joined together, bolts are to be used. Nails

should be staggered to prevent any two nails from enter-

ing the same grain line of any board. Follow approved

nailing techniques as outlined in the handbook described

above.

Where practical, the use of tension bands will provide

an added degree of a reinforcement to the crate assembly.

Tension bands should be tight enough to cause a light

crushing of the ends of the main structure over which they

pass. Tension bands should be stapled to prevent their

movement during transportation and handling.

Figure 9. (a,b) Typical shallow crates [(a) lumber; (b) plywood];

support was available in the top of the crate (2).

702 MARINE ENVIRONMENT AND EXPORT PACKAGING

A crate can be assembled before or after loading the

item on the skid base, whichever is appropriate, but

internal blocking and bracing of the item in the crate

must be done at the time the item is set on the skid base.

The blocking and bracing must be of substantial design

and construction to prevent the free movement of the item

within the crate caused by the forces encountered in

transportation and handling. Blocking and bracing are

not to be taken lightly. The inertial loading on the crate

and its contents aboard ship often exceeds twice that

encountered in the other modes of transportation.

Boxes. Boxes are not to be used for loads in excess of

5000 lb or lengths in excess of 16 ft. Groups II and III

woods are to be used. All nails are to be cement coated.

Boxes that exceed 200 lb gross weight will require 2-in 4-

in. rub strips. When any unsupported span of top, end, or

side lumber exceeds 36 in., additional interior battens or

cleats will be required. Cleated plywood boxes for loads

over 1000 lb must have load-bearing bases with properly

sized skids, headers, and rub strips and are to be nailed in

accordance with the preceding nailing rules. All boxes

require tension bands sized according to the load and

arranged in two directions passing over cleats or battens.

Bands should be stapled to prevent movement and

should be tight enough to cause light crushing of the

corners of the members over which they pass. If a boxed

item is of large mass (weight), appropriate ﬁller or cush-

ioning materials ﬁlling the voids around the item may not

be effective. Therefore, dunnage or blocking and bracing,

where practical, should be used. Where the boxed item

requires protection from the elements, the internal sur-

faces of the box may be lined as described under crates and

the item itself should be properly preserved.

UNITIZATION AND PALLETIZATION

Unitization provides a more economic package than in-

dividually shipped pieces. It also provides ease of handling

and storage and provides a greater degree of protection

than individual units. Pipe and conduit are easily

bundled. They may require special plastic end protectors

to protect internal or external threads. The ends of

bundled pipe can be boxed or completely covered with

double- or triple-wall ﬁberboard secured with tension

bands. In addition, long bundles may be bucked. Bucks

are wooden frames that surround the girth of the bundle.

They are to be nailed at the right angle junctures and be

tension banded. Tension bands are to be stapled to prevent

accidental loss of the bands. Bucks should be located at 5-

ft maximum intervals.

Lumber and paneling are usually bundled. Care must

be taken to avoid overtensioning bands that will mar their

edges. Paneling should be covered with water-resistant

paper or polyethylene ﬁlm.

Coiled wire can be bundled. Because of the historically

poor bundling methods used for wire, substantial losses

have occurred. Consignees frequently use coiled wire to

make nails, screws, and bolts. Kinked or crooked wire will

interfere with the extrusion process, and substantial

claims may arise.

Lumber and paneling can also be bundled. Care must

be taken to ensure that tension bands do not damage the

items bundled. Coiled wire can be bundled. The usual

problem encountered here is when tension bands or

wrapping wires comes off, allowing the coils to become

disarranged or crushed. The consignee usually has a

speciﬁc machine set up for manufacturing items such as

bolts, screws, and rods. Hence, damage to the coils can

result in a claim.

Palletization is best for similar-size ﬁberboard cartons,

drums, and coiled sheet steel. Do not overload or stack the

items too high. Overloaded pallets break. An excessively

high stow can result in crushing of the cartons in the lower

levels. Then, more damage occurs when the otherwise

neat stacking falls apart. In-transit handling of broken-

down pallets usually results in additional abuse. Fabric or

steel banding is usually one of the best methods of secur-

ing an entire unit load. It may be advisable to employ

vertical and horizontal corner protectors to eliminate

banding damage. Shrink wrapping provides a high-

strength securement to a palletized load. It can also be

applied to protect against contact with water.

Palletized drums must be ﬁtted with partially framed

tops to allow for safe use of tension bands. Tensioning of

the bands must not cause damage to the pallet load-

bearing boards or to the cargo. Fiberboard sheets across

the top and partially down the sides of drums will serve to

keep the tension bands positioned and provide a level

surface for stacking other pallets.

In general, old or badly worn pallets should not be used.

Pallets can be repaired. Some companies use secondary

reusable pallets with good success. Still, old wood and

loose nails can result in broken pallets that invite further

abuse in handling.

CONTAINER PROBLEMS

Containers are subject to the same shock and vibration

forces as are over-the-road trailers and railroad cars. In

addition, high inertial loadings are experienced by the

contents as a result of swaying, pitching, rolling, heaving,

yawing, and surging of a ship at sea.

The major causes of damage to containerized cargoes

are improper stowage, inadequate dunnage, lack of secur-

ity, overloading, and poor weight distribution. Any as-

sumption that the container is a substitute for safe

stowage and handling is an invitation to disaster. A good

rule to adopt is to stow and secure for the worst conditions.

Containers may travel to seaport by railroad. Constant

vib

ration and

occasional sharp humping forces must be

taken into consideration. When loading a container for sea

transport, always consider the six basic ship motions: yaw,

heave, sway, pitch, roll, and surge. Occasionally heavy seas

will have a pronounced effect on cargoes in containers.

Blocking and bracing is essential to the safety of the

cargo. Materials commonly used for securement are lum-

ber, plywood, strapping, ﬁberboard, and inﬂatables. Lum-

ber can be used as a ﬁller for decking, blocking and

bracing, and constructing partitions. Plywood can be

used as a partition, divider, and auxiliary decking.

MARINE ENVIRONMENT AND EXPORT PACKAGING 703

Heavy-duty strapping can be used to separate cargo and to

tie down heavy and awkward items. The strapping must

be ﬁrmly anchored and properly tensioned for the greatest

effectiveness. Fiberboard is available in sheets, rolls, and

structural shapes and can be used for light-duty bracing,

as dividers, decks, and partitions. Inﬂatables are available

in paper or rubber and may be reusable or disposable.

They are expensive and not recommended for voids in

excess of 18 in. Inﬂatables are used for light- and medium-

duty bracing.

Condensation is another major cause of damage to cargo.

It is not generally known that ﬁberboard boxes and crate or

dunnage lumber contribute to the generation of water vapor

in sea containers. Furthermore, in changing temperature

and humidity conditions, condensation can form within

containers and drip down from the overhead onto moist-

ure-sensitive packaging and cargoes. These conditions can

be remedied, in part, by using seasoned lumber for dunnage

and crate construction. Adequate (prepackaging) preserva-

tion of moisture-sensitive items can be the best method of

protecting against water damage. Overwraps such as canvas

or polyethylene sheeting will serve to divert condensation

that drips from the overhead. W ith some types of cargoes, it

may be necessary to provide completely waterproof liners or

wraps constructed VCI/VPI or desiccant materials. Cargoes

are more likely to be subjected to condensation and water

damage over a long time interval such as long transportatio n

distances or long-duration storage. Therefore, it is incum-

bent on the shipper to consider all these factors when

preparing cargo for export.

The annual report of the Cargo Loss Prevention Com-

mittee of American Institute of Marine Underwriters

contained valuable advice on the use of containers in

shipping. Extracts from the report follow:

Normal reaction is for a shipper to use domestic packaging and

consider the container as an additional protection. It is our

experience that containers may leak and the cargo must be

protected against moisture and water damage. Additional

emphasis is needed on the use of dunnage and tight packing

in containers.

Several ofﬁces report that losses have been experienced due to

defective containers. Many shippers do not employ adequate

container inspection procedures. It appears that some insur-

eds think that because their goods are containerized the

packing can be of a minimal nature. Our experience continues

to show that such minimally packed goods are likely to be

damaged by rain and/or seawater when shipped in poorly

maintained containers.

Many shippers continue to use containers as a means of

packaging and claims due to crushing, water damage and

improper or inadequate stowage, especially of heavy machin-

ery, continue to be a problem.

Losses have also been experienced where shipments of high

value electronic units have been made in containers. The

units are sec ured on lumber bases which in turn are then

secured to pallets with the units being entirely shrouded in

polyethylene sheeting which also encompasse s the wooden

base to which the units are attached. It was found that these

wooden bases were constructed of green or improperly dried

lumber, which ga ve off moisture, which became trapped in the

polyethylene shrouding. During the course of transportation,

ﬂuctuati ons in temperature caused this moisture to condense

on the exposed metal areas of the electronic unit, causing

serious damage.

We have also observed that machinery which is top heavy has

on occasion been stowed in containers without adequate

bracing and precautions to prevent the machine from tipping.

On one occasion, a container loaded with tractor engines

arrived at destination with every engine damaged, as a result

of their center of gravity being high. Although the engines

were braced along the ﬂoor of the container, and would

prevent lateral or fore and aft movement, there was no bracing

up higher and with their relatively high center of gravity they

tipped, coming in contact with one another, causing damage.

Shippers should be cautioned to be aware of the center of

gravity of machinery and other heavy or odd sized pieces being

shipped in containers and adequate bracing to prevent tipping

should be done.

Although containerization of cargo continues to grow world-

wide, the packing of goods into house to house containers by

shippers, as well as securing of the goods in the containers,

continues to be a cause for concern. We ﬁnd in many instances

cargo to be damaged by condensation within the container

and/or by extreme heating or freezing. Once a container is

loaded and the doors securely shut, the only way in which the

outside weather can affect the cargo is through changes in the

temperature.

Unless the internal temperature of the container is controlled

by mechanical or other means, the temperature of the air

inside the container will follow the temperature of the air

outside. Extreme ﬂuctuations in the air temperature can cause

condensation to settle on the cargo; if the container is exposed

to very high temperatures, the cargo within the container may

sustain damage or, if the container is exposed to extremely low

temperatures, the cargo can be damaged, such as change in

the chemical state of some goods (eg, drugs) making them

useless and sometimes dangerous, or freezing of bottled

liquids with subsequent bursting of bottles.

Taking into account the anticipated voyage, its length, and

temperatures normally expected to be encountered, considera-

tion should be given to goods which are susceptible to damage

by extreme heat or cold by shipping them in insulated or

refrigerated containers where the temperature inside the

container can be controlled to some degree.

In other cases, certain precision machinery or electronic

equipment may require the use of VCI, VPI or powder

desiccants. It must be pointed out, however, that in order for

these moisture control measures to take full effect, the packa-

ging and packing must be totally sealed.

SHIPPING LOSSES AND INSURANCE

Under normal conditions of domestic rail shipments,

material loaded in open cars is inspected by railroad

representatives before the car is moved, and the railroad

assumes responsibility. In closed cars, however, the Asso-

ciation of American Railroads rules are not mandatory

and are used only for guidance. Closed cars are not

ordinarily inspected, but if damage occurs to the contents,

they are inspected at the destination to determine the

cause before a settlement is made.

Export shipping companies are speciﬁcally exempt

from most forms of liabilities under the laws of many

countries. The exceptions to this usually include loss or

damage due to negligence in proper loading, custody, or

delivery of the goods.

704 MARINE ENVIRONMENT AND EXPORT PACKAGING

The shipper or consignee must assume responsibility

for all remaining risks during the shipment.

To prevent loss to the shipper, a form of marine

insurance covers these losses. Marine insurance may be

obtained to cover such perils as pilferage, theft, and

leakage, as well as loss or damage if the ship should

sink, burn, or be involved in a collision. However, the

more hazards covered by the policy, the higher the rate, so

it is not economical to pay for broader protection than is

actually required.

Rates in marine insurance are rather complex and are

not ﬁxed. They depend on, among other things, the type of

vessel, the route, the perils insured against, the type of

packing used, and the loss record of the shipper. This

latter factor reﬂects the type of container and the method

of cushioning, blocking, and bracing used by the shipper,

because well-constructed and well-packed crates will nor-

mally receive little damage during the voyage. A shipper

who uses adequate containers pays lower rates. Under-

writers keep statistical records of shippers with whom

they deal and allow lower rates for those with good

records.

DAMAGE AND CLAIMS

Too frequently one or more of the three steps in prepara-

tion for shipment are less than adequate, and this will

inevitably result in damage of one type or another to the

cargo. Precision machinery shipped long distances or

subjected to long-term storage without adequate preser-

vation will rust. Electronic equipment shipped without

serious consideration being given to adequate protection

from vibration and shock will sustain physical damage.

Items requiring a degree of dimensional stability (rigidity)

will be damaged if the packaging and packing is not

properly engineered and constructed. One way to ensure

greater construction durability is by preshipment damage

testing of crates or other containers (see Figure 10).

With regard to containerization (sea containers), a

tremendous number of cargo losses occur each year be-

cause of ignorance of the proper use of these containers,

speciﬁcally the requirement for adequate blocking and

bracing and protection of the cargo against condensation.

It is imperative that the shipper understand that the use

of sea containers does not guarantee that the cargo will be

received by the consignee in sound condition.

A major marine insurance company has made an

analysis of principal causes of losses and found that, in

the ‘‘handling and stowage’’ category, 39% of all losses are

caused by container damage including breakage, leakage,

and crushing. In the ‘‘water damage’’ category, 10% of all

losses are from fresh-water, sweat, and saltwater damage.

Nevertheless, it concludes that 70% of all cargo losses are

preventable.

CONCLUSION

In summary, shippers would do well to have as their ﬁrst

concern ensuring that the goods reach their customers in

sound condition, and to that end, the author hopes that

this article is a valuable aid.

BIBLIOGRAPHY

1. U.S. Department of Agriculture, Wood Handbook, Agricultural

Handbook No. 72, Forest Products Laboratory, Madison, WI,

1974.

2. U.S. Department of Agriculture, Wood Crate Design Manual.

Agricultural Handbook No. 252, Forest Products Laboratory,

Madison, WI, 1964.

3. L. O. Anderson, Nailing Better Wood Boxes and Crates, Agri-

cultural Handbook No. 160, USDA, 1959.

Figure 10. Rough-handling tests for crates; (a) superimposed

load; ( b) edgewise drop; (c) cornerwise drop; (d) pendulum impact

(2).

MARINE ENVIRONMENT AND EXPORT PACKAGING 705

General References

Code of Federal Regulations,49CFR Parts 100–199, Subparts D

and E, Ofﬁce of the Federal Register, National Archives and

Record Service, Oct. 1978.

J. P. Colletti, Export Packing in the Marine Environment, U.S.

Department of Commerce, Damage Prevention in the Trans-

portation Environment, Mechanical Failures Prevention

Group, National Bureau of Standards, Gaithersburg, MD,

Oct. 1981, pp. 8–37.

Departments of the Army, Navy, and Air Force, Packaging of

Materiel: Preservation, Vol. 1, Manual DSAM 4145. 2, 1976.

W. Friedman and J. Kipnees, Distribution Packaging, Krieger,

New York, 1977.

J. F. Hanlon, Handbook of Package Engineering, McGraw-Hill,

New York, 1971.

U.S. Department of Transportation, A Shipper’s Guide to Stowage

of Cargo in Marine Containers, Maritime Administration,

Washington, DC, 1982.

MATERIALS HANDLING

STEPHEN A. RAPER

The University of

Missouri-Rolla, Rolla, Missouri

COLIN BENJAMIN

Florida A&M University,

Tallahassee, Florida

INTRODUCTION

The Industrial Revolution of the late 18th–early 19th

century saw the introduction of powered machines to

replace manual labor in accomplishing the same or similar

tasks. Consequently, gains in labor and productivity per

worker-hour of individual workers were accomplished.

Moreover, this time period observed the transition from

a ‘‘domestic system’’ to a ‘‘factory system.’’ Concurrently,

the need for materials-handling systems (MHSs) in-

creased to meet the needs of the more ‘‘productive’’ factory

system. Initially, this need was for labor-saving devices to

handle material in manufacturing and distribution (1, 2).

However, in today’s competitive and global marketplace,

the rationale for materials-handling systems is

multifaceted.

The ‘‘cost’’ estimates for materials handling vary in

nature. Generally materials handling does not add value

to the product, but it can and does add to the ﬁnal product

costs. Estimates of this cost range from as little as 20% up

to 90% in some cases. Conversely, however, efﬁciently

designed materials-handling systems have been known

to reduce a plant’s operating cost by 15–30% (3). This

ﬁgure could vary depending on the industry and product

categories. For example, the food-processing industry

would have a fairly high per-unit cost, whereas an in-

dustry that uses tanks and pipes would have a signiﬁ-

cantly lower per-unit cost.

The potential costs and beneﬁts associated with mate-

rials-handling systems are signiﬁcant and thus impact our

domestic and global competitiveness. This article provides

an overview of materials-handling principles and guide-

lines, and it relates these to the ﬁeld of packaging.

Generalized deﬁnitions, objectives, principles, and exam-

ples of materials-handling checklists are included. Brief

discussions on equipment are also presented, as well as

approaches toward the design of materials-handling sys-

tems. Because of the strong relationship between facilities

layout and materials handling, a brief section on techni-

ques for facilities layout is also included. A ﬁnal section

showing the relationship between packaging and materi-

als handling concludes the article.

DEFINITIONS

Simplistically and intuitively, materials handling is de-

ﬁned as handling material. However, various authors

deﬁne this term in increasingly comprehensive manners.

Meyers (4) indicates that materials handling is ‘‘the func-

tion of moving the right material to the right place, at the

right time, in the right amount, in sequence, and in the

right position or condition to minimize production costs.’’

He also states that materials handling involves the hand-

ling equipment, the storage facilities, and the control

apparatus. Tompkins and White (5) similarly state that

materials handling uses the right method to provide the

right amount of the right material at the right place, at

the right time, in the right sequence, in the right position,

in the right condition, and at the right cost. Again, the

emphasis is more than just handling materials. Storage

and control are also important. Time utility—the right

material at the right time—and place utility—the right

material at the proper place—are also emphasized. They

also point out that materials handling can be described in

terms of quantity, position or orientation, condition, space,

proﬁt, quality, safety, and productivity, which are also

signiﬁcant factors relative to packaging.

Gelders and Pintelon (2) offer the following deﬁnition

from an engineering point of view: ‘‘the art and science

involved in picking the right system, composed of a series of

related equipment elements or devices designed to work in

concert or sequence in the movement, packaging, storage

and control of material in a process or logistics activity.’’

Sims (6) states that materials handling includes the move-

ment of liquids, bulk solids, pieces, packages, unit loads,

bulk containers, vehicles, and vessels. He also deﬁnes a

materials-handling system as a series of related equipment

elements or devices designed to work in concert or sequence

in the movement, storage, and control of material in a

process or logistics activity, where each system must be

custom designed for each unique application. Finally, Sims

(6) states that materials handling is the portion of the

business and economic system that affects the physical

relationship of material, products, and packaging to the

product, process, facility, geography, or customer without

adding usable worth or changing the nature of the products.

Clearly, materials handling is more than ‘‘handling

materials.’’ It is a complex, multifaceted activity that ex-

tends beyond the physical conﬁnes of a manufacturing

facility. Properly designed materials-handling systems ,

706 MATERIALS HANDLING

although not adding value to a product, have the potential

to minimize overall costs, a nd even in the case of product/

package-delivery systems, impact the end-use customer or

consumer.

OBJECTIVES OF MATERIALS HANDLING

It is generally accepted that the primary goal of material

handling is to have the least possible handling, i.e., less

handling at less cost leading to reduced costs of produc-

tion. However, a more speciﬁc and comprehensive set of

objectives that more accurately reﬂects the diverse nature

of materials handling, as stated by Gelders and Pintelon

(2), are as follows:

. To increase the efﬁciency and effectiveness of mate-

rials ﬂow

. To increase productivity in manufacturing (plant) or

in distribution (warehouse)

. To increase space and equipment use

. To improve safety and working conditions

. To reduce materials-handling costs

. To avoid high capital requirements

. To ensure a high level of systems ﬂexibility, relia-

bility, availability, and maintainability

. To improve integration between materials and infor-

mation ﬂow

. To smooth the ﬂow of materials through the logistics

pipeline (from supplier to ﬁnal customer)

How can these objectives be achieved via appropriate

materials-handling system design? The following section

provides guidance on basic principles, checklists, and

critical questions that may be used to meet one or more

of the above objectives.

BASIC PRINCIPLES OF MATERIALS HANDLING

To meet the primary goal of materials handling, as well as

the expanded objectives listed above, a list of principles

based on accumulated knowledge and practice of experts

in the ﬁeld has been developed. The list of 20 principles

adopted by the Materials Handling Institute Inc. provides

rule-of-thumb advice that facilitates optimized materials-

handling system design and also serves to help develop

checklists relevant to the system under focus. A slightly

modiﬁed version (2) is shown in Table 1. These 20 princi-

ples provide an initial frame of reference to begin

the design of a new materials-handling system, make

modiﬁcations to an existing system, or analyze a system

to determine whether it is meeting predetermined

objectives.

METHODS OF ANALYSIS

Analysis of existing or proposed materials-handling sys-

tems can be approached in either a qualitative or quanti-

tative manner. To facilitate the analysis of a materials-

handling system in general, Tompkins and White (5)

Table 1. Basic Principles of Materials Handling

1. Planning: Study the problem thoroughly to identify potential solutions and constraints and to establish clear objectives.

2. Flow: Integrate data ﬂow with physical materials ﬂow in handling and storage.

3. Simpliﬁcation: Try to simplify materials handling by eliminating, reducing, or combining unnecessary movements and equipment.

4. Gravity: Use gravity to move materials wherever possible, while respecting limitations concerning safety and damage.

5. Standardization: Standardize handling methods and equipment wherever possible.

6. Flexibility: Use methods and equipment that can perform a variety of tasks.

7. Unit load: Handle products in as large a unit load as possible.

8. Maintenance: Plan maintenance carefully to ensure high system reliability and availability.

9. Obsolescence: Make a long-range plan, taking into account equipment life-cycle costs and equipment replacement.

10. Performance: Determine the efﬁciency, effectiveness, and cost of the materials-handling alternatives.

11. Safety: Provide safe materials-handling equipment and methods.

12. Ecology: Use equipment and procedures that have no negative impact on the environment.

13. Ergonomics: Take human capabilities and limitations into account while designing a materials-handling system.

14. Computerization: Consider computerization wherever viable for improved materials and information control.

15. Utilization: Try to obtain a good use of the installed capacity.

16. Automation: Consider automation of the handling process to increase efﬁciency and economy.

17. Operation: Include operating costs (energy) in the comparison of materials-handling alternatives.

18. Integration: Integrate as much as handling and storage activities into one coordinated system, covering receiving, inspection, storage,

transportation, production, packaging, warehousing, and shipping.

19. Layout: Keep in mind that layout and materials handling are closely linked and that an interactive procedure is often needed to obtain

their best coordination.

20. Space use: Choose the material handling equipment so that effective use is made of all (cubic) space.

Source: Reprinted with permission from Materials Handling Institute, Inc.

MATERIALS HANDLING 707