June 2005

Proper Packaging Required to Maintain Traceability

By Val Miller

How many times have you purchased a new piece of equipment, whether for personal or
business use, and received it packaged so that you felt like you were unwrapping Fort
Knox. Layer after layer of packaging must be removed, and then you find the paper in
the container recommending that you Retain the original packaging for possible future
shipment." In all probability, you did not follow that recommendation, whether because
of storage space or a lack of understanding of the importance of proper packaging.

Recently, an alarming number of standard artifacts being shipped between laboratories

have been damaged because of failure of the packaging to protect the contents. Poor
packaging has caused significant damage to the artifacts resulting in loss of data and, in
some cases, complete loss of the artifacts. NIST Handbook 44, Appendix A, section 3.3,
Accuracy of Standards, discusses the need for having calibrated standards. The second
paragraph of this section states: "Accurate and dependable results cannot be obtained
with faulty or inadequate standards." Poor packaging can result in faulty standards.

Besides having the standards calibrated for each use, how is this accomplished? Since
the majority of the standards used in legal metrology are made of metal, it is so easy to be
lax in our care of them. We think, "It's steel; it doesn't need any special care." But keep
in mind that though they are made of steel or some other metal, the material is not the
property of the device that we utilize in our tests. Instead, it is the shape and size
(volume), the total amount of material (mass) or distance between two marks (length),
which are of concern. When a weight slides across a truck floor or scale deck, small
amounts of material are removed by friction. Since the known amount of material is the
property used in the test, we now have lost, or should have lost, confidence in the
accuracy of the value.

Steel test measures have been observed being transported in the back of a vehicle without
being restrained or protected. The property of the test measure that we use is the shape
and volume. If the test measure contacts another object and is deformed from the shape it
had when last calibrated, its accuracy is lost. Even dents that are not visible to the eye
can cause errors in volume that far exceed the allowable one-third of the applicable
tolerance. In both situations the standards are now faulty and inadequate for use in
testing.

Laboratory standards are many times shipped to another laboratory for calibration. The
value in the calibration is the reported measured result and uncertainty. If damage occurs
during shipment, there can no longer be confidence in the reported measurement result,
and any funds expended for the calibration are wasted.

Major shipping companies such as Federal Express and United Parcel Service have made
packaging recommendations and shipping guidelines available both in paper form and via
their Internet sites. They recommend that the original packaging be maintained and re-
used, and that additional layers of packaging may be required to adequately protect the
item being shipped.

Some of their other recommendations may seem extreme, i.e., always using a new box
for the outer layer of packaging, using at least two inches of plastic bubble packaging or
foam material around each inner box or container (four inches for fragile items), ensuring
that all edges and sharp corners are taped or rounded, using at least three strips of tape for
top and bottom of a carton and using three or even more layers of packaging materials for
fragile items. These recommendations may seem excessive, but they help ensure that the
item reaches its destination safely.

For legal metrology standards this is very important, whether we are transporting them
from one test location to another or shipping them across the country for calibration. It is
important even for those large cast iron weights used to check large capacity scales. Any
damage, even if not visible to the eye, can change a standard's property of interest. The
Fundamental Considerations require that the error in the standard be less than one-third
of the tolerance being tested. The only way to ensure that our properly adjusted and
calibrated standards continue to meet this requirement is to ensure that proper packaging
is used, whether shipping across the country or just being transported across town.

To apply the guidance provided by these experts to precision mass standards, follow
these five basic steps:
1. Wrap the item in a fine lint-free paper (do NOT use plastic materials in direct contact
with the item's surface);
2. Next, cover the item with several layers of clean. lint-free cheesecloth;
3. Seal the item in a plastic bag, if appropriate;
4. Wrap the entire package in several layers of plastic bubble packaging material; and
finally,
5. Place the wrapped mass standard in a container made of material suitable for
protecting the standard.

Exterior packaging materials will vary with the mass of the standard. Heavier items will
require more durable materials be used. Multiple layers of packing containers are
recommended.

Even when the manufacturer's case is available for the mass standards, you should still
wrap the weights in fine lint-free paper before inserting them into the case. This protects
the weights from contamination that may be in the case and from damage caused by
abrasion if the weights move during transit. Very small weights, such as milligram
weights, should be individually wrapped in a small piece of fine lint-free paper before
placing them in their designated spot in the case. The extra material provides padding to
keep the weights from being damaged or folded during transport. And finally, ensure that
sufficient material is placed on top of the leaf weight cover so that it is firmly held in
place and does not move during transit, but not to the extent that the leaf weights are
damaged. Excessive leaf weight covers in small weight kits have caused a number of
small mass standards to be damaged beyond use by causing the weights to be folded so
that they break when being straightened out. Weights in manufacturer's cases must be
restrained from all movement or damage is likely.

Routine transport of mass field standards may not require protection to the degree
provided by the items in the list above, but they should still be protected from damage by
restraining them within the transport vehicle and keeping them covered to prevent debris,
such as mud, dust and water, from accumulating on the surface.

Volume standards must be protected in a manner suitable for the size of the standard and
the material from which they are made.

Small metal volume standards should be:

1. Packaged in a metal container provided by the manufacturer, or placed in a snuggly
fitting double- or triple-walled cardboard box, if the original container is unavailable,
ensuring that the standard is restrained from movement within the container; and
2. Placed the container inside a double- or triple-walled cardboard container, or one made
of metal or wood, for added protection.

Large truck- or trailer-mounted volumetric standards must also be protected from

damage. Though quite large and made of metal, the size and shape of these standards
must be protected. Protection methods for these items can cover a range of possibilities
too voluminous for this article and may include procedural, as well as physical, methods.
However, sight gauges, levels, and level mounts, which are critical to obtaining good
measurement results, must always be protected from damage.

Glassware should be packaged as follows:

1. Wrap in multiple layers of plastic bubble packaging material;
2. Place inside a cardboard box or tube that fits snuggly around the wrapping material;
3. Place this box in a much larger box (at least six inches larger on each side) that is
filled with energy-absorbing materials to a level that will position the smaller box at the
center. The larger box is then filled with more energy-absorbing materials so that the
smaller box is fully restrained from movement when the outer box is taped closed.
4. As recommended in a Federal Express brochure for fragile items, use a third layer of
box and energy-absorbing materials.

Liquid-in-glass thermometers are another type of standard that is difficult to safely

package. Experience shows they should be packaged in a manner similar to glassware,
though additional stiffening provided by a piece of wood or a case stiffened with wood
should be used.
1. Place the thermometer in the manufacturer's case;
2. Attach the case to a piece of wood having a minimum thickness of 0.25 inch using
tape or elastic bands;
3. Place this assembly in a sturdy plastic bag (this will capture the contents if breakage
occurs);
4. Wrap the plastic bag-encased item in multiple layers of energy-absorbing materials;
5. Place this box in a much larger box (at least six inches larger on each side) that is
filled with energy-absorbing materials to a level that will position the smaller box at the
center. The larger box is then filled with more energy-absorbing materials so that the
smaller box is fully restrained from movement when the outer box is taped closed;
6. Use a third layer of box and energy-absorbing materials (recommended).

Length standards should be packaged in a manner determined by the design of the

standard. Steel tape measures that have a case can be wrapped in energy-absorbing
materials and transported in a single layer box.

Tape measures on an open reel should follow these guidelines:

1. Wrap item in protective film;
2. Next, wrap several layers of energy-absorbing materials around item;
3. Place in a box that snuggly fits the wrapped item;
4. Place the box in a larger box filled with energy-absorbing materials so the inner box is
approximately centered in the outer box.

Steel rulers, on the other hand, should be:

1. Wrapped in protective film;
2. Taped to a stiff piece of wood or other rigid material to prevent bending; and
3. Placed in a large box or mailing tube that provides adequate protection.

To ensure that the artifact arrives safely, one additional precaution should be taken. If
shipping the artifact in a wooden crate or box, be sure that the sides, bottom and lid of the
container are secured using a suitable banding material. Banding should be added
whether or not the box is an inner layer of protection or the outermost layer. The addition
of banding material serves to strengthen the container by restricting movement of the
container walls and also prevent damage to the artifact by making it difficult for
unauthorized personnel to open the container.

If a hardened container such as those manufactured by a number of companies, i.e.,

Anvil, is used, banding may not be required, but a tamper resistant seal or locking
mechanism is strongly recommended to restrict access. Ensure that items or boxes inside
the hardened container are held rigidly in place or damage to the artifact is likely.

Shipping artifacts so that the traceability of the associated calibration value is not lost
because of damage to the artifact is possible. It just requires proper planning and
packaging. And, when possible, use the recommendations of the packaging and shipping
experts.