Pallet Standards Gain Importance

They are standards-setting organizations. Each is different, and each has its own set of testing methods upon which the standards they set are determined.

Standards are not necessarily something that pallet customers ask about, although they may be better off if they did instead of blindly ordering a GMA or a shingle pallet. Pallet manufacturers may benefit, too; when they price a pallet designed and built to meet the same standards, the playing field among competitors tends to level off, eliminating tactics such as reducing deck board thickness in order to shave costs.

Manufacturers of plastic pallets often cite pallet performance results in their marketing literature, but questions have been raised about the choice of certain tests that may result in misleading information about their products.

In developing packaging standards, the American Society for Testing and Materials (ASTM) strives for a consensus among packaging and pallet manufacturers and users. The approach was clearly evident during a recent four-day ASTM packaging committee meeting in Seattle; there was a good balance between manufacturers and users.

A well-written standard uses technology and tests that simulate actual conditions, are enhanced by quality control programs, and are perfected by reason and practical experience, according to ASTM president James Thomas. Success or failure of a standard could rest on the slightest nuance, the minutest detail, on one question asked or not asked, he noted in a recent column written for Standardization News, an ASTM publication. “That one question can make all the difference if everybody is present,” he wrote.

The process of evaluating and modifying standards can be a very slow one, and the pace was evident at some of the ASTM meeting sessions. ASTM has taken steps to speed up the process recently, but James noted that forging a consensus among different parties can be time-consuming.

Some of the sessions were more informal than meetings or seminars sponsored by trade organizations; they were led by volunteers instead of staff. The chairman of one panel could not attend because his company would not pay his way. At some sessions it was not clear who was leading, and some gatherings seemed to lack a clear agenda.

In spite of the slow pace and informal structure, ASTM seems very highly regarded by packaging and pallet researchers and professionals. “ASTM has the most rigid standards of anyone in the world,” said Al McKinlay, a veteran corrugated packaging consultant who works closely with ASTM and other standards organizations. He chaired a packaging design session during the ASTM meeting.

Standards are developed by ASTM and the American Society of Mechanical Engineers (ASME). Another organization, the American National Standards Institute (ANSI), is the sole representative of the U.S. at proceedings of the International Standards Organization (ISO). “If anyone wants to present an issue to ISO, they have to work through ANSI,” explained Al. “It’s like a funnel.” Each country gets one vote at ISO meetings.

Dr. Jim Reeves, a consultant with the Canadian Pallet Council, noted that standards for transport packaging — including pallets — are an important consideration in international trade.

Dr. Marshall (Mark) White, director of the Virginia Tech pallet and container laboratory, is chairman of the U.S. ISO delegation and several ASME and ASTM pallet standards committees. “I believe that standards are important, so I continue to be involved in them as part of the pallet lab’s operations,” he said.

Mark is responsible for nine ASME pallet standards. “We drafted a new standard for pallets in automated material handling systems which is just now being balloted by ASME committee members,” he said.

Mark and Dr. Paul Singh of Michigan State University’s school of packaging were co-chairs of an ASTM committee assigned to revise pallet standards that were developed in the 1980s; the revisions, made to allow for testing of pallets made of alternative materials such as plastic, were issued in 1994. The panel since has revised the standards again to include performance criteria and conditioning; the latest changes are expected to be issued soon.

The move to set standards for pallets made of materials other than wood began in the 1980s when the plastic products group of the Material Handling Industry of America approached ASTM about developing standard testing practices for plastic pallets. At the time, ASTM pallet standards did not apply to plastic materials.

ASTM turned to Mark because the pallet lab had taken the lead in drafting standards that had been issued in 1985; the group asked him to help develop a new test or to revise the standard. He partnered with Paul, and they co-chaired the ASTM task group, which included representatives of wood, plastic, and corrugated pallet manufacturing interests.

The group met initially to discuss how to approach the issue. “We had to decide if there would be one standard or more than one standard testing practice — one for wood, one for paper, and one for plastic, for instance,” Mark said. Group members agreed on the need to establish a single standard. Mark and Paul led the task group through the process of revising the 1985 standard so that it could be used to test pallets made of any material. The new standard was issued in 1994.

The new standard was different in a few important respects: conditioning schedules and load application methods.

Some materials are affected by changes in temperature, relative humidity and environmental moisture conditions. For this reason, conditioning of pallets was required prior to testing, depending on the material. Plastic pallets, for example, were required to be conditioned both to 60 degrees and minus-25 degrees Celsius prior to testing.

Load application methods also were modified. “The load applicators in the previous version were really only applicable to stiff, strong wood pallets,” Mark explained. The original load applicators were two rigid bars that did not simulate a uniformly distributed load. “Once you got into less stiff pallets, it didn’t give very realistic measurements,” said Mark. “So we changed the procedures so there were all sorts of options on the load applicators you could use.”

After publication of the revised standard in 1994, Mark looked ahead. “I said to the task group that the next thing we should publish are performance criteria.” The 1994 version addressed testing methods but not testing outcomes — what results were acceptable and what were not.

The latest version, still under development, contains only slight changes to testing methods but adds pallet performance criteria. In the new version, however, performance criteria were established only for wood pallets. “We have a lot of experience on wood pallets and these criteria work well on them,” Mark said. “Nobody had enough experience yet with plastic pallets to say what were comparable performances. You have to remember that these types of tests for plastic pallets are fairly new.” The performance criteria in the new revision relate to deflection limits and strength. Deflection limits generally are applied as a percentage of span.

With another revised standard approaching completion, however, the Reusable Plastic Container and Pallet Association (RPCPA) recently announced that it would issue its own engineering guidelines for plastic pallets and containers. John Healy, president of the National Wood Pallet and Container Association, suggested the RPCPA may be trying to duck head-to-head comparisons of plastic and wood pallets and containers. Mike Ogle, staff liaison at Material Handling Industry of America, disagreed. “Many of the RPCPA guidelines focus on (plastic) bulk boxes and totes rather than pallets,” said Mike; the new standards being considered by ASTM address only pallets, he noted.

Jim Favaron, chairman of the RPCPA engineering committee, has indicated that the RPCPA wants to develop uniform testing methods to enable potential customers to evaluate different plastic pallet and container products and suppliers. In addition, RPCPA and ASTM testing methods are very similar, he suggested. “ASTM has been looking at plastic product testing, as well as AIAG, the automotive industry action group, and ISO a little bit,” he said.

The new RPCPA guidelines and the new ASTM pallet standard now under development are very similar, according to Mark. Since it is being expanded to include materials other than wood, the standard necessarily will become more complex. For this reason, he suggested, plastic pallet interests may desire a simpler format.

Researchers indicated there was little evidence of bias in test selection by pallet manufacturers in order to achieve misleading performance results and to gain a competitive advantage. However, they warned that problems can arise if claims of pallet performance found in sales literature are not adequately clarified or explained.

For example, Paul pointed out that a performance rating may not specify what type of load upon which the rating was based. A brochure may indicate a certain performance level for a pallet without acknowledging that it is based on a uniformly distributed load. For a company considering buying the pallet to use with an unstable bulk load, such a claim would be misleading; their application would reduce the safe load limit of the pallet.

A common complaint over the years among the wooden pallet industry has been the claim that plastic pallets are rackable. “Every pallet is rackable,” Mark observed. “It’s just a question of what load geometries and what load masses it can safely rack, at what span.” Pallet users may be misled, he said, not by a manufacturer’s claims about pallet performance but by a lack of understanding of the testing methods upon which the claim is based. “That’s the real issue,” he said.

Similar confusion exists over claims of how many trips a pallet may be expected to last. Henry Brown, a veteran designer for plastic pallet maker TriEnda, noted that researchers and vendors may differ over what constitutes a pallet ‘trip’ — how many times the pallet is handled and transported for a single ‘trip.’ As a result, marketing claims about how many trips may be expected from a pallet may not be particularly useful for comparisons.

In the packaging arena, Al said, misleading claims are rare. “I hear about it once in awhile, but in packaging it’s not prevalent.”

How many pallet manufacturers actually use published standards? The standards are used by researchers who do the testing, according to Mark. “Hopefully,” he said, “information comes out of these tests that are then useful to the pallet maker.”

Pallet makers should be familiar with ASME standards for wood pallets, he suggested. With few exceptions, they are the same as the NWPCA uniform standard for wood pallets. These guidelines delineate minimum quality requirements for wood parts, fasteners, and pallet assembly.

The Pallet Design System computer software, developed by the Virginia Tech pallet lab and the NWPCA, is based on the NWPCA uniform standard. “So PDS de facto is a standard design procedure,” said Mark.

Pallet manufacturers probably do not need to know details line and verse of pallet performance standards and testing methods, but they should recognize that they are a crucial, behind-the-scenes factor, particularly with some pallet users.

Any confusion over standards and tests underscores the need for pallet manufacturers to communicate clearly with customers, to understand the requirements of their particular application, and to recommend a pallet designed and built for the specific application.

Association. “Standards was one area of concern because we didn’t have any, except for the military.”

The American Society for Testing and Materials (ASTM) now has several standards for wood containers. “The standards we do have are still more design-based than performance-based,” said Elmer. “But most have a section that says you can come up with something that’s equal to or better. Any wood container manufacturer has the option of doing it better with some deviation from the standard, if it is proven by testing, and maybe eventually the standard will be modified.”

A new standard being developed relates to the quality of wood parts. A related military standard was canceled several years ago, but the new standard for wood components is scheduled to be published later this summer.