Happy Birthday, POPS

From the Hazardous Cargo Bulletin, August 2000

As the US steel drum community approaches the tenth anniversary of POPS, Howard Skolnik asks whether its goals have been met

It is nearly 10 years since the concept of Performance Oriented Packaging (POPS) for transporting hazardous materials was introduced in the US. As with any corrective process, POPS demonstrates that with each solution comes a new set of problems.

For more than 40 years, Specification Packaging was the method of ensuring that packaging intended for use with dangerous goods would be made in accordance with the requirements of the US Department of Transportation (DOT). The procedure was introduced in order to unify packaging that until then was available in many design types, dimensional standards, metal thicknesses and test criteria. Specific construction guidelines were addressed and, once implemented, dangerous goods packaging worldwide followed these precise guidelines. An obvious advantage to this Standards programme was that in every country, for every design type, drums were virtually available with comparable characteristics. There-fore, shopping for competitive products was uniform. On the negative side, the uniformity requirement did limit product innovations that were available as technology progressed and under the Specification Standards system exemptions were required for variations. The exemption process was lengthy and, in most cases, rejected.

In the 1970s, a new Standards procedure in Europe started to turn the heads of both packaging manufacturers and end users. Called Performance Oriented Packaging Standards (POPS), this new Standard allowed for integrating technical and manufacturing advancements into packaging without having to petition a competent authority for an exemption. POPS established four primary tests: drop, hydrostatic pressure, leakproofness and stack. Design specifications for an acceptable container were removed and for most products the only requirement was the ability for a container to pass these tests successfully. With POPS adopted in Europe and the UK in the late 1970s, the US first introduced POPS in 1991 and made it mandatory in 1996.

Within the first years of implementation, it became clear that there were new design characteristics which could influence drum performance. The conventional double (box) seam gave way to the triple (round) seam in which seven layers of chime replaced five layers; round and square sponge rubber gaskets were replaced by new gasket designs and material compounds and new closure ring contours and styles were introduced.

Most significantly, these innovative features allowed for a reduction in metal thickness, thereby reducing the raw material requirement and cost. More recently, the introduction of modified expansion rings and body diameter has yielded drums which fit four-across in a freight container and thereby increase shipping capacity.

The one major US deviation from the European Standards programme was with regard to the method of certification testing. While the European Standard required that individual drum types be tested once by a recognized third-party testing laboratory, the US provided an alternative: manufacturers, remanufacturers and reconditioners could self-certify their packagings, with the proviso that each design type should be retested at least annually.

Thus, the resulting package selection criteria and liability shifted from the container seller to the container filler. These fillers needed to learn the details of container nomenclature, differing Packing Group hazard levels (I, II, III), determination of specific gravity and the conversion of pound measurements to kilograms. 
In addition, end users also had to learn how to discern non-similar containers that appeared visually to be similar, identify and confirm valid markings in metric meassurements, keep from interchanging removable drum parts (i.e. plugs, rings, gaskets) and most critically, close each drum according to the closure instruction given by each container manufacturer.


As we close the first decade of POPS implementation, it is appropriate to review the achievements of this new Standards format and thus modify the weaknesses and enhance the strengths. Of particular interest, the POPS format offered a greater understanding of performance criteria relative to the use of lighter gauge metal.

Though many test criteria were not hampered by the thickness reduction, material handling issues did suffer as a result of this cutback. Also, the reduced metal thickness lead to a greater need for proper blocking and bracing during transport as the drums were less able to resist in-transit movements. Further, DOT will soon implement Form 5800, an incident tracking log for all dangerous goods movements within the US, that will validate required performance tests to in-field movements.

The use of the POPS format also indicated an increase in integrity and performance of top and bottom seams as well as the need to keep integral drum parts intact with their original design type. Manufacturers, remanufacturers and reconditioners have also learned to document and measure the critical characteristics of each closure system and achieving 'macho marks' appears to be less important then producing containers that generously pass the performance tests.

As a result of work carried out by DOT's Tobyhanna Test Laboratory, container manufacturers have learned the difference between confident and marginal design type options and now offer products that meet the daily rigours of use rather then the occasional peaks of performance.


As we enter the second decade of POPS, there already are hurdles that need to be resolved. Of the seven leading regulatory institutions that oversea dangerous goods movements (ADR, IATA, ICAO, IMO, RID, UN and US DOT), harmonisation of the requirements will continue to be challenge to the global community.

With regard to metal thickness, some manufacturers have been too aggressive in the application of thin steel to dangerous goods containers. Though the containers can pass performance tests in a laboratory setting, these same containers suffer greatly once the filled package is exposed to material handling.

For this reason, the DOT has discussed the re-establishment of minimum standards for dangerous goods drums. Also, a possible fifth and sixth test, vibration and material handling, will be added to the required test roster.

While universal closing procedure for open and closed head drums is under discussion, manufacturers are creating new types of ring closure systems that can be UN-closed without the use of calibrating tools.

The recently retired director of RSPA, Al Roberts, has been quoted as saying that "the safety record for hazardous materials shipments governed by US DOT is the highest in the world". In the steel drum community, the ultimate POPS goal is to perpetuate this leadership for global container integrity and safety.

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