Volunteers needed for Working Group to reinstate Useful Method 21 "Sieve analysis of pulpwood chips"

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The method "Sieve analysis of pulpwood chips" is more commonly known as the Williams Chip Size Classification method.  It was developed by the Williams Apparatus Company as a way to measure the size distribution of pulp chips. The Williams method measures primarily length and width of chips using a series of round-hole trays. The size distribution relates to the uniformity of pulping.

TAPPI developed a Suggested  Method for the test in 1945.  It became an Official Standard in 1950.  It was reviewed and revised several times over more than 50 years.  Its last version was as Useful Method UM 21.  When the industry shifted its interest to chip thickness in pulping performance, new classifiers were developed that used parallel rods to measure thickness in combination with round holes. 

Because of this industry shift, there has been little interest in the Williams method, and it was withdrawn from the TAPPI Useful Method set along with a number of others when new guidelines were adopted for the UMs in 2011. It cannot be reinstated until it is reviewed and revised in accordance with the current UM guidelines.

The Williams classifier is still used in the structural panel, biomass and the pulp chip export businesses.  Contracts for current chip export refer to the Williams method in the definition of chip specifications.  Since the method is still in active use by the industry, there is a need to reinstate the method so that it can be distributed and used as a valid contract document. 

If you are interested in participating in a Working Group to review and revise the Williams Chip Classification Method so that it can be submitted for reinstatement, please contact standards@tappi.org by May 15, 2015.

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