preservatives on the amount of twisting. Hans Burger's (3) studies in Switzerland established a 

 correlation between spiral grain and poles twisting in service. 



COOPERATIVE STUDIES ^ 



Because of the lack of information in this country on pole twisting, several studies were 

 made of various phases of the problem in cooperation with pole producers . Each of these 

 studies is here discussed separately. The first study set out to determine what might be the 

 cause of twisting of poles in service. It soon pinpointed spiral grain, and all subsequent studies 

 were concerned with this property. The second study attempted to find a practical method for 

 detecting spiral grain in unpeeled poles . The third study surveyed the occurrence of spiral 

 grain in poles in four pole yards in northern Idaho and northeastern Washington. The fourth 

 study tried to determine the effects of altitude and stand density on spiral grain in live pole -size 

 trees. The fifth study established a larch pole farm at Newport, Washington, to determine the 

 effect of spiral grain on twisting of poles. A sixth study, to be reported later, established a 

 pole farm at Libby, Montana, somewhat similar to the Newport pole farm; but it included three 

 species rather than only the one species at Newport. Western larch (Larix occidentalis Nutt.) 

 was chosen as the study species for all five studies reported here because it was available at the 

 different pole -processing plants and because of its wide acceptance as a pole species. However, 

 it is believed that the information obtained applies to other pole species. 



Relation Between Spiral Grain and Twisting 



The first study was made to determine, if possible, what caused poles to twist when in 

 service in power transmission lines. This investigation, made in the spring of 1952, involved 

 the inspection of poles in several transmission lines. The poles were examined in detail to 

 discover any possible cause of twisting, and spiral grain appeared to be the major cause. 

 Consequently the following discussion is concerned only with this property. 



Two hundred and ninety western larch poles in four transmission lines were examined 

 during this study. The lines were selected on the basis of historical knowledge of the poles 

 used in each line. For each pole, information was obtained on the relation between the degree 

 of spiral grain on the pole surface and the twisting of the pole in place. In addition, historical 

 data provided information regarding the effect of seasoning on the subsequent amount and 

 direction of twisting in the spiral -grained poles. 



The lines inspected were typical; that is, the pole lengths ranged from 30 to 60 feet with 

 half of the poles being imder 45 feet and the remainder over 45 feet in length. The poles had all 

 been butt treated; however, the length of air seasoning time, prior to treatment, varied among 

 the different pole lines. The poles in one line had been butt treated green; in a second line, they 

 has been air seasoned 6 months prior to treatment; in the third line, the poles had been air sea- 

 soned 22 months before butt treating; no definite seasoning information was available on the poles 

 in the fourth line . 



The following companies cooperated in the first, second, third, and fifth studies described 

 here: Poles, Inc., Spokane, Wash.; B. J. Carney and Co. , Spokane, Wash.; andSchaefer- 

 Hitchcock Co. , Sandpoint, Idaho. The J. Neils Lumber Co., Libby, Mont., cooperated in the 

 fourth and sixth studies . 



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