Nondestructive Testing Technique to Quantify Deterioration from Marine Borer Attack in Sitka Spruce and Western Hemlock Logs

Book excerpt: Stress-wave nondestructive evaluation (NDE) techniques are used widely in the forest products industry--from the grading of wood veneer to inspection of timber structures. Inspection professionals frequently use stress-wave NDE techniques to locate internal voids and decayed or deteriorated areas in large timbers. Although these techniques have proven useful, little information exists concerning the relationship between stress-wave parameters and deterioration observed as a consequence of marine borer attack. In this pilot test, we examined the relationship between stress-wave transmission time and the quality of wood in Sitka spruce and western hemlock logs that had varying degrees of deterioration as a consequence of attack from marine borers. Stress-wave transmission time, perpendicular to grain, was measured at several locations on each log. The logs were then sawn into lumber, which was then visually evaluated. A relationship was observed between stress-wave transmission time and deterioration of the logs and the yield of lumber from the logs.