A
Th e
Component Manufacturing dverti$er
Don’t Forget! You Saw it in the
Adverti$er
March 2019 #11236 Page #34
How Should Defects Be Recorded When Inspecting a Critical Plate?
A
critical plate is a plate with a Joint Stress Index of 80% or greater. The ANSI/TPI 1–2014 Standard stipulates that critical plate inspections must be conducted when completing the three inspections per station/per shift/per week requirement. On average, the standard requires one critical inspection for each inspection made that week. Because some trusses will not have any critical plates though, several additional inspections will need to be made on the other trusses with multiple critical plates. The critical plate inspection can be performed using the Plate Placement Method (PPM). The PPM is a tool that speeds this examination by generating a template within the truss design software used to design the component. In lieu of the PPM, an old school method can be employed by counting and recording teeth and comparing “good teeth,” teeth that are installed effectively, and “bad teeth,” those teeth that are pressed in defect areas or are damaged to the point the tooth is ineffective. Recording defects is one aspect of using the PPM. During the inspection, defects need to be recorded to provide historical data. In example “a” shown in the figure, a knot defect is recorded as a percentage of the defect circle. While this clearly records the defect situation, it doesn’t provide the reviewer with enough information to know the actual defect situation. In contrast, example “b” shows the same defect, and it is recorded correctly. The template is placed over the defect and, using a marker, the profile of the defect is recorded within the circle on the PPM paperwork. The shading can be used to emphasize this condition. After the defect is recorded, a determination is made as to the percentage, so this information can be recorded into other databases. Continued next page
PHONE: 800-289-5627
Read/Subscribe online at www.componentadvertiser.com
FAX: 800-524-4982