Home Forums General Discussion Specifications Difficulty with set-up for Almen test

I received a call from someone having difficulty setting up the Almen holder that simulates the actual part being peened. The part is tubular with flanges welded at each end which are to be peened. A 5/16 nozzle with 4" standoff which produces about a 1.25inch blast patteren is used to peen the flange joint as the tube is rotated. The nozzle is held stationary.
The blast pattern will not completely cover the Almen strip. So, this raises several questions:
1. will the partially covered strip deflection be accurate compared to a fully covered strip?
2. If not, then what can be done in the set up to satisfy the specification AMS-S-13165?

I suggest you try what worked for me when I had a similar problem. (1) Set the Almen block and strip so the spray pattern hits the center area of the strip - measure the arc height. (2) Peen another strip of which you peen the center and then move sideways and peen one end and then move the other way and peen the other end. Compare arc heights of the center peened strip with the fully peened strip. If they are the same, just use that system. If the center peened strip has a lower arc height, use the ratio of arc heights to compensate - record the ratio as a "Shaded Strip Compensation" - That should satisfy an auditor.
Pete Bailey