Strain Gage Test at the Threaded Closure on a Thirty-Inch Pressure Vessel

Abstract

A study has been made-utilizing the strain-gage measurement method to determine the stresses experienced by the internal threaded areas of the closure on a 30-inch pressure vessel at the Y-12 Plant. This test was performed to gain information that can be used for: (1) determining the maximum stress levels at operational pressures, (2) estimating the useful operational life of the vessel at various stress levels, (3) making a comparison with photoelastic studies that were obtained on models of a vessel of very similar design, and (4) estimating the operational pressure parameters of the proposed alterations to the vessel. Measurements were obtainedby utilizing metal-film gages having a gage length of 0. 050 inch and a width of 0. 044 inch. These gages were secured in the root of the threads with Eastman 910 cement. Measuring accessibility was attained using enameled wire of Size 34 AWG,spot cemented into the root of the • thread. Conventional strain readout instrumentation was used. The highest strains measured were obtained in the thread closest to the Internal pressurlz.ed area. These values were approximately 3470 microinches/inch. Results of the test indicate that reliable information can be obtained by this strain-measuring technique provided the installation of the gages and lead wires is given close attention.

Brittle failure of a large, high-pressure isostat, and a comparison analysis of its twin vessel

“…The 0.156-in (3.96 mm) clearance at the root of the thread was sufficient for installing miniature strain gages in the original installation, as illustrated in Figures 13 through 18. (1,12) Subsequently, in the modified vessel (a gas autoclave), strain gages were again installed, as indicated in Figures 19 and 20. Table 2 gives the recorded strain levels in the original tests;(l2) Table 3 lists the significant strain levels in the test of the modified vessel about ten years later.…”