reliefvalve.pdf

ENGINEERING MATERIALS 1669 Foxgrove Court Upland, CA 91784 909.260.5633 HTTP://EMAT.ENG.HMC.EDU ENGINEERING MATERIALS Page 1 FRACTURE ANALYSIS REPORT RELIEF VALVE P/N B126 S/N 0016 Submitted To: Claire Lessiau Project Engineer Ausco, Inc. 820 Port Washington Blvd Port Washington, NY 11050 Submitted By: Joseph King Engineering Materials 1669 Foxgrove Upland, CA 91784 October 6, 2005 ENGINEERING MATERIALS Page 2 SUMMARY Relief valve B126 S/N 0016 failed due to a combination of fatigue and corrosion fatigue. This failure mode is consistent with the estimated operational stresses. INTRODUCTION Subject relief valve failed during endurance testing after being exposed to reverse loading. The valve was forwarded with a request to supply a metallurgical report on the fracture of the aluminum 7075 T6 body. The following additional information was provided: spring constant = 410 lb/in, working height of the spring estimated to be 1.542 inches, max exposure pressure = 3200 psi. EXAMINATION The components provided for examination are presented in Figure 1. The main components involved in the failure are shown in Figure 2. The part identification inscribed on the end of the aluminum housing is shown in Figure 3. The free length of the spring was measured and found to be 1.842 inches in length. The total height of the spacers found inside the aluminum housing was measured as 0.170 inches. The outside diameter of the aluminum housing at the fracture surface measured 0.912 to 0.915 inches. Fracture occurred where the aluminum housing attaches to the stainless steel valve body. Various views of both sides of the fracture surface are presented in Figures 4 through 6. Closer views of the fracture surface are presented in Figures 7 and 8. Scanning electron micrographs of the fracture are presented in Figures 9 and 10. A small section of the housing that includes a cross s