A BSTRA CT
This paper presents the results of two series of tests performed on 90 ยฐ largeradius elbows. A first series of lO tests was conducted on TU 42 C (equivalent to ASME SA 106 grade B) ferritic steel elbows with an outside diameter-towall thickness ratio of 6" 7. A second series of 15 tests was conducted on Z2 CN 18-10 (equivalent to ASME TP 304 L) austenitic stainless steel elbows with an outside diameter-to-wall thickness ratio of 90. These elbows were subjected to in-plane (opening and closing) and out-of-plane bending moments. Changes in elbow angular deflection and ovalization of the mid-section were recorded as a function of applied moment. Measurements were made well in to the plastic region. Influence of pressure, temperature and cyclic loading was also studied. The tests supplied extensive data on the behaviour of thin-walled austenitic stainless steel elbows when subjected to large displacements, including ability of the elbow to carry the flow under high loadings. Analysis in accordance with the requirements of the RCC-M i was also performed to quantify flow area reduction at stress limits allowed by these rules, in addition to the displacement amplitude margin allowed by the level D service limit criteria with respect to the experimental limit moment. A criteria is proposed which aims to limit secondary stresses under faulted conditions.
NO'rATION
C 2 Class 1 stress index for specific component analysed D O Outside diameter 111