s how stress is perceived by the listener, p r i m a r i l y t h r o u g h p i t c h changes. It shows h o w i n f l e c t i o n s s t r e s s c e r t a i n w o r d s in a sentence~ and that a w o r d ' s internal stress (accent) a f f e c t s how these i n f l e c t i o n s are c o n s t r u c t e d . An i m p l e m e n t a t i o n of these f i n d i n g s to add stress to c o m p u t e r speech is shown, c o m p a r e d with s i m i l a r work, and evaluated.

In order to assess postulated defects in the butt weld joining a 90 degree elbow to a seamless straight pipe, both axial and hoop stress components at this position are required. ASME III NB-3685 provides a method of calculating elbow stresses. However, this gives the maximum stress values in the elbow and applies to the central section of the bend. If these values are directly used in the defect assessments of welds at the ends of the elbow, the assessment results will be overly conservative. In order to obtain appropriate defect assessment results, more accurate axial and hoop stress distributions at the elbow ends are desirable. In this paper, the axial and hoop stress distributions at the elbow ends are predicted by deriving generalized stress relationships between the elbow end and the central section of the elbow, based on detailed finite element analyses and ASME III NB-3685 calculations. In order to do so, a series of small displacement elastic 3D finite element analyses have been performed. The finite element results were then compared with the ASME III NB-3685 stress predictions. Finally, the axial and hoop stress relationships between the elbow end and the central section of the elbow for internal pressure, in-plane moment and out-of-plane moment were derived. A comparison of the calculated stress values using the derived equations, the finite element analysis results and the ASME III NB-3685 stress calculations confirms that the derived stress relationships are appropriate to predict the axial and hoop stresses at the elbow ends. The objective of this paper is to show: 1) the ASME III NB-3685 stress calculations agree well with the 3D finite element analysis results at the central section of the elbow and 2) the derived stress relationships are appropriate to predict the axial and hoop stresses at the elbow ends.

In order to ensure the integrity of a seamless butt-welding elbow, both the central section and ends of the elbow need to be assessed, as the maximum stress is normally located at the central section of the elbow but there are no welding residual stresses. Furthermore, at the ends (welds) of the elbow, very high welding residual stresses exist if the welds have not been post weld heat treated but the primary stresses induced by the internal pressure and system moments are lower. For a 90 degree elbow welded to seamless straight pipe, both maximum axial and hoop stress components in the elbow can be calculated using ASME III NB-3685. At the ends of the elbow, axial and hoop stress components can be obtained using the stress equations presented in the paper of PVP2010-25055. In this paper, a series of limiting defect assessments have been carried out on an elbow assuming a postulated axial external defect as follows: • A number of assessments have been conducted directly using the axial and hoop stresses calculated based on ASME III NB-3685 for different system moments. • A series of assessments have been carried out using the axial and hoop stresses calculated using the stress equations presented in the paper of PVP2010-25055, a wide range of welding residual stresses and different system moments. A comparison of the assessment results in the elbow and at the ends of the elbow shows that when system moments are relatively low and the welding residual stress is high, the limiting defect size is located at the ends of the elbow; when the system moments are high and the welding residual stress is low the limiting defect size is located at the central section of the elbow. Therefore, it can be concluded that when assessing an elbow, the assessments should be carried out at both the central section and the ends of the elbow, in order to ensure the integrity of the elbow.