I have a pressure surge of 30 barg on a24" line and i am finding information on calculation of loads at changes in direction scarce. Does anyone know where I can get a copy of a paper written by T. H. Chen, "Evaluating Surge Pressures in Piping System", ER&E Report EE.105E.84, December 1984. or any other ref which would shed some light on the problem.

Formulas with reference to Piping Handbook Crocker & King can be found in the Applications Guide. Many other books covering Hydraulic Transient topics will be usefull. One is by Wylie and Streeter.
Kellogg's Design of Piping Systems also covers the subject.