Fracture prediction of structures manufactured from high strength engineering steels is a high priority in key industries. In this work residual stress (RS) effects on creep crack initiation and growth are studied. In order to quantify the RS magnitude and RS relaxation during creep, measurements are performed along the crack direction in prestressed components. Recent studies have been performed for RS measurement of austenitic stainless steels of 347 and 316L. A number of measurements have been made at ISIS on large (25 mm thick) pre-compressed C(T) specimens but this research focuses on small (18 mm thick) pre-tensioned C(T) specimen in addition to pre-compressed specimens. This will allow direct comparison with creep fracture tests on standard specimens. The research will also investigate the effect of prestress direction (compression vs. tension) and magnitude on cracking behaviour.