Unless you can prove that there are no concerns with creep using the simplified methods outlined in the May 1993 issue of the newsletter (and keeping in mind pressure stress and local discontinuities such as weld details and pipe peaking), then you will need to use a more comprehensive method of analysis for creep, such as the one outlined in API RP579-1 / ASME FFS-1.
An example of such an analysis is shown in the paper: Brown, W., Prager, M., Wrobel, S., 2010, “A Case Study on the Effect of Peaked Pipe Welds on Piping Life Expectancy", Proceedings of the ASME PVP 2010, ASME, Seattle, WA, USA, PVP2010-25795
Regards,
Warren