The following guidelines are a combination of a list I obtained from Coade years ago, and a list from a consulting engineering company here in Canada. Hope it helps.
In case it is of interest, we're conducting a CAESAR II pipe stress seminar in Calgary, AB, June 19 - 23.

When to Perform Pipe Stress Analysis:
1. Lines that are 3 inch and larger that are:
a) connected to rotating equipment,
b) subject to differential settlement of connected equipment and/or supports,
c) with temperatures less than 20 F.
2. Lines connected to reciprocating equipment such as suction and discharge lines from reciprocating compressors.
3. Lines 4 inches and larger connected to air coolers, steam generators or fired heater tube sections.
4. All size lines with temperatures of 600 F and higher.
5. Welded lines 6 inches and larger at a design temperature of 350 F or higher.
6. Lines 16 inches and larger (any temperature differential), because of large F=P*A thrust forces
7. High pressure lines (over 2000 psi), although pressures over 1500 psi are sometimes a problem, particularly with restraint arrangements.
8. Lines subject to external pressure.
9. Thin-walled pipe or ducting of 18 inch diameter or larger, having an outside diameter over wall thickness ratio of more than 90.
10. Lines requiring proprietary expansion devices, such as expansion joints or victaulic couplings.
11. Underground process lines. Pressures greater than 1000 psi in underground piping inevitably generates high thrust forces, even at very low expansion temperature differentials. Attention is required on burial techniques, changes in direction, ground entry/exit, or connection to equipment or tanks. Other examples include pump/booster stations, terminals, meter stations and s****er traps.
12. Internally lined process piping & jacketed piping.
13. Lines in critical service.
14. Pressure relief systems. Also relief valve stacks with an inlet pressure greater than 150 psi.
15. Branch lines tie-ins or matched size, particularly relief systems tied together or large branch piping of same size or close to piping being connected.