aumechengr,
Taken as a minimum requirement, 0.25 mm thickness should be o.k. for stainless steel jacketing.
Local standards or client's specifications may require higher values.
e.g.
German Standard DIN 4140 requires 0.5mm to 0.8mm minimum thickness in relation to the insulation circumference;
NORSOK standard R-004 requires 0.5mm to 0.7mm in relation to the pipe diameter;
Some Industry Practices (e.g. EXXON) require 0.25mm minimum thickness with thermal insulation, and 0,40mm with noise or noise&thermal insulation.
A minimum thickness for plastic jacketing is not available to me.