How Should SS 316 Capillary Tubing Be Specified for Instrumentation?

For an instrumentation application requiring small-diameter stainless steel tubing, what are the most important parameters to define when specifying SS 316 capillary welded tubing?

Beyond the material grade, should the specification normally address outside diameter, wall thickness, dimensional tolerances, surface finish, weld quality, and testing requirements?

For welded capillary tubing, I am particularly interested in how engineers evaluate weld integrity and dimensional consistency before installation. Are there specific inspection or testing practices that are commonly used for this type of tubing?

What other factors would experienced engineers consider important when preparing a specification or evaluating tubing from different sources?