NO, see UG-27 and UW-16,
depends on the thickness of the vessel and t of the nozzle,
you have to run calcs for compensation, if compensation is required, you may add to the weld size weld design or a pad.
ER
There is no requirements depending of the t of the vessel there can be restrictions,
reinforcing may be required on the welds or a particular size of weld throat. if you are not sure, it is best eng practice to run calcs.
see uw16 for exceptions
ER
generalblr and JohnGP had the best answer. I hope to introduce an example;
External load (force and moment for process nozzles) may require the repad (e.g., in WRC 107 calculation) even if UG-36 permits no-repad for small size nozzle opening.
Even though we use the LWN type for 1 1/2" or 2" nozzles, the repads are sometimes required additionally due to the external piping force and moment given by client.