PetroStreet

1) What is the difference between Stub-ins and Stub-ons . Kindly state the difference using Figures?

2) Where do we prefer Stub - ins and where do we prefer Stub-ons?typical applications?

Regards

1) See Fig. 328.5.4D in ASME B31.3. (1) is a stub-on type and (2) is a stub-in
2) Both are acceptable as per code considering that you make the right calculations as per your design conditions. Normally., stub-in connections are preferred where you have high pressure and high temperature service.