Some specific types of branch connections are presumed to be acceptable. This, of course, includes listed fittings (e.g., ASME B16.9 tees and MSS SP-97 branch connection fittings). It also includes the following:
For branch connections DN 50 (NPS 2) or less that do not exceed one-fourth of the nominal size of the run pipe, threaded or socket welding couplings or half-couplings (Class 2000 or greater) are presumed to provide sufficient reinforcement as long as the minimum thickness of the coupling is at least as thick as the branch pipe.
Branch connection fittings qualified per para. 304.7.2 are acceptable.