ASME B31.3 would allow service test for services up to 150 psig non-flammable, non toxic services. The 230 psig nitrogen would be over the pressure allowed for simple service test. A 1.5X hydrotest or 1.1X pneumatic test would be the code pressure test /leak test requirement.
If the line sizes are small (NPS-2" or NP 50 mm) then it is probably easy to use bottle high pressure nitrogen to test the piping at 1.1X = 255 psig.
If B31.3 allows testing by N2 for nonflamable nontoxic services operating to 150 psig and N2 test pressure is 1.1 times op press, why would you ever N2 test to anything more than 1.1 x 150=165 psig? In that case I believe what Vladimir says is true, that it is unwarrented to test to 230.
Operating or working? To be precise, neither one. "Design pressure" should be used to determine test pressure.
B31.3 doesn't define "working pressure", "service pressure" or "operating pressure" in the context of test pressure. "Design pressure" is the term used in paragraph 345.5.4 to determine the test pressure. "Design pressure" is defined in 301.2 as the highest gage pressure to which the piping will be subjected. That would include all possible operating and other pressures (except for test pressure and some relatively minor transient excursions above the design pressure from time to time).
345.5 Pneumatic Leak Test
345.5.4 Test Pressure
The test pressure shall be 110% of design pressure.
