The OP's question implied he had NDE requirements that he should have been putting before hydro, so we all assumed welding was the method he would use to make the joints.
The only escape clause I know of is, if you are NOT doing any welding, brazing on any joints in the system and of course not working with elevated temperatures or high cyclic stress, etc. If you are clamping, or screwing pipe together or somehow otherwise making joints that require no welding and brazing, then only a leak test is required; see paragraph 345. If that's the case, no NDE is required at all, so do the leak test before you do any NDE
If you had a piping system with such a low probability of failure as you describe (welded or not) and that little a chance of doing damage, or causing harm to persons, company, or property and repair cost would be insignificant, then why worry about any testing at all because its doubtful that your piping would be covered by any code or regulation anyway. So if no code or requlation applies and the engineering specs don't specify NDE and, if the owner agrees with you, go for it.
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"The problem isn't working out the equation,
its finding the answer to the real question." BigInch