Depending on the pressures and volumes, I would expect the pressure-containing elements to be covered by the pressure systems regs and associated codes, guidance, etc. which will include relevent BS or international standards. Of course, that statement doesn't necessarily get you much further forward as inspections of pressure systems are typically mostly linked to operating conditions and deterioration mechanisms, i.e. they are risk-based.
One thing to definitely beware of is taking pressure systems apart just so as to inspect them - evidence is that this is at least as likely to introduce a fault as to find one. If the systems have pretty high pressures, then good industry practice is to have in place systems for recording when and who by the joints were re-made and (of course) to re-test them. If you can't identify any corrosion mechanism for the pipework, as I would think might be typical for such a rig (operating in a benign environment and with inert fluids?), then maybe no specific NDT-type inspection is warrented? Obviously you should inspect in some way for early signs of the particular failure mode(s) associated with the minor incident - but you don't say what these were.