post weld heat treated

What is the temperature and pressure of the steam, please?

pressure 270 psi and temperature 250 deg. centegrades

I do not recall seeing any "hard" rules for this in any repair code - thinking out loud, the code writers are probably of the mindset that the user would fix the root cause of the problem before performing multiple repairs.

The issue is not so much the multiple PWHT operations (if done correctly), which can cause toughness/impact strength problems, but the effects of multiple welding. A general rule that we follow is that only 2-3 welding repairs before we start looking into local hardness and microstructure testing - and/or just outright replace a length of the main pipe, or vessel plate, or ...........

After a couple/few welding repairs you start to get some pretty unpredictable grain/micro structure changes that can (will) have an adverse effect on corrosion resistance, hardness, ductility, notch toughness, .............

Of course this all depends on good judgement and materials/service involved. We are a lot more cautious with high-pressure hydrogen versus low pressure cooling water.