How can you exclude the HAZ in a sensitization test?  

I am sorry for not being clear on my message the first time. I am referring only to weld overlays, for butt welds there is no problem and HAZ would be included. For metallurgically bonded clad there would be no problems of dilution too, but what about weld overlaid PQRs?

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668

It appears you are cladding a carbon/low alloy steel with stainless.  I'm more familiar with A-262 Practice A and E, but in my work we always specify a minimum of 2 layers of cladding.  The final exposed surface MUST be in the 2nd layer (controlled by dimension/thickness).

You've probably already done so, but talking with your customer and trying to find out what his reasoning is may be best.

The client is all wrong about the specifications and requirements. The funniest part is we are doing IGC practice B and G 48 for inconel cladding on API 5L X60. I can't believe the client specs asking for IGC tests for inconel cladding since A262 very clearly is for austenitic stainless steels, but well sometime you can do nothing but agree to the client when all your attempts at rationalization fail. We are doing two layers of cladding with different combination of procedures. My problem is as given earlier that if I take the corrosion sample too close to the fusion line, corrosion rates understandably are very high and not indicative of what would be achieved on actual, and if I remove corrsion sample from undiluted weld metal such that one of the surfaces coincides with layer where desired chemistry achieved, client comes down hard on the methodology of removal of the test specimen.

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668

Yes, it sounds like your client is misinformed.  Makes me wonder if it's just some dimbulb "engineer" there, or if they have some other reason.

In my work (nuclear power) we use both stainless and Inconel for cladding, but the environment is high-temp. water (very pure).  This industry has managed to crack (IGSCC) some base metal and one of the weld materials.  I don't know what your environment is, but in general the Inconels don't like a lot of sulfur--at least the nickel majority doesn't!  Chlorides shouldn't be a big problem at ambient temps.

I have done some work on metallurgically claded carbon steel. I have made a teflon container with rubber o-rings only to expose the clad material surface.  This way you do not need to expose the underlying substrate at all.  This worked well in 3 different solutions.  Note this is a modification to the ASTM standard procedure in that the surface area of the exposed clad is smaller.  Hope this helps.