Richman, stainless is going to move, and move a lot when compared with other steel alloys.  In some cases, there may be methods to reduce movement.  From my own experience, what you see on the external surfaces usually has no "direct," i.e., 1:1 correlation to the internal surfaces, which is what you REALLY care about. 

Please don't take the following statement derogatorily, as it may seem I'm "talking down to you" I am not, there are many people in the Forum who have very little experience with these issues so I'm trying to respond in lay terms.

In the simplest of terms, fill an ice tray full of water, take a measurement from the top of the tray.  After the water has completely frozen, take another measurement... you will find that the volume has seemingly reduced, or at least thats what your measurements will tell you.  Is there less water than before?  Perhaps, but it wouldn't be a measurable difference.  It's simply a matter of the water molecules shrinking as they freeze... heat expands, cold reduces... similarly, when weld metal and the interfacing base metal solidifies it has no choice but to shrink... this is what you are seeing. 

You can try sequencing operations to reduce the visible effects but this is entirely up to you and your organization.  Without knowing all of the parameters, I wouldn't attempt to guess whether heat inputs are excessive but can assure you that some shrinkage will occur no matter what you do.  Has any of the inspectors within your organization monitored the welding to verify whether or not they're in compliance with WPS?  That would be the simplest, easiest answer to verify whether or not there are welding concerns.

I apologize again if I seem to talk downward to you, it is surely not intentional but feel like you might be reading things into a situation that are not real.

There seem to be some common mis-conceptions in some of your reasoning.  I'll try to explain and hope I don't get everything confused:

1. I don't see that you mention what grade of stainless steel (or diameter) that you are welding, so for the moment I am assuming that you are welding ordinary austenitic stainless steel (not of the low carbon variety since you mention creep), so if it is something else, all of what is said below may need to go out the window.

2. If the welders don't follow the heat input requirements of the WPS, this is a voilation that needs corrected, and possible remedial action taken in the form of possible testing if there are CVN requirements and heat input is limited.

3. That being said, high heat input (within reason- and unless you have wide weave passes with SMAW, it is probably within reason) on normal non-L grade austenitic stainless steel does not necessarily cause problems in itself unless you are worried about corrosion resistance (and you may be) since slow cooling rates can cause sensetization of the HAZ.  However, even that depends on factors such as the thickness, interpass temperature, and stainless steel composition (such as whether the sst has Ti or Nb).  I don't want to sound like I am supporting the practice of welding with high heat input on stainless steels, but just want to caution the use of the idea that it automatically causes problems.

4. High heat input does not result in more distortion than low heat input.  Actually it is the other way around.  The mis-conception is based on the fact that high heat input commonly results in over-welding, which does increase distortion.  If you have the exact same sized weld, the one with more passes (lower heat input) will result in more distortion.

5. The result of excessive heat input on austenitic stainless does not generally change the hardness since austenitic stainless is not hardenable.  So as mentioned hydrogen cracking from high hardness values are not a concern (there are other cracking concerns with some stainless steels, but not enough information is available to address them for your situtation)

5. All of the above must be tempered with the realization that each situation (and resultant service environment) can be different, and have different needs, so general ideas such as those above have to be evaluated in light of the specific use and expected performance of the stainless steel.

Thanks for that John. I remember on AWS-WHB chapter-7 regarding "Residual stresses and Distortion" but I didn't completely read the content of that chapter, is there somebody from this forum read that? Does this chapter states any criteria of acceptance for the above subject or not?

Thanks.

js55, I am back in Kazakhstan and it's beginning to be very nice, even nicer than at home, in Michigan!  I've not yet spent a Summer here (yet) but the temperatures reach 45C on a routine basis although a dry heat.  I roll out on leave again on May 7th.  We'll be going to 28 days on, 28 days off within the next few months... that will be nice!

I agree completely with your far better explanation than mine... in my opinion, in order for there to be any "real" metallurgical damage, the heat input would have to be so excessive that it might likely even leave visible indications on the parent metal.  Generally speaking, most of us try to keep our interpass down to 350F or lower (for the austenitics) but from my experience, the damage doesnt really get started until one has somewhere around 800F and even at that, for relatively lengthy periods of time.

Richman, for what it's worth, js55 is, in my personal opinion, one of the foremost experts in metallurgy... the original draft of the now published AWS D10.18 "Guide to Welding of Ferritic / Austenitic Duplex Stainless Steel Piping and Tubing" was written almost entirely by js55.

In irony, my contractors frentically called me to the stainless fab shop this afternoon where they are fabbing some 30," Sch. 10 pipe (Type 316L).  They had somewhere around 3/16" hoop shrinkage and the Inspector wanted to run another bead all the way around to lessen the "visible effect" and, as he said, try to offset the density differences when doing RT.  I got a fairly good laugh from it but in the end told them to leave as is, everything would be okay!  By the way, that 3/16" external hoop shrinkage was nearly un-noticable on the ID.