Joe,
You could put the contractor out of business by following the advice of 100% RT for all welds. Does the punishment fit the crime?
The specifications (probably) call for visual and pressure test only. In my experience, the specs will give the owner the right to RT whenever they see the need to RT and IF the weld(s) fail, the contractor pays for all NDE. Most of the CW/HW jobs that I have done reference 31.1 but occasionally call for 31.9.
The goal is to ensure that the welds meet a certain acceptance standard and are performed by qualified welders. Because the welds do not have the welders ID on it does not mean that it is a bad weld. It does mean that the contractor did a poor job requiring the welders to ID the welds.
The site QC (before you) should have met with the contractor (pre construction meeting) and gone over the requirements. ID'ing the welds should have been discussed then. The contractor shouldn't have to pay for the GC/QC lack of coordination. Having said that, the contractor should do that without being required to.
One job that I'm on now (as a contractor) has a plumber serving as the mechanical QC. This is the 4th mech. QC. for this project. He is clueless when it comes to CH/HW piping.
My advice is to ensure that all welders were/are qualified, that they provide a WPS, that they are following the WPS (check some fit-ups without prior notice), VT the existing welds, RFI the mechanical engineer and advise him or her of the situation.
Let the contractor know what you require from this point on and you will not accept less than that.
Additionally you could issue a Non Conformance Report.
If the existing welds miserably fail VT then you can require RT. The hydrostatic test will proof test the system.
Again, the goal is to give the owner a quality product that meets a pre established acceptance standard. Not to punish the contractor unnecessarily. The 100% RT suggestion only punishes the contractor and as you correctly stated, all parties dropped the ball. Also, somebody has to PAY for the RT's if the welds pass. Who is going to do that?
For those that haven't dealt with CH/HW projects. RT is rarely required in the job specs except for underground pipe and as a "fear factor" element.
Don't get me wrong. I have no respect for companies that get jobs and do poor work whether in CH/HW, misc. metals, structural etc. We have made over $70,000.00 since June by repairing sub par work by other contractors on those three mentioned trades. We have made new customers as well. I've got some pictures that show how bad of work that some contractors try to get away with.