They can always meet the original specification, but it may cost more in terms of time and money than they expected. In other words, the contractor bid the job low hoping to side step the testing requirements altogether.
When you say bell and spigot, I am thinking of the cement lined ductile iron pipe used for municipal water supply. Is this simply a lap joint welded inside and out? I am not familiar with the system you are using.
Al
"stick with what was specified" is a very good response in my opinion. Trying to impose a harsher spec AFTER the ink on the signatures has dried is a very disputable action. And probably a big win for the contractor after major headaches for all involved.
I see a lot of what we call "junk pipe" spec'd way too lax. Then, when the owner gets a product that's either unaccepatable or borderline, they have already made their bed. Spec the work properly from the get go using "My Patented Goldilocks Principle (not too hard, not too soft, just right)" (that requires some engineering with real world experience with the specific type of project, not "OK, we can handle this" local civil engineering, up front cost = less cost downstream) and the owner actually gets what he/she expected (required) in the first place.
Write little or too soft specs and you just opened the door for a poor end product done by fly-by-night "sure, we can weld that pipe" hungry contractors. Same thing the opposite direction, write specs befitting a 42" 2500 psi gas trans line and the owner will overpay to a large extent for a 150 psi water line.
I do know that if I bid the work, got the work, then the specs changed in the middle of the job my attorney would be a busy, busy man.
If the owner is unhappy with the weld quality they can only fall back on the original documents, imo. Those can be enforced to the last molecule, but stepping beyond those specs is just dumb, poor planning and a long process involving either an arbitrator or a court.
Sounds to me more like a situation where the required amount of water, and the cost of handling that water pre and post test, has turned out to be a shock to the owners. If the welds are making visual, and the 100 psi annular space test then chances are they will happily pass the hydro.
Some utilities go in without a real understanding of the logistics involved in big bore hydro. Specially the discharge end of things.
With the limited information here, I may be way, way off so take it or leave it.
JT