That was the opinion of Thiokol. They hired the machine Fabrication shop I worked at to make a guage for the inside of the booster to ensure it was concentric and would fit correctly with the piece it mates with. They were speculating that the fit was not 100% and this was causing a weak spot for the o-ring.

The change of foam on the external tank and the exclusion of asbestos on the o-rings is news to me. I had never heard that before.

If I read those docs correctly, it sounds like someone's trying to pass the buck - blaming politicians and their legislation for requiring greener materials in industry.

If new-formula foam didn't meet specs due to the freon ban in its manufacture, then NASA should have tested adequately and/or found a suitable replacement for that application. Period.

MHO,
Sherwood