At the start of the Shuttle design, RFQs went out to thousands of suppliers in the aerospace sector including a friend & mentor of mine.
Rudolph Kreuger, was an expert is seal design of many types amongst his aerospace contributions. He was a professional engineer and took the proposed rocket stage seal design specifics for the contract seriously and did his calculations.
His conclusion left him concerned about the viability of such a proposed set of conditions for the seal through the range of use conditions so he declined to quote.
The interesting thing to me was that for such a SUPER critical seal, I would have expected that an engineering company would want to find out why a recognized professional engineer sought to not quote the design to learn what they could for future design work.
Doing a critical point analysis ought to be part of every significant highly stressed assembly & I wonder if it was finally done correctly. It seems to have been ignored if it was.
Rudy, died over a quarter century ago, and as far as I know, no one but me and maybe his sons ever knew about this proposed design as he was a very quiet person. Putting yourself into public view can have all sorts of unintended consequences, which I surmise Rudy wanted to avoid.