No. I think that is accurate. But there were other issues too. The rubber "O" ring material was not elastic at the temperature it was being used at, the shuttle was launched on a colder day than it had ever been launched, etc. The presence of an asbestos backing material would have reduced the risk of burn through in that context, but the seal design was used beyond it's rated capability.
In fairness to the decision makers, "rated capability" in this case is a label I assign in hindsight. The seal is complex, and didn't have a clear "rating" like we see on everyday component parts of household and industrial appliances. But the decision makers are at fault, because the booster designers asserted "unsafe to launch."
http://www.centennialofflight.gov/essay/SPACEFLIGHT/challenger/SP26.htm <- Other issues
http://vesuvius.jsc.nasa.gov/er/seh/explode.html <- Verbal description of seal changes
http://www.engineering.com/content/ContentDisplay?contentId=41009024 <- Human decision-making errors
http://cbsnews.cbs.com/network/news/space/51Lchap11recommendations.html <- More
On Sept. 15, 1980, the solid rocket booster joints were classified as criticality 1R, meaning the system was redundant because of the secondary O-ring. Even so, the wording of the critical items list left much room for doubt: "Redundancy of the secondary field joint seal cannot be verified after motor case pressure reaches approximately 40 percent of maximum expected operating pressure." The joint was classified as criticality 1R until December 1982 when it was changed to criticality 1. Two events prompted the change: the switch to a non-asbestos insulating putty - the original manufacturer had discontinued production - and the results of tests in May 1982 that finally convinced Marshall management that the secondary O-ring would not function after motor pressurization. Criticality 1 systems are defined as those in which a single failure results in loss of mission, vehicle and crew. Even though the classification was changed, NASA engineers and their counterparts at Morton Thiokol still considered the joint redundant through the ignition transient. The Rogers Commission found this to be a fatal flaw in judgment.
O rings should never have been used in this application. They are notoriously deficient in high pressure joints, doubly so for flexible ones. They should have used a pressure energized double chevron lip seal, which is flexible enough to compensate for SRB joint eccentricity. I have seen these seals hold over 5,000 psi. I was severely disappointed after the Challenger disaster to see what NASA had allowed to be used in our spacecraft.
Thanks, for the Indepth/clear explanations. :D