Re: 2015 Rules Submission and Discussion
Posted: Thu Feb 05, 2015 8:54 am
I think its worth a good discussion at the rules meeting as to how we grandfather existing cages and ones that are built to other acceptable standards, and what from the past just isnt going to fly.
I think John took a good stab at doing that in 7 and 8.
If it isnt already, we need to be sure it is clear that materials we accepted in the past are not to be used for construction from this point forward. John's mention of things like A500 Class A and A513 type 1 are an acknowledgement that such materials are below our new construction requirements but where they have been previously accepted they will continue to be for existing cars. That statement does specifically not limit acceptability of existing cages using these materials to those on cars that have previously hillclimbed with us and been accepted as suitable cages, only that they were built before this rule goes into effect. We may want to further limit this...or not. It is very clear that cages built from materials below that listed in 7 as "marginal" are no longer going to be accepted regardless of whether they previously raced with us or not.
Schedule 40 pipe is not considered structural tubing at all but I am sure it has been used for roll cages. It is about 50% thicker (in the 1.5" nominal size) and with larger OD than our requirement for 1.75" tubing, but soft... being below the proposed minimum strength at about the same strength numbers as ASTM 1008-1010. So the added thickness and diameter compensates some for the softer metal. Based on that, I think it it does fall into the same general category John labeled "marginal" and "accepted principally for existing" cages. Schedule 10 on the other hand, possesses the same low tensile and yield strength numbers 40, but is just about the same thickness as we require of suitable tubing. So 10 really should be unacceptable.
I think John took a good stab at doing that in 7 and 8.
If it isnt already, we need to be sure it is clear that materials we accepted in the past are not to be used for construction from this point forward. John's mention of things like A500 Class A and A513 type 1 are an acknowledgement that such materials are below our new construction requirements but where they have been previously accepted they will continue to be for existing cars. That statement does specifically not limit acceptability of existing cages using these materials to those on cars that have previously hillclimbed with us and been accepted as suitable cages, only that they were built before this rule goes into effect. We may want to further limit this...or not. It is very clear that cages built from materials below that listed in 7 as "marginal" are no longer going to be accepted regardless of whether they previously raced with us or not.
Schedule 40 pipe is not considered structural tubing at all but I am sure it has been used for roll cages. It is about 50% thicker (in the 1.5" nominal size) and with larger OD than our requirement for 1.75" tubing, but soft... being below the proposed minimum strength at about the same strength numbers as ASTM 1008-1010. So the added thickness and diameter compensates some for the softer metal. Based on that, I think it it does fall into the same general category John labeled "marginal" and "accepted principally for existing" cages. Schedule 10 on the other hand, possesses the same low tensile and yield strength numbers 40, but is just about the same thickness as we require of suitable tubing. So 10 really should be unacceptable.