Cracked exhaust pipe

[Marc DeGirolamo]

I have a Vetterman Stainless exhaust on my RV-4 O-320 engine. My -4 has about 300 hrs on it now and during the annual inspection I noticed (actually it kind of stuck out) that #3 exhaust was cracked at the flange and extended down the pipe about a half inch. Took it off and sent away to get welded.....Welding shop said that #4 was cracked as well (hairline). It was installed so that there was no load at all on the flanges. The socket ball joints seemed to be solid (seized), slip joint was fine when I removed pipe from engine. I am thinking that perhaps it cracked because there was not enough free play (movement) in the pipe....I don't recall reading anywhere that this system had this type of problem.....Has anyone else had this happen to their pipes ? .....thanks