Well, if it's only there as a retaining function without impact on the sealing function I wouldn't worry about it. If it were however there as a sort of tensioner it would be a different aspect. But by the looks of it I would think retaining.. Would be nice if someone could confirm out of experience.
To be clear, I am talking about the one arctic is pointing at in this picture:
Any feedback on the seal? Or should I just not worry to much about it and just put the o-ring on the pipe and get it in there?
I would just think an O-ring needs some kind of support to function, hence why I was wondering about the shoulder on the pipe. But it could also be there only to keep the pipe securely in position with the clip.
When I removed the pipe one was against the shoulder (leaking one) and one was down the fuel rail cavity. So yes.. made me start thinking about it..