Hi guys… first of all, I am sorry for my English.
Somebody can guide me how to make an O Ring flange. For example, I have an acrylic tube with inner diameter of 94 mm. what is the good size of O Ring that I must buy? and how about the dimension of O Ring flange must be?
Thank you for your attention. 
Go get this document. It is the Parker O-Ring handbook. I have made many high pressure seals using the guidelines in the document. There are critical dimensions defined for “Flange” style seals etc.
Overall the handbook is a very good read into the world of static and dynamic seals.
Hi Harold, thank’s for your information.