Oval and Octagonal section Ring type Joints are designed for flanges with standard ring type grooves. These standard shapes are used to seal pressures up to 5,000 psi in accordance with API 6A.
The Octagonal cross section has a higher sealing efficiency than the Oval cross section and is therefore preferred.
The oval section ring joints were originally designed for the now obsolete round bottom groove. Both the Oval and the Octagonal cross section are interchangeable on the flat bottom groove design.
Type R Oval & Octagonal: