RTJ Flange Gasket & Groove Dimension Calculator
Size API Spec 6A and ASME B16.20 Ring Type Joint (RTJ) metallic gaskets, standard R designations, groove depths, pitch diameters, and Brinell hardness differentials.
Flange Size & Standard Ring Designation
Ring Material & Hardness Limits
ASME B16.20 Dimensions & Hardness
Recommended Tools & Equipment
Tested hardware and components for high reliability
Frequently Asked Questions
Why must an RTJ gasket always be softer than the flange groove?
When an RTJ flange is torqued, metal-to-metal sealing is achieved by coining (plastically deforming) the gasket flanks into the 23° groove walls. If the gasket is equal to or harder than the flange, it will gouge, gall, and permanently deform the flange ring groove, requiring expensive in-situ flange refacing or pipe spool replacement.
What is the key advantage of octagonal vs oval RTJ gaskets?
Oval gaskets contact the 23° groove wall at a curved line-contact, creating high local stresses that require high bolt loads to seal. Octagonal gaskets feature precision flat bevels that match the 23° groove wall angle exactly, providing a uniform planar contact surface that seals at lower bolt preloads and can be reused in emergency turnarounds.
What is an RX pressure-energized ring joint gasket?
The API 6A Type RX gasket is an asymmetric ring designed for pressures up to 5000 psi. Its cross-section is taller than standard R rings and utilizes internal pressure to exert an outward radial force against the groove outer face, increasing the sealing contact stress as fluid pressure rises.