d. GrayLoc Connector Piping Components - Modeling Approaches, Tips, Techniques used in AutoPIPE

Applies To
Area: model
Original Author:Bentley Technical Support Group


How to model Greyloc connectors in AutoPIPE? 


From GreyLoc:

"Grayloc" type connector--this connector is comprised of facing metal seal ring hubs and an annular clamp assembly. A internal metal sealing ring resembling an inverted "T" in cross section is disposed between the hubs. The clamp assembly fits over the outer annular surface of the two facing hubs and is forced radially inward by making up the clamp bolts to draw the facing hubs together and to compress with the sealing ring rib between the hub surfaces. As the hubs are drawn together by the clamp assembly, the internal seal ring lips engage and deflect against the inner sealing surfaces on the hubs. The deflection of the seal ring lips elastically preloads the lips of the seal ring against the inner sealing surfaces of the hubs thereby forming a preloaded seal. In use, internal pressure acts on the seal ring lips so that the sealing action of the lips is both preloaded and pressure-energized. However, if the internal pressure becomes sufficiently great to cause the facing hubs to be displaced or moved longitudinally of one another, the seal ring lips will lose their sealing ability because the preloading sealing compression between the hubs and the seal is lost. Also the metal seal ring has a 20° (sometimes 25°) bevel so that the seal lips do not radially compensate for movement of the seal lips when the hubs are spread apart from one another

Anything the pipe can take, so as the GRAYLOC Connector

> TENSION - Withstand greater tension loads than conventional ANSI flanges

> BENDING - Numerous independent tests have shown that Grayloc connectors withstand severe bending loads without leaking or loosening.

> COMPRESSION - In normal piping applications, it is not possible to overload the Grayloc connector / seal ring in compression

> CONSERVE SPACE & WEIGHT - Significantly lighter and smaller than a comparably rated ANSI or API ring joint flange connection.

Grayloc’ type pipe connectors may be designed and analyzed in accordance with ASME VIII Div. 1 Appendix 24.

Modeling Approach:

Use one of the suggested modeling approach for a GreyLoc connector:

1. Model as a set of flanges with rigid length. The interesting features here are the tighter the bolting the tighter the connector wedges the faces together, and with the seal ring insert, there is absolutely no accommodations for lateral movement.

2. An alternative would even be to model as a rigid section of pipe with an added weight.

3. Use this approach for concerns about torsional movement between pipes being clamped together.

AutoPIPE has only one component that allows free torsional  movement of a joints face; Flexible Expansion Joint. Review  Model a Sway Brace pipe support WIKI page for similar break away modeling approach; using instead a Flexible joint and insert Moments. Flexible joint, while assuming no lateral, no bending, or axial movement set all Axial, Bending, and Shear stiffness to Rigid. Calculate a  torsional force similar to  Sway Brace support  procedure above. 

See Also

Model Different Types of PIPING Components

Bentley AutoPIPE