Ferrule with features for softening ferrule crush and related methods

A method for designing a ferrule, the ferrule comprising a first end, a second end, an outside surface extending from the first end to the second end, and an inside surface defining a bore extending along a central axis from the first end to the second end, the method comprising:

• selecting an axial length and a taper angle for a conical section of the ferrule, the conical section extending from the first end toward the second end;
• selecting a nose thickness of the ferrule, wherein the nose thickness is defined between the inside surface and a sealing region of the outside surface along a radial direction orthogonal to the central axis, the sealing region being located at or near the first end;
• selecting a number of annular grooves to form on the outer surface in the conical section, wherein the number is two or greater;
• selecting a plurality of groove thicknesses of the ferrule at the respective grooves, wherein each groove thickness is defined between the inside surface and the outside surface at the corresponding groove along the radial direction orthogonal to the central axis, and one or more of the groove thicknesses are greater than the nose thickness;
• forming the conical section such that the conical section has the selected axial length and the selected taper angle, and the ferrule has the selected nose thickness, wherein the conical section comprises two or more collapse zones between the sealing region and the second end;
• and
• forming the selected number of grooves in the conical section such that the ferrule has the groove thicknesses selected for the respective grooves,
• wherein the sealing region and collapse zones are configured to axially collapse in sequential order in response to axial compression of the ferrule.

A ferrule, comprising:

• a first end surface;
• a second end surface spaced from the first end surface along a central axis;
• a lateral outside surface surrounding the central axis and extending from the first end surface to the second end surface, the lateral outside surface defining an outer radius of the ferrule along a radial direction orthogonal to the central axis;
• and
• an inside surface surrounding the central axis and extending from the first end surface to the second end surface, the inside surface defining a bore extending along the central axis and open at the first end surface and the second end surface, wherein:
• the ferrule comprises a conical section extending from the first end surface toward the second end surface, such that the outer radius increases in a direction away from the first end surface;
• the lateral outside surface comprises a sealing region at or near the first end surface, the sealing region being configured to form a sealing interface with a fitting in response to axial compression of the ferrule;
• the conical section comprises two or more collapse zones between the sealing region and the second end surface, the collapse zones being axially spaced from each other and from the sealing region,
• the thickness successively increases at each collapse zone in a direction away from the first end surface;
• and
• the sealing region and the collapse zones are configured to axially collapse in sequential order in response to axial compression of the ferrule, starting with the sealing region and followed by each successive collapse zone.