Thermal cycle resistant fastening system for refrigerant fitting

A block fitting assembly comprising:

• a first block having a first fastener aperture formed therethrough;
• a second block having a second fastener aperture formed therethrough in axial alignment with the first fastener aperture;
• and
• a fastener extending through the first fastener aperture and the second fastener aperture to couple the first block to the second block, the fastener including a threaded portion and a necked portion, the necked portion having an outer diameter smaller than a minor thread diameter of the threaded portion.

A block fitting assembly comprising:

• a first block having a first fastener aperture formed therethrough;
• a second block having a second fastener aperture formed therethrough in axial alignment with the first fastener aperture, the second fastener aperture including a non-threaded portion disposed adjacent the first fastener aperture and a threaded portion disposed adjacent the non-threaded portion;
• an internally threaded nut configured to engage a face of the first block facing away from the second block;
• and
• a fastener extending through the first fastener aperture and the second fastener aperture to couple the first block to the second block, the fastener including a first threaded portion configured to engage the threaded portion of the second fastener aperture and a second threaded portion configured to engage the nut, the fastener further including a necked portion disposed between the first threaded portion and the second threaded portion having an outer diameter smaller than a minor thread diameter of the first threaded portion.