Shuttle SRB Hold-Down Bolt

The museum displays a Shuttle solid rocket booster hold-down bolt and frangible nut.

Four such bolts held down attached each SRB to the mobile launcher platform, each attaching to one of the hold-down posts on the SRB's aft skirt.

Each bolt had a nut at each end; the top nut was frangible. Each nut contained two "NASA standard detonators" which ignited at when the SRBs were ignited, severing the top, frangible nuts and releasing the space vehicle.

Each frangible nut was covered by a blast container which prevented the halves of the nuts from damaging the Shuttle stack. Based on SRB recovery photos, it appears that these blast containers remained attached to the SRB throughout the flight.

The SRB bolts were 28 inches long and 3.5 inches in diameter. I was unable to determine the outer diameter of the nuts.

See this NASASpaceFlight post for a diagram detailing how the hold-down bolts were installed.