Tie-rod and Pipe Joints

About this unit

Structures and machines often need long rods held under adjustable tension, and pipelines need joints that are strong, leak-proof and easy to open. This unit covers two such joints: the turnbuckle, used to connect and tighten tie rods, and the flanged pipe joint, used to connect pipes. Both are drawn as assembly drawings.

Key ideas

• A turnbuckle has a central body with a right-hand thread at one end and a left-hand thread at the other.
• Turning the body draws the two rods together or pushes them apart, adjusting tension.
• Lock nuts prevent the turnbuckle from loosening.
• A flanged pipe joint uses flanges on the pipe ends, bolted together with a gasket between them.
• Bolt holes in the flanges lie on a pitch circle and are equally spaced.

How to prepare

Understand the working principle of the opposite threads in a turnbuckle and be able to calculate the change in length for a given number of turns. For flanged joints, learn the parts, the role of the gasket and how bolt holes are laid out on the pitch circle.