What are the two types of expansion joints?

The correct answer identifies the two main types of expansion joints as corrugated and slip. Expansion joints are essential components in structures and piping systems, designed to accommodate movement caused by thermal expansion, contraction, or vibration.

Corrugated expansion joints are designed with a series of folds or waves, which allows for flexibility and movement. They are effective in absorbing energy and accommodating various levels of motion, making them suitable for applications requiring a significant degree of flexibility.

Slip expansion joints operate on the principle of one part sliding over another, enabling the joint to adjust to changes in length due to temperature variations. This type of joint is often employed in systems where the movement is expected to be limited in terms of the amount of expansion or contraction.

The other choices, while mentioning valid types of joints, do not accurately capture the common terminology used to categorize expansion joints in engineering contexts. Flexible and rigid refer more broadly to the overall nature of materials used rather than specific types of expansion joints. Standard and custom highlight the manufacturing processes rather than types related to their operational function. Fixed and moveable indicate the mobility characteristics but do not clearly classify the structural design of expansion joints. Hence, corrugated and slip specifically denote recognized categories within the scope of expansion joints.