Excessive stress on fluid or pneumatic metal tubing caused by expansion and contraction due to temperature changes can best be avoided by ________.

Providing bends in the tubing is a highly effective method for minimizing the excessive stress that can occur due to thermal expansion and contraction. When metal tubing heats up, it expands, and when it cools down, it contracts. Introducing bends in the tubing allows for some flexibility, accommodating these changes in length without putting undue stress on the material or the joints. This design feature creates a more forgiving structure that can handle the dynamic movement created by temperature variations.

Using thicker tubing may offer some increased resistance to deformation, but it does not address the issue of accommodating expansion and contraction effectively. Thicker materials can still experience stresses if they are rigidly fixed in place. Applying lubricants does not mitigate the stresses caused by thermal movement within the tubing itself; lubricants are typically used to reduce friction between moving parts but do not influence the properties of the tubing in terms of expansion. Minimizing joint connections can improve reliability by reducing potential failure points, but it does not provide the necessary flexibility to handle temperature fluctuations. Therefore, integrating bends into the design of fluid or pneumatic metal tubing is the preferred strategy for managing the effects of thermal expansion and contraction.