What is the effect of maintaining tension in tubing under hydraulic pressurization?

• A. Tension is undesirable because it can cause expansion and shift
• B. Tension improves stability
• C. Tension reduces required bend radii
• D. It has no effect

Answer: (A)

When tubing is pressurized, the fluid inside pushes outward on the walls, causing the tube to try to lengthen a bit and to expand. If the tube is already under tension, that additional axial loading makes the tube tend to elongate more, which can cause it to shift or move at supports and fittings. This movement can lead to misalignment, stress at joints, or fatigue over time. So maintaining tension under hydraulic pressurization is undesirable because it increases the tendency for expansion and shifting. Bend radii and other fit considerations aren’t helped by pre-tension, and the effect is real, not none.