Hose Clamp: the tighter, the riskier?
Myth has it that the tighter we fasten a hose clamps, the better. When in fact, overtightening can ruin both rubber hose and clamp, not to mention higher chance of leakage. Therefore, for safety factor of hose and clamp, most OEM parts would have constants (Nm) for clamp fastening. These constants vary according to size and usage.
A user once contacted us with the problem of leakage when connecting plastic pipe to rubber hose. After an investigation, we found out that clamps was overtightened, causing the plastic pipe to misshape. In that case, the user had to change the whole unit, resulting in unnecessary extra cost.
Normally, the relation of torque and tightness is in direct variation, meaning the more we screw the clamp, the tighter it becomes. However, at some point this relation between the input (torque) and output (tightness) stops being in direct variation. The excess torque would then result in the damage of clamp, hose, or pipe instead, as overtightening violates the safety factor of clamps.
When installing clamps, torque meter is usually needed to make sure the torque matches the guideline given for each clamp. Nevertheless, the following technique is applicable in the lack of torque meter. It is to screw clamps just until hose is slightly sink to the same level as clamps. Stop screwing when the surface is smooth. Do NOT overtighten!