When selecting insulated pipes, many purchasers rely on a simple intuition: the thicker the insulation layer, the better the thermal insulation performance-so they simply ask the manufacturer to add a few extra centimeters. While this idea sounds logical, in actual engineering practice, excessively increasing insulation thickness not only wastes money but can even backfire, accelerating the failure of the pipeline.
Let's start with the most easily overlooked issue: excessive core temperature. The primary function of an insulation layer is to minimize heat loss; however, it simultaneously prevents the inner working pipe from dissipating heat outward. If the insulation layer is too thick, the steel working pipe remains exposed for prolonged periods to temperatures far exceeding its design limits, thereby accelerating carbonization, creep, and corrosion. This is particularly critical in hot water pipeline networks: when the pipe wall temperature remains elevated for extended periods, the effectiveness of cathodic protection diminishes, and the risk of electrochemical corrosion rises significantly. This is the fundamental reason why certain pipe sections with excessive insulation actually develop leaks sooner than those with standard insulation thickness.
Secondly, the reduction in heat loss is not directly proportional to the insulation thickness. While the thermal resistance of an insulation layer increases in an approximately linear fashion with its thickness, once the thickness reaches a certain threshold, the energy-saving benefits derived from further thickening diminish rapidly. When comparing the material cost of adding an extra centimeter of insulation against the value of the heat energy saved, the cost often exceeds the point of economic equilibrium. In other words, the additional expenditure does not yield a proportional return in energy savings; instead, it occupies a larger volume of underground space or pipe gallery cross-section, thereby complicating both construction and maintenance operations.
A third factor involves the constraints imposed by actual operating conditions. Irregular components-such as valves, elbows, and expansion joints-cannot be uniformly wrapped with thick insulation in the same way that straight pipe sections can. If the insulation on straight sections is made excessively thick, the resulting disparity in insulation thickness between these sections and the "weaker links" (the irregular components) creates distinct "thermal bridges." Heat then dissipates heavily through these junctions, significantly undermining the overall heat-loss reduction that the thickened insulation on the straight sections was intended to achieve.
So, how does one determine the appropriate insulation thickness? The most reliable approach is to perform heat-loss calculations based on specific parameters-including the fluid temperature, pipe diameter, environmental conditions, and projected service life-in strict accordance with relevant design standards (such as GB/T 29047 or CJJ 34). By doing so, one can identify the "economically optimal thickness" that minimizes the total lifecycle cost of the pipeline system. Rather than simply making an arbitrary, spur-of-the-moment demand to "add two centimeters of thickness."