What are the fire-resistant advantages of PVC threaded penetration pipes compared to metal wall sleeves?
Publish Time: 2025-11-05
In building electrical and piping systems, wall sleeves are crucial components ensuring the safe passage of cables and pipes through walls or floors. Facing the significant safety hazard of fire, the fire resistance of the sleeve directly affects whether fire will spread rapidly and whether toxic fumes will diffuse through openings. Traditionally, metal wall sleeves have been widely used due to their non-combustible nature; however, with advancements in materials technology, PVC threaded penetration pipes have demonstrated unique fire-resistant advantages in specific applications. The difference in fire resistance is not a simple matter of "one is better than the other," but rather each has its strengths in different dimensions. A thorough comparison helps in making more scientific and safer choices in engineering practice.1. Combustion Characteristics: Non-combustible vs. Flame-retardant – Fundamental DifferencesMetal sleeves are non-combustible materials; they do not burn, release heat, or contribute to the fire in a fire—this is their core fire-resistant advantage. Ordinary PVC material, on the other hand, is a combustible organic polymer that softens, burns, and releases heat when exposed to an open flame. Modern PVC threaded penetration pipes used in construction are mostly made of flame-retardant modified PVC. This means they are rapidly self-extinguishing after the fire source is removed, with extremely low flame propagation speed, and release far less heat and smoke than ordinary plastics during combustion. Therefore, while high-quality flame-retardant PVC threaded pipes are not "non-combustible," they possess the characteristics of being "flame-retardant, self-extinguishing, and having low heat release," effectively delaying the spread of fire through openings in the early stages of a short-term fire.2. Fireproof Sealing Synergy: Sealing Determines Overall Fireproof PerformanceThe fireproof effect of wall sleeves depends not only on the pipe material itself, but more importantly on whether the gap between it and the wall is effectively sealed. Metal sleeves, due to their smooth surface and low coefficient of thermal expansion, have poor adhesion to fireproof sealant or fireproof putty, and are prone to micro-gaps due to metal expansion at high temperatures, leading to smoke leakage. PVC threaded penetration pipes, on the other hand, have a threaded structure on their surface, which not only enhances the mechanical interlocking force with the wall, but their rough surface also facilitates the adhesion and filling of fireproof sealing materials. More importantly, PVC's coefficient of thermal expansion is closer to that of concrete, resulting in better deformation coordination during fire heating, which helps maintain the integrity of the sealing system. This synergistic sealing performance of the "pipe-wall-seal" three-in-one system makes PVC threaded pipes more reliable in actual fireproof sealing systems.3. Smoke and Toxic Control: The Environmental Advantages of Halogen-Free Flame-Retardant PVCThe primary cause of death in fires is not the flame itself, but the toxic smoke. Ordinary PVC releases corrosive and toxic gases such as hydrogen chloride when burning. However, halogen-free, low-smoke, flame-retardant PVC threaded pipes, by using inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide, do not produce halogen gases during combustion, resulting in low smoke density and low toxicity, significantly improving the safety of personnel evacuation. In contrast, although metal conduits do not produce smoke, if the internal cables are insulated with ordinary PVC, they will still release a large amount of toxic smoke at high temperatures. Therefore, in terms of overall smoke and toxicity control, the combination of halogen-free flame-retardant PVC threaded pipes and halogen-free cables may actually be superior to the solution of metal conduits and ordinary cables.4. Applicable Scenarios: Appropriate Selection According to StandardsFor critical fire-resistant partitions such as firewalls and floors, Class A non-combustible materials must be used in conjunction with fire-stopping systems. In these cases, metal sleeves remain the preferred choice. However, in non-critical partitions, equipment rooms, ceilings, or temporary wall penetrations, using flame-retardant PVC threaded penetration pipes in conjunction with a professional fire-stopping system can fully meet local fire protection requirements, while also offering advantages such as convenient construction, low cost, good insulation, and corrosion resistance.While PVC threaded penetration pipes do not completely surpass metal sleeves in fire resistance, their self-extinguishing properties after flame-retardant modification, excellent synergy with fire-stopping materials, and the low-smoke and low-toxicity characteristics of halogen-free models give them unique value in specific application scenarios. True fire safety lies not in the "absolute non-combustibility" of a single material, but in the integrity and reliability of the entire wall penetration system. Scientific material selection, standardized construction, and rigorous sealing are the fundamental ways to protect the "fire safety lifeline" of buildings.
