Dry fiberglass (FRP) oil-oil casing pipes perform excellently in wastewater treatment scenarios, but must match the working conditions. The core advantage is corrosion resistance, while the main limitations are temperature resistance, pressure resistance, and resistance to mechanical damage. Here is a detailed analysis:

1.Core Advantages (Outstanding Performance in Sewage Treatment)

It has very strong corrosion resistance and a lifespan far longer than metal pipes

FRP is a resin matrix (epoxy, vinyl, phenolic acid, etc.) and glass fiber, and is almost inactive against acids, alkalis, salts, microorganisms, and dissolved corrosive media in wastewater. It is especially suitable for high salt, high sulfur, high acidity and alkalis, and corrosive organic materials

industrial/municipal wastewater.

Ordinary carbon steel will perforate in corrosive wastewater after only 2~5 years, and 304 stainless steel may also experience pitting; Under conventional sewage conditions, fiberglass bushings can last 20~30 years, significantly reducing operation and maintenance costs.

Lightweight, easy to install and maintain

Its density is only 1/4~1/5 that of carbon steel, so transportation, hoisting, and installation do not require large equipment. It is especially suitable for underground utility tunnels, narrow spaces, and expansion projects, improving construction efficiency by over 30%.

The inner walls are smooth, making them resistant to scaling and clogging

The inner wall roughness is only 0.0084~0.01mm (about 0.045mm for steel pipes), low resistance to sewage flow, and less likely to adhere to sludge, algae, or biofilm. Long-term flow rate decays slowly, and dredging frequency is low.

Low maintenance costs and no electrochemical corrosion

No anti-corrosion coating is needed, there is no risk of electrochemical corrosion from metal pipes, and daily inspections only require interface and appearance, resulting in minimal operation and maintenance workload.

2.Key Limitations (Operating Conditions to Avoid)

Its temperature resistance range is limited; it is not suitable for high-temperature wastewater

Conventional resin-based fiberglass can be used at ≤80°C for long-term use (epoxy about 60~80°C, vinyl about 90°C). Above this temperature, the resin softens and degrades, causing a sharp drop in strength. If the wastewater temperature > 90°C for a long time, special high-temperature resistant resins (such as phenolic acid) should be selectedEpoxy), with costs rising significantly.

Its pressure-bearing capacity is weaker than that of metal tubes, limiting high-pressure scenarios

Although the circumferential tensile strength of dry-type FRP bushings is high, their axial strength is low and brittleness is high. Long-term pressure control requires pressure control:

Conventional products have a pressure ≤ 1.6MPa, while high-pressure sewage (>2.5MPa) requires special design, greatly increasing costs and construction difficulty.

If the sewage system experiences frequent pressure fluctuations and water hammer impact, it can easily lead to casing delamination and cracking.

High sealing requirements for the interface

sockets, flanges, or threaded connections are often used. If the sealing is inadequate during installation, sewage can easily seep between sleeve layers, leading to layering failure; Moreover, fiberglass cannot be welded, and repairs require appropriate adhesives, making on-site repairs difficult.

3.Summary

Dry-type FRP oil-oil sheath pipes perform well in medium-low temperature, medium-low pressure, and highly corrosive wastewater treatment scenarios, making them an optimal alternative to metal pipes; However, under high temperature, high pressure, and strong mechanical impact conditions, careful selection is necessary, and metal pipes or special materials may be used if necessary

Composite materials. In practical application, targeted design and protection must be made based on the composition of the wastewater, temperature, pressure, and construction conditions.