How long do Plastic castable typically last before needing to be replaced?

The lifespan of plastic castables can vary depending on the application and operating conditions, but in general:

For low to moderate temperature applications under 1200°F/650°C, plastic castables should last 5-10 years before needing replacement.

At maximum continuous use temperatures of 1200-1400°F/650-760°C, lifespan is typically 3-5 years.

In intermittent or cyclic high heat applications reaching 1400-1600°F/760-870°C, lifespan may only be 1-3 years.

Above 1600°F/870°C, plastic castables are not recommended for continuous use and longevity would be under 1 year.

Factors that can reduce lifespan include:

Higher operating temperatures
Thermal cycling and rapid heating/cooling
Severe chemical or molten metal contact
Mechanical vibration or erosion
Improper installation techniques
Incomplete repair of cracks or damage
Lack of refractory back-up or substrate support

Proper fabrication and installation, as well as preventative maintenance like re-plastering cracks, can help plastic castables achieve their maximum lifespan even under demanding conditions. But eventual replacement is typical after a number of years of high heat exposure.