- Home
- Steam Resources
- Steam Theory
- Insulating Traps
Steam Trap Considerations
Insulating Traps
Steam transport piping is insulated to prevent steam losses due to radiant heat. It is also important to insulate valves and pressure reducing valves having large radiant heat surface areas that are connected to this piping. What about steam traps?
Steam is supplied to the inlet of a steam trap, so the inlet piping should also be insulated to prevent radiant heat loss.
But is it OK to insulate all steam traps regardless of the conditions? Actually, no. There are some circumstances in which it is not acceptable. Since there are many different types of traps, whether or not it is OK to insulate the trap depends on its type.
Traps that can be insulated without adverse effects
Float type
Because the valve opens and closes based only on the change in water level inside the trap, insulating the trap has no adverse effects whatsoever.
Traps that should only have light insulation
Bucket type
The buoyancy of the bucket is used to open and close the valve, but because this occurs in conjunction with steam condensation inside the trap, heavy insulation may result in impaired operation.
Traps that should not be insulated
Disc type and thermostatic type
With these types of traps, the trap must cool down for the valve to open (‘the cooling of the trap’ is a necessary condition for the valve opening movement). If the trap is insulated, it is difficult for the trap to cool down, and the opening of the valve is delayed. This delay in valve opening causes condensate to accumulate instead of being discharged, so these types of traps must not be insulated.
To insulate, or not to insulate
As we can see from the breakdown of traps into these categories, only float type traps can be insulated regardless of the conditions. Care must be taken with all other types of traps, as over-insulating may lead to condensate pooling.
At the same time, care must also be taken that traps in the ‘should not be insulated’ group do not get too cold, as this results in the danger of the valve opening even in the absence of condensate, thus leading to large steam losses.
At the time of the oil crises in the 1970s, there was talk in Japan of huge energy savings to be gained by placing an empty can over steam traps, and actually this idea provided a brilliant balance between not insulating at all and over-insulating. In fact, most modern-day disc traps come equipped with a cap that is similar to this empty can.
As we have seen, traps should only be insulated after thorough consideration of their characteristics.
