Page 199 - Root Cause Failure Analysis

STEAM TRAPS

Steam-supply systems commonly are used in industrial facilities as a general heat
source as well aq a heat source in pipe and vessel tracing lines used to prevent freeze-
up in nonflow situations. Inherent with the use of steam is the problem of condensa-
tion and the accumulation of noncondensable gases in the system.

Steam traps must be used to automatically purge condensable and noncondensable
gases, such as air, from the steam system. However, a steam trap should never dis-
charge live steam. Such discharges are dangerous as well as costly.

CONFIGURATION
Five major types of steam traps commonly are used in industrial applications:
inverted bucket, float and thermostatic, thermodynamic, bimetallic, and thermostatic.
Each type of steam trap uses a different method to determine when and how to purge
the system. As a result, each has a different configuration.

Inverted Bucket
The inverted-bucket trap, shown in Figure 15-1, is a mechanically actuated steam trap
that uses an upside down, or inverted, bucket as a float. The bucket is connected to the
outlet valve through a mechanical link. The bucket sinks when condensate fills the
steam trap, which opens the outlet valve and drains the bucket. It floats when steam
enters the trap and closes the valve.

As a group, inverted-bucket traps can handle a wide range of steam pressures and con-
densate capacities. They are an economical solution for low- to medium-pressure and
medium-capacity applications, such as plant heating and light processes. When used

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