There are different types of steam trap
used in the upstream and downstream
industry. Depending on the suitability of
the process, these different types of traps
are employed. Typical examples are as
follows; together. When cold the bimetallic strip
is flat, allowing the valve to open. When
steam enters the chamber, the strip is
heated and takes an oval shape, causing
the valve to close. It is always used in
constant steam main and tracing lines.
• Inverted bucket trap • Impulse steam trap • Balanced pressure thermostatic trap • Float actuated trap • Bimetallic trap INVERTED BUCKET TRAP: Several
principles is employed in the operation
of this trap. The water and steam enters
at the bottom and flow upward into the
inverted bucket. As long as the bucket
contains steam, it is buoyed up in same
way that an inverted empty bucket is
buoyed up in water. While in this position,
the valve is closed and there is no
discharge of water or steam from the trap.
As water enters the bucket it displaces the
steam and the bucket looses its buoyancy
and drops, causing the valve to open.
After the water has been discharged,
the bucket again fills with steam, the
buoyancy is restored and the valve closes.
A small vent at the top of the bucket
allows air to escape, thus preventing it
from interfering with trap position.
BIMETALLIC TRAP: Like in Port Harcourt
Refining Company Ltd, Nigeria, the
most commonly used steam trap is the
bimetallic trap. This trap is small and
lightweight and provides maximum
discharge of non-condensables. It can
withstand freezing, water hammer, high
pressure and super-heated steam. It
discharges condensate well below steam
temperature to reduce flash steam.
The bimetallic trap consists of a strip
of two dissimilar metals with different
coefficient heat of expansion joined
THERMOSTATIC TRAP: The release of air is
controlled by a thermostatic vent which
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