The tracer in a steam tracing system must be as flexible
as possible for ease of installation and conformance
to the shape and layout of the process pipes and
equipment being heated and must act as a leakproof
carrier of the heating media. Whenever possible it is
recommended that semi-rigid tubing be used rather
than rigid pipe for tracing because considerably less
force is exerted as a result of differential expansion
between the tracing element and the process pipe or
equipment. Therefore, the tracer can be held closer to
the surface of the heated pipe or equipment to provide
a higher heat transfer rate. Additionally, tubing systems
can be installed in about half the time required for a
piping system when long length coils are used due to
the elimination of the many welded joints required to
make up a rigid carbon steel pipe tracer for a complex
process piping system. A semi-rigid tube tracing system
will require a minimum number of joints, which can be
made up by using compression fittings.
Steam tracers shall be selected to fulfill the thermal
and installation requirements. These requirements are
determined by the process pipe material, temperature
of the process pipe and tracer, pressure of the heating
media as well as the environment in which the tracer
will operate. The tracer shall be a metal close to the
potential of the process pipe so as to minimize galvanic
corrosion. Recommendations are as follows:
a) Copper tubing tracers shall be soft annealed grade
122 and meet ASTM Standard Specifications B68, B75,
B88, B251 and B280. Minimum wall thickness shall be
as follows:
3/8” O.D. x 0.032” wall (10mm O.D. x 1 mm wall)
1/2” O.D. x 0.035” wall (12mm O.D. x 1 mm wall)
3/4” O.D. x 0.049” wall (20mm O.D. x 1.2 mm wall)
b) Copper tubing shall be used if the saturated steam
pressure or the item being traced does not exceed 400F
(204C) and there is no corrosion or other deterrent for
using copper.
c) Stainless steel tubing tracers shall be type 316 seamless
cold drawn and fully annealed with a maximum
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Rockwell hardness of RB90 and meet ASTM Standard
Specifications A269, A213, A249 and, A450. Minimum
wall thickness shall be as follows:
3/8” O.D. x 0.032” wall (10mm O.D. x 1 mm wall)
1/2” O.D. x 0.035” wall (12mm O.D. x 1 mm wall)
3/4” O.D. x 0.049” wall (20mm O.D. x 1.2 mm wall)
d) Stainless steel tubing shall be used if the saturated
steam pressure or the item being traced has a maximum
temperature above 400F (204C) and there is no corrosion
or other deterrent for using stainless steel.
e) Carbon steel cylindrical tracers are not recommended
for steam tracing circuits. During shutdown
periods, the combination of air and moisture on or in
the tracers causes rapid rusting.
f) Since the tracer tube is a primary component of the
steam tracing system, the tubing shall be thoroughly
inspected prior to use to see that it conforms to the
specification, is of the correct diameter and thickness
and is not out of round.
The pressure design and temperature ratings are of
utmost importance in a tracing system. ANSI/ASME
B31.3 Code addresses these requirements for process
piping by including ASTM Standard Specifications that
must be met under the Code.
The Table below provides information on the allowable
pressure rating (psi) for typical tubing tracers used at
temperatures up to 400F (204C). Stainless steel tubing
tracers may be used at temperatures much higher than
those shown in the table.
• Calculations Based On ANSI/ASME B31.3 Code.
• No Allowance Made For Corrosion Or Erosion
• Calculations Based On Minimum Wall And Maximum
O.D. Allowable Under ASTM A269 Specifications For
Stainless Steel Tubing
• Calculations Based On Minimum Wall And Maximum
O.D. Allowable Under ASTM B75 Specifications For
Copper
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