ssistance for an impedance heating system to heat gasses or fluids flowing through your
pipeline. It can also be used over a wide range of temperatures to prevent freezing in cold
weather, maintain fluidity of viscous materials, raise the temperature of heat sensitive materials
or maintain gas temperatures up to 1600
o
F.
The Hynes Electric Heating Company designed and fabricated electric heating equipment for
demanding industrial applications since 1926. Based upon field experience with thousands
of successful world-wide installations, Hynes was a recognized leader in electric process and
pipeline heating applications for temperature sensitive liquids and gases.
In 1987, INDEECO purchased the Hynes Electric Heating Company. Together, INDEECO
and Hynes represent many years of experience in electric process heating. We look forward
to putting that experience to work for you in your next impedance heating application.
Introduction
Benefits and Advantages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
How Impedance Heating Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Customers and Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Impedance Heating Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
Engineering Application Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-9
The Impedance Heating System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-11
Application Data Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Limited Warranty

Benefits of Impedance Heating
Benefits and Advantages
1
Low Voltage Operation
All systems operate
at less than 30 Volts, many at 10 Volts or below.
INDEECO systems meet or exceed the requirements
of the National Electrical Code (Article 427), assuring
safe operation.
Uniform Heating
Because the entire pipe
effectively acts as the heating element, heat
is generated uniformly throughout its entire
length and circumference without hot spots.
Simplicity
The impedance method takes the
complexity out of pipeline heating. A few basic
components comprise the entire heating system.
Installation is simple; it can be installed without
disturbing most of the existing thermal insulation.
Wide Temperature Range
INDEECO has
pioneered the use of impedance heating for
applications ranging from below freezing to
1600
o
F. It is often the only viable option for high
temperature pipeline heating.
Close Control
Thermocouple sensors placed
along the pipeline provide precise, uniform
temperature control. Optional SCR controls give
the ability to achieve control within ± 1
o
F.
Low Cost
Installation costs are kept to a
minimum by the inherent simplicity of the system.
Likewise, maintenance is virtually eliminated; many
systems operate unattended. Energy costs are low
because the required energy is concentrated in the
pipe and efficiently heats the fluid or gas traveling
through it.
No Burnouts
When the pipe becomes the
heating element, burnouts and failures associated
with electrical resistance tapes and cables are
eliminated.
No External Fluids
Pipeline heating with
steam or high temperature fluids introduces a
high degree of complexity and a potential hazard.
Impedance heating accomplishes the same result
in a simple, straightforward manner.
No Leaky Jackets
With impedance heating,
you wont have leaky steam lines, cracked steam
traps, pump failures or frozen return pipes.
No Hot Spots
Impedance heating eliminates
the danger of overheating temperature-sensitive
materials (asphalt, chocolate, heavy syrups) because
hot spots associated with conventional pipe tracing
are eliminated.
No Routine Maintenance
Routine
maintenance is eliminated, along with the
replacement parts and production shutdowns
associated with such maintenance.
Advantages Over
Conventional Methods 2
How Impedance Heating Works
The basic concept of impedance heating is quite
simple: Terminals are attached to each end of
the pipe, and a low voltage current is passed
through it. In other words, the pipe acts as its
own heating element.
The explanation of how impedance heating works
is a bit more complex. Traditionally, electric heat is
generated by passing current through a wire that is
purely resistive. This is how electrical resistance tape
or cable tracing produces heat. With the impedance
method, heat is generated by combining three
different effects:
1. The pipe acts as a resistor, much the same as
a wire in the traditional method. The electrical
resistance of the pipe depends upon its length,
composition and wall thickness.
2. When heating a straight length of pipe, it
is necessary to attach a power cable to one
end (see Figure 1). The cable is normally laid
on the pipe s insulation jacket. The current
flow in a typical impedance system is enough
to set up a significant magnetic field around
the cable. Since most pipes are made from
magnetic materials, steel being the most
common, the magnetic field interacts with
the pipe, producing the second component
of heat, skin effect/proximity effect.
3. A 60 hertz power source produces a magnetic
field that changes direction 60 times per
second. The electrical inertia of the pipe
relative to these changes produces a
hysteresis effect, which is the third source
of heat in the impedance method.
Taking all of these effects into account, INDEECO
designs and furnishes a hardware package to gener-
ate the proper amount of heat for a given pipeline
system. That package consists of the following: Power Transformer
A transformer, fed from
a commercial power source, produces the correct
voltage to give adequate heat and safe operating
conditions. Furnished in its own enclosure, the
transformer has multiple taps to fine-tune the
voltage output in the field. Output voltages range
from 1 to 30 Volts.
Control Panel
Pipe temperature is controlled
by a thermocouple sensor attached to the pipe.
The standard control panel includes a process
temperature controller, magnetic contactor and
all necessary pilot lights, relays, fuses, etc.
Optional solid-state proportional control, with
fully modulated SCR, is also available for more
precise temperature control.
Terminal Plates with Cable Lugs
Terminal
plates are supplied for field attachment to the
pipe and low voltage power cabling. Flange Isolation Kits
In order to confine
the electrical current to the section of pipe
being heated, INDEECO can furnish isolation
kits consisting of an isolator gasket for each end
of the pipe and isolator bolts with proper washers
to secure the gasket and mating flanges. Note
that standard field-furnished flanges are used
with the isolation kits. No special flange treatment
is necessary.
Power
Cable
Thermocouple
Leads (attach
to control panel)
Control Panel
NEMA 3R
Transformer
Cable Lug
INLET
Thermocouple
Connection
Terminal
Plate
Flanges
Isolator Bolt
Steel Washer
Isolator Washer
Isolator Gasket
Standard
Pipeline
Insulation
Jacket
Strap
Figure 1 Impedance systems heat a wide variety of gases,
liquids and viscous materials which are stored,
pumped and processed in many different
industries and applications. Impedance heating
can be used in three basic ways:
Cold Start:
Heat is applied to increase fluidity of
static, viscous materials so they can be pumped.
Typical materials include asphalt, molasses and
heavy fuel oils.
Maintain Temperature or Pipe Tracing:
Heat
is applied to a liquid or gas flowing through a pipe
to offset heat losses. Typical applications include
freeze protection or maintaining the fluidity of
viscous materials.
Temperature Rise:
Heat is applied to a liquid or
gas flowing through a pipe in order to raise its
temperature between the inlet and outlet of the
heated pipe. Typical applications include heating
corrosive liquids or high temperature process air.
Customers and Applications
A partial list of customers and applications are shown below.
CUSTOMER
MATERIAL HEATED
TEMP (
o
F)
PIPE LENGTH (FT)
Allied Chemical Corp.
Coal Tar Pitch
450
131
Allied Fibers Corp.
Superheated Steam
1040
70
Aluminum Co. of America
Pitch
170
1155
American Hoechst Corp.
Polypropylene
400
22
Amoco Oil Co.
Fuel Oil
280
891
Amoco Oil Co.
Zinc Chloride
700
53
Arco Oil & Gas Co.
Crude Oil
150
15700
Atlantic Richfield
Salt Water
40
802
Barnard & Burk
Sulphur
265
70
Bethlehem Steel
#6 Fuel Oil
280
891
Bouligny Co.
Superheated Steam
845
34
British Petroleum Alaska
Water
40
611
Brown & Root Inc.
Crude Oil
50
1270
Catalytic Corp.
Liquid Pentasulfide
752
2
Celotex Corp.
Asphalt
400
1760
Certain Teed Corp.
Asphalt
480
52
Chemtex Inc.
Polymer
536
52
Chevrolet Motor Div.
Catalyst
70
770
Colgate Palmolive Inc.
Sulphur
300
165
E.I. Dupont
Process Gas
575
170
Emery Industries
Stearic Acid
160
370
Ethyl Corp.
Powdered Catalyst
450
53
Exxon Research & Engineering
Heavy Fuel Oil
950
552
Exxon Synthetics Inc.
Coal Slurry
370
558
Fisher Scientific Co.
Resin & Hardener Mix
194
40
Fortifiber Corp.
Asphalt
500
250
Foster Wheeler Corp.
Paraffin
60
1020
H.K. Ferguson
Pitch
735
100
Hershey Foods Corp.
Chocolate
110
377
Honeywell
Air
1200
114
Inland Steel Co.
Fuel Oil
160
8500
Intalco Aluminum
Air/Tar Mixture
500
52
International Paper
Wax
185
520
Kaiser Aluminum Co.
Coal Pitch
380
500
Kitchens of Sara Lee