Heat Transfer Information
American Society of
Mechanical Engineers. The ASME Boiler and
Pressure Vessel Code is a recognized and
accepted standard throughout the world for the
constructs of pressure vessels. The rules are
formulated to provide minimum requirements for
safety and serviceability and at the same time
provide for reasonable and realistic costs.
At ITT Standard either
20%, 35%, or 45% of free area or percent of area
cut off of the whole diameter baffle plate.
Also called support
plate. A plate in which the tubes pass through
for support. Also provides a blocked path for
the shellside medium. This blocked path forces
the shellside medium across the tubes providing
better heat exchanger performance.
The space in-between the baffle plates on a tube bundle. Baffle spacing
is adjusted to achieve maximum heat exchanger performance.
The circular dimension
line on which bolt holes are drilled.
The name of a tube sheet
exchanger part. It directs the tubeside medium
for distribution through the tubes. It may also
contain the tubeside inlet and outlet
connections and/or pass ribs. It differs from a
channel in the sense that it does not have a removable cover. See Channel Assembly and
The name of the tubing
assembly in removable bundle heat exchangers. It
usually consist of tubes, tubesheets, baffles,
spacers, and tierods. See Core Assembly.
The threaded bolt used to hold the bonnet onto the core of BCF type heat exchangers. ITT Standard uses hex head capscrews but many different head types are available. Capscrews always have a head on one end with threads at the other.
See Bonnet Assembly and Waterbox. Performs same function as bonnet assembly. However, a removable cover permits access to the ends of the tubes. Also the name of a structural construction product which is shaped like the letter "C".
The name of the shell assembly and tube assembly in fixed tubesheet heat exchangers.
The name of a part which is used to connect customers's piping to our heat exchangers. At ITT Standard these couplings rarely exceed 3" sizes. Couplings come in many styles. The most used style at ITT Standard being the half couplings which we use for vent and drain pipe tap connections.
The name of the part
which is used to cover an opening on a heat
exchanger. Channel covers are used in
conjunction with channels to seal off the
tubeside of the heat exchanger. Nozzle covers
can be used to cover nozzle openings to keep
heat exchanger internals clean during shipping
and storage. Covers are different from end
plates in the sense that they can be removed
from the heat exchanger to clean the interior of
the tubeside, without disturbing any piping.
The name of the part used
to support the entire heat exchanger. Cradles
may be fixed or moveable. Is also used to secure
the heat exchanger to the customer's mounting
surface, when they are welded or strapped to the
The pressure used by
engineers to calculate part thickness and heat
exchanger design. It is generally slightly
higher than the most severe condition or highest
operating pressures seen by the heat exchanger.
Also called Maximum Allowable Operating
The name of a type of
nozzle connection. A dome provides a larger
nozzle opening between the customer's pipe size
and heat exchanger tube bundle, usually to
prevent tube erosion due to high inlet
End plates are covers
which have been welded to the heat exchanger.
Most end plates are used on bonnet assemblies.
The first baffle space on
a tube bundle. It is the space between the
tubesheet and the first baffle plate. The end
zone is adjusted to keep the baffle plates
within the two shell side nozzles.
A small piece of tubing
approximately 1 inch long made of copper or
stainless steel. The ferrule is crimped or
squeezed onto the tie tube, up against the last
baffle, thus locking all the baffles into
tubesheet. The tubesheet on a core assembly.
Any tubesheet that is an integral part of the
The tubesheet at one end
of a removable tube bundle. The floating
tubesheet will always have a smaller diameter
than the stationary. The floating tubesheet is
allowed to move freely with the expansion and
contraction of the tube bundle due to
temperature changes in operation.
A sealing device used in
between two parts to prevent leakage. Types
include inside the bolt circle, (no bolt holes)
& full face, (has bolt holes, is as large as
The cast or forged part
of a BCF/SSCF core assembly. The hub is made up
of a tubesheet, shellside nozzle connection and
vent/drain connections. The hub eliminates
additional welding or brazing operations,
therefore, making the exchanger less expensive.
A small perforated plate
or bar assembly placed inside of the shellside
nozzle, usually a dome type nozzle. They can
also be attached directly to the bundle by being
tack welded to the tierods. The impingement
plate protects and prolongs the life of the tubes.
The impingement plate breaks up and slows down
the shellside fluid, which otherwise would erode
In and Out End
The end of the heat
exchanger which contains the tubeside inlet and
outlet connections in a multi-pass unit.
A nylon or metal ring on
some packed joint heat exchangers. The lantern
ring fits over the outside diameter of the
floating tubesheet between the packing rings.
When the joint is tightened it holds the packing
rings in place. The Lantern Ring also has small
holes which act as leak detectors. The leak
detectors let the customer know if one of the
fluids is leaking around the packing rings. The
fluids never mix.
Lap Joint Flange
Also called Van Stone.
These flanges are used to reduce the amount of
an expensive material (S/S) required to make a
flange. A steel ring is used in tandem with the
more exotic material. The exotic material will
be at the fluid contact surfaces or where the
fluid touches the flanges. The steel ring
contains the bolt holes. These flanges are also
used on stainless steel C-200 type heat
exchangers for tubesheets.
A short piece of pipe
threaded on both ends.
The pressure a heat
exchanger is actually operating at while in use.
Outer Tube Limit
The O.T.L. is the
diameter created by encircling the outer most
tubes in a tube layout. The design O.T.L. is
used by engineers to calculate clearances
between bundle parts. The actual O.T.L. is
usually a few thousandths less than the design O.T.L.
The end of a heat
exchanger which contains the packed joint. This
packed joint contains the packing rings. It is
also called the floating end of the unit, where
the floating tubesheet is located.
A fairly soft
non-metallic ring which is used to seal the
floating tubesheet or packed end of the heat
exchanger. The packing ring slips over the
floating tubesheet on either side of the lantern
ring. It also fits into a groove in the shell
and bonnet flange, or is held in place by
retaining ring assembly.
A lane in a tube layout
where there are no tubes. The pass lane is the
surface on the tubesheets where the pass ribs
A separator plate inside
a bonnet or channel. This rib mates with the
pass lane surface. It is used to create
multi-pass heat exchangers. By arranging the
ribs, a designer can control the flow of the
Also called a zinc. A
sacrificial anode usually placed in the tubeside
of a heat exchanger. The zinc protects the
tubes, tubesheets and bonnets against corrosion.
When water is flowing through the tubeside the
zinc is consumed instead of the other heat
A quadrant type tube
layout. Four separate quarters of a tube layout
with pass lanes between them. The type of tube
layout used on all BCF's except the 8" size.
A type of heat exchanger
in which the tube bundle can be removed from the
shell pipe. The removable bundle provides easy
cleaning of the shellside and also a less
expensive way of replacing worn out tubes.
Retaining Ring Assembly
A metal assembly used on
ACA, GC and/or OC packed joint heat exchangers.
The retaining ring assembly performs the same
job as a lantern ring. The retaining ring
assembly eliminates the need for a stuffing box
flange. See Lantern Ring.
The end of a heat
exchanger where the tubeside fluid reverses its
flow in a multi-pass unit. It usually contains
only small vent and drain connections.
A type of tube layout or
pass rib pattern. It is used on our 8 inch BCF's and
is so named because it creates an end to end
flow which looks like a piece of ribbon candy.
The final assembly
drawing of an ITT Standard heat exchanger. This
drawing will always have a part number that
starts with the number 5.
The name of the assembly
into which the tube bundle fits. The shell also
contains the shellside connections.
A shell head is a formed
plate which is welded to the shell (or bonnet)
pipe. The shell head can be many styles or
shapes, including flanged and dished,
elliptical, ellipsoidal, and hemispherical.
Generally, as a head gets flatter it gets
weaker, therefore designers can use a flat end
plate or a thinner formed head to do the same
The side of a heat
exchanger where the fluid circulates around the outside
of the tubes. See Tubeside.
A type of nozzle flange.
A slip-on flange slips over the nozzle pipe and
is welded in place.
A piece of tubing that
slides over the tie rod or tie tube between the
baffle plates. The spacer holds the baffle plate
in a permanent position.
Two or more heat
exchangers which have been stacked together
either side by side or one on top of the other.
These units have interconnecting piping hooking
The tubesheet at one end
of a removable bundle. It has a larger diameter
than the floating tubesheet. The stationary
tubesheet is held together in a permanent
position between the bonnet and shell flanges.
A stub end is the fluid
contact surface used with a lap-joint flange. At
ITT Standard it is usually made of stainless
steel but it can be other materials.
A stud bolt is used to
hold two or more pieces together. It is threaded
the full length (T.F.L.) and fits through bolt
holes which are not tapped. A hex nut is used on
both ends. A stud is similar to studbolt except
it threads into a tapped hole and a hex nut is
used on one end only.
Stuffing Box Flange
A flange used at a packed
end joint. When a packed joint is tightened the
packing ring is forced into this flange by the
lantern ring or lantern gland.
See Cradle Assembly. A
support foot is usually bolted to the heat
exchanger using the bonnet to shell flange
Tubular Exchange Manufacturer's Association. The TEMA Standards
cover the design, manufacture, installation,
operation, and maintenance of shell and tube
heat exchangers. TEMA C is for generally
moderate requirements of commercial and general
process requirements. TEMA B is for chemical
process services. TEMA R generally serves
requirements of petroleum and related processing
Generally 1.5 times the
design pressure. The pressure used during a
hydrostatic test. The test is made to detect
leaks at any joint on the heat exchanger.
A small diameter rod
which threads into the stationary end tubesheet.
This rod ties the baffles and spacers together.
A tie tube takes the
place of the tie rod in a small diameter heat
exchanger. It serves the same purpose as a tie
The tube layout drawing
shows the positioning of the tubes inside the
heat exchanger. It also shows the locations of
The tubesheet is a plate
that secures both ends of the tube in a heat
exchanger. Both the shellside and tubeside
mediums come in contact with it.
The side of a heat
exchanger where the fluid circulates through the
inside of the tubes. See Shell Side.
See Bonnet Assembly and
Channel Assembly. Another name for bonnet or
Weld Neck Flange
A type of nozzle flange.
A weld neck flange is used when a butt weld is
required. This means the end of the flange butts
up against a piece of pipe, both the flange and
the pipe are bevelled. The joint provides sound
weld with no overlapping of parts.
The number of times the
fluid passed through the tube bundle. In a one
pass unit the tube side medium passes through
all the tubes once. In a two pass unit it passes
through one half of the tubes and returns
through the other half. A four pass unit goes
through approximately one quarter of the tubes,
down and back four times. Greater than 1 Pass is
referred to as a multi-pass unit.