[ Mechanical Engineering ]
S&T Heat Exchanger
BASIC CONSTRUCTION AND TEMA TYPE SELECTION
Copyrightⓒ2009
ⓒ2009
Samsung
Engineering
Co.,
Ltd.
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Samsung
Engineering
Co.,
Ltd.
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rights
reserved
Table of Contents
PART – I
BASIC CONSTRUCTION
What is a Shell and Tube Heat Exchanger
N-2
Nomenclature of Heat Exchanger Components
N-1.2
TEMA Type Designation
RCB-1
TEMA Class Designation
RCB-2
Tubes
RCB-3
Shells and Shell Covers
RCB-4
Baffles and Support Plates
RCB-5
Floating End Construction
RCB-6
Gaskets
RCB-7
Tubesheets
RCB-8
Flexible Shell Elements
RCB-9
Channels, Covers, and Bonnets
RCB-10
Nozzles
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Table of Contents
PART – II
TEMA TYPE SELECTION
1
Classification of STHEs based on Service
2
Front End Head Type and its Application
3
Shell Type and its Applications
4
Rear End Head Type
(Classification of STHE based on Construction)
5
Rear End Head Type (Design Features and Applications)
6
TEMA Type Selection Guide
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PART - I
SHELL AND TUBE HEAT EXCHANGER
BASIC CONSTRUCTION
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What is a Shell and Tube Heat Exchanger
SHELL AND TUBE HEAT EXCHANGER
A shell and tube heat exchanger is a class of heat exchanger designs. It is the most common type of heat exchanger in
oil refineries and other large chemical processes, and is suited for higher pressure applications.
As the name implies, this heat exchanger consist of two sides: the shell side and tube side. Heat is exchanged along
the tube bundle surface by flowing hot fluid on one side, and cold fluid on the other.
Fluid A in
Fluid B out
Fluid A out
TUBE-SIDE
Fluid B in
SHELL-SIDE
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N-2 Nomenclature of Heat Exchanger Components
Channel Cover
Nozzle
Tubes
Girth Flange
TUBE-SIDE
SHELL-SIDE
TEMA Type: AES
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N-1.2 TEMA Type Designation
Figure N-1.2
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RCB-1 TEMA Class Designation
TEMA CLASS
APPLICATION
R
Specify design and fabrication of unfired shell and tube heat
exchangers for the generally sever requirements of
petroleum and related processing applications.
C
Specify design and fabrication of unfired shell and tube heat
exchangers for the generally moderate requirements of
commercial and general process applications.
B
Specify design and fabrication of unfired shell and tube heat
exchangers for chemical process service.
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RCB-2 Tubes
RCB-2.2
1.
TWO TYPES OF TUBES:
RCB-2.4
TUBE PATTERNS
Bare Tubes
Application: General
*
2.
Integrally Finned Tubes
Application: Shell side fluid with a low heat
transfer coefficient
Tube Pitch
= 1.25 d
Smooth Bore
* Flow arrows are perpendicular
to the baffle cut edge.
With Internal Rib
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RCB-3 Shells and Shell Covers
Shells and Shell Covers
It is found that a more economical heat exchanger can be designed by making a shell diameter smaller and a shell length
larger according to practical factors as plant layout, installation, and service.
Shell
Shell Cover
Saddle
Bracket
Horizontal Heat Exchanger
Reinforcing Pad
Shell
Rib
Web
Rib
Baseplate
Saddle Support
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Baseplate
Bracket Support
Vertical Heat Exchanger
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RCB-4 Baffles and Support Plates
APPLICATIONS:
RCB-4.5
Spacing of Baffles & Support Plates
(1) For supporting tubes
(2) For maintaining tube spacing
(3) For directing shell-side fluid across or along
tube bundles
RCB-4.1
Types of Transverse Baffles
Per RCB-4.5
Note:
Ideal baffle spacing and baffle cut shall be applied
to avoid occurrence of eddies that will cause
excessive pressure drop on the shell side.
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RCB-4 Baffles and Support Plates
RCB-4.6 Impingement Protection
RCB-4.7 Tie Rods and Spacers
Erosion of tube bundle components should be prevented or
minimized at the entrance in case of high velocity fluids.
The baffle system is tied together with tie rods and
spacers. ( Qty x Size = min. 4 x 9.5 dia. )
Spacer
Tie Rod
Baffle System
RCB-4.8 Sealing Devices
Sealing devices should be installed when necessary to
prevent excessive by-passing of a fluid around or through
the tube bundle.
Tube Layout without Sealing Devices
Tube Layout with Sealing Devices:
(Excessive bypassing of a fluid)
(1) Seal Strips (2) Dummy Tubes (3) Tie Rods w/ Spacers
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RCB-4 Baffles and Support Plates
RCB-4.9 Kettle Type Reboilers
Skid Bar Application for Bundle Removal
For kettle type reboilers, skid bars and a
bundle hold-down may be provided.
API 660 recommends skid bar application for all removable
bundles with a mass of more than 5,450kg to facilitate bundle
removal.
Sliding Shoe and/or Guide Rail (For kettle type application)
Bundle Hold Down
(Support Band)
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Sliding Shoe (For non-kettle type application)
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RCB-5 Floating End Construction
Floating End Construction
FLOATING HEAD
RCB-5.1
BACKING DEVICE
INTERNAL FLOATING HEAD
FLOATING HEAD
COVER FLANGE
FLOATING HEAD COVER
SHELL COVER
PACKING BOX
FLOATING
TUBESHEET
PACKING GLAND
SLIP-ON
BACKING FLANGE
RCB-5.2
SPLIT SHEAR RING
FLOATING
TUBESHEET SKIRT
PACKING BOX
PACKING
RCB-5.3
FLOATING
PACKING
TUBESHEET
LANTERN RING
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RCB-6 Gaskets
Gaskets
A gasket is a mechanical seal that fills the space between two objects, generally to prevent leakage between the two
objects under compression. Illustration below shows typical gasket locations for heat exchanger applications.
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RCB-6 Gaskets
Type of Gasket
Cross Section / Parts
Application
- suitable for both low and high
pressure and temperature
applications
METALLIC
SEMI
Spiral Wound (SW)
outer ring
filler
(center ring)
Metal Jacketed (MJ)
double jacket
filler
single jacket
METALLIC
NON
METALLIC
Ring Type Joint (RTJ)
oval section
octagonal section
Solid Flat Metal (SFM)
Non Asbestos (NA)
Polytetrafluoroethylene
(PTFE)
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inner ring
jacket
- for internal floating head joints
- all joints w/ pressure 300psi & over
- all joints in contact w/ hydrocarbon
- suitable for high pressure and
temperature applications since high
loads are required to seat gasket to
mating flange
- for internal floating head joints
- all joints w/ pressure 300psi & over
- all joints in contact w/ hydrocarbon
- for low pressure class application
- usually applied on internal flanges
- for low pressure class application
- usually applied on internal flanges
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RCB-7 Tubesheet
Tubesheet
RCB-7.3
Tube to Tubesheet Joint
It is the principal barrier between the shell-side and
tube-side fluids. Below are some typical tubesheet
connections to channel and shell.
Removable
Tube Bundle
Non Removable
Tube Bundle
RCB-7.513
Tube Projection
The maximum tube projection shall be 0.5 x Tube OD. In
case of vertical heat exchangers, tubes shall be flush on
the top tubesheet.
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RCB-8 Flexible Shell Elements
RCB-8
Flexible Shell Elements
Flexible shell elements or expansion joints are
applied for accommodating differential thermal
expansion of heat exchanger shells and tube
bundle carrying high temperature fluids.
Flexible shell elements, or
expansion joints
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RCB-9 Channels, Covers, and Bonnets
RCB-9.1
Channels and Bonnets
RCB-9.13 Pass Partition Plates
Shell-side flow
Partition plates attached to channels or bonnets control tube-side passes.
Pass Partition Plate
No.
of
Pass
2 PASS
Tube Side Flow
1
U-TUBE
STRAIGHT TUBE
FRONT
BACK
FRONT
BACK
1
1
1
1
2
2
2
2
1
1
2
2
Shell Side
Flow
Channel Cover
Channel
Bonnet
4
1
2
1
2
3
4
3
4
3
2
3
4
2
4
NOTE:
(1) Two phase flow on the tube side is best
kept in a single straight tube or in a U-tube.
6
(2) Odd number of passes are uncommon,
and may result in mechanical and thermal
problems in fabrication and operation.
1
2
1
1
2
4
3
4
3
5
6
5
6
1
3
2
3
2
4
5
4
5
6
6
Commonly Used Pass Partition Layout corresponding to No. of Tube Pass
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RCB-10 Nozzles
TYPE
WELDING
NECK
ILLUSTRATION
APPLICATION
Flange
Flange
Boss
Neck
Pad
Type-2A
Type-2
Type-1
Type-1
With Reinforcing Pad
- Normal application
Type-2
Self Reinforced Nozzle
- Heavy wall vessel application
Type-2A
- For cyclic service & low alloy
vessel application
LONG
WELDING
NECK
- Small nozzle application,
normally 2” and below
FORGED
NECK
- Small nozzle application,
normally 2” and below on heavy
wall vessel, cyclic service, and
low alloy application
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RCB-10 Nozzles
TYPE OF FLANGES
Welding Neck
Lap Joint
Socket Weld
Slip-On
Threaded
The flange swivels
freely on the stub
and permits bolt
hole alignment.
Suitable for a
small nozzle
where an internal
weld is difficult.
For sizes 4” and
smaller, it has
same strength as
slip-on flanges.
Requires less
accuracy in pipe
cutting and
permits bolt hole
alignment.
Low pressure
application
(Normally Applied)
Severe Service
Provides greatest
safety factor and
fatigue strength.
TYPE OF FLANGE FACE
(Normally Applied)
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BOLTING
Minimum Bolt: ¾”
≤ 1” - Coarse Thread Series
> 1” - 8UN Thread Series
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Accessories
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Accessories
JACK SCREW
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DOWEL PINS
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PART - II
SHELL AND TUBE HEAT EXCHANGER
TEMA TYPE SELECTION
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1. Classification of STHE based on Service
Heat Exchanger – both sides are process streams (that is, not a utility).
Cooler – one stream of a process fluid, and the other of cooling water or air.
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1. Classification of STHE based on Service
Heater – one stream of a process fluid, and the other a hot utility, such as steam or hot oil
Condenser - one stream of a condensing vapor, and the other cooling water or air.
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1. Classification of STHE based on Service
Chiller – one stream of a process fluid being condensed at sub-atmospheric temperatures, and the other a
boiling refrigerant or process stream
Reboiler - one stream of a bottom one from a distillation column, and the other a hot utility (steam or hot oil)
or a process stream
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2. Front End Head Type and its Applications
Front End Type
Applications
A
Fouling tube side
Cooling water in the tube side
Channel &
Removable Cover
B
Bonnet
(Integral Cover)
C
Channel Integral
with Tubesheet &
Removable Cover
N
Channel Integral
with Tubesheet &
Removable Cover
D
Clean tube side
High pressure
Toxic service
Very toxic service in the tube side
(A tubesheet is fixed to a channel to avoid
gasketed joints that may cause leakage.)
Very toxic service in the tube and shell sides
(A tubesheet is fixed to the channel and shell to
avoid gasketed joints that may cause leakage.)
Special high pressure closure application
Special High
Pressure Closure
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3. Shell Type and its Applications
Shell Type
Applications
Remarks
E
Normally applied
except in cases
below
Single phase or two phase fluid application
Temperature cross
High heat transfer efficiency but increased pressure drop
Rarely used because of the problem associated with longitudinal baffle
joints in the shell side
Vaporizing
≤ 3m tube length
Low pressure drop, usually employed in a horizontal thermosyphon
reboiler
Liquid (at the inlet) and liquid/vapor (two phases at the outlet)
Vaporizing
> 3m tube length
Low pressure drop, usually employed in a horizontal thermosyphon
reboiler
Liquid (at the inlet) and liquid/vapor (two phases at the outlet)
Condensing
Low pressure drop like condensing in vacuum
Vapor (at the inlet) and vapor/liquid (two phases at the outlet)
Condensing
Extremely low pressure drop like condensing in vacuum
Partially vaporizing
shell fluid
Kettle shell serving as vapor disengaging space
One-Pass Shell
F
Two-Pass Shell
G
Split Flow
H
Double Split Flow
J
Divided Flow
X
Cross Flow
K
Kettle Type Reboiler
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4. Rear End Head Type
CLASSIFICATION OF STHE BASED ON CONSTRUCTION
Fixed Tube Sheet Exchanger
U-Tube Exchanger
Floating Head Exchanger
Normally applied
See section 5 for
comparison of
design features.
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5. Rear End Head Type (Design Features and Applications)
FIXED TUBESHEET
L/M
U-TUBE
U
FLOATING HEAD
S
Clean Shell side
Clean Tube side
Fouling on Tube Side
High or Low
High or Low
Up to 4.0 MPa
Volatile or Toxic
Volatile or Toxic
Volatile or Toxic
No. of Tube Pass
Single or Multi Pass
Multi Pass
(Single Pass design is not possible.)
Single or Multi Pass
Bundle Removal
No
Yes
Yes
Tube Replacement
Yes
Outer Tube Only
(Difficult to replace inside tubes)
Yes
Thermal Expansion
Yes
(Expansion joints are used.)
Yes
(Each tube can expand or contract
independently.)
Yes
Heat Surface for a
given Shell ID
3
2
1
Cost Comparison
(1 as cheapest)
1
(If no expansion joint)
2
3
General Application
Design Pressure and
Temperature
Applicable Fluid
REMARKS
Basically, for horizontal STHE:
 Type L is for single pass.
 Type M is multi pass.
 Type N is applied for high
pressure and very toxic service.
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Not suited for vertical heat
exchangers.
 Type T is suited for kettle type
reboiler where U-tube cannot be
employed.
 Type P and W are for nonvolatile and non-toxic service
with design pressure limited by
its packing material.
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6. TEMA Type Selection Guide
To select the most suitable TEMA type for each given application, lots of design factors are involved as follows:
Design Conditions
 Design Pressure
 Thermal Expansion
Service Fluid
 Toxicity
 Fouling Resistance
 Vaporizing/Condensing
 Pressure Drop
Mechanical Aspect
 Vertical/Horizontal
 No. of tube pass
 Nozzle Location
 Cleaning Method
Application
 Heat Exchanger
 Cooler or Heater
 Condenser
 Chiller or Reboiler
Typical TEMA Type Configurations:
U-TUBE
BEU
FIXED TUBESHEET
BJU
AEM
FLOATING HEAD
AEL
AES
AKU
AJS
BHU
BGU
BEM
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BEL
AES
BEM
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6. TEMA Type Selection Guide
Obviously, it is not possible to cover all aspects of design or all available TEMA types of heat exchangerd in this guide.
As a General Guide for TEMA Type Selection, simple guideline is layout below:
Select an applicable case and determine a type of rear end head:
CASE-1
CASE-2
CASE-3
CASE-4
Shell Side
Tube Side
Shell Side
Tube Side
Shell Side
Tube Side
Shell Side
Tube Side
Clean
Clean
Fouling
Clean
Clean
Fouling
Fouling
Fouling
(Clean)
(Clean-Foul)
STEP-1
(1 pass)
FIXED
(1 pass)
FLOATING
STANDARD FORM
U-TUBE
B
E
U
(multi pass)
FIXED
A
E
M
(multi pass)
FLOATING
A
E
L
(single pass)
A
E
S
STEP-2
Standard Form Compliance Check:
 Shell type shall conform with Section-3.
 Front end head shall conform with Section-2.
 Equipment orientation and nozzle location are to be considered. See Typical TEMA Type Configurations.
NOTES:
(1) Clean service has a fouling resistance of < 0.0002 m2-K/W or < 0.00034 m2-K/W + chemical cleaning.
(2) Clean-Foul has a fouling resistance of 0.0002 m2-K/W to < 0.00034 m2-K/W.
(3) Fouling service has a fouling resistance of ≥ 0.00034 m2-K/W.
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CODES AND STANDARDS
CODES AND STANDARDS OF SHELL AND TUBE HEAT EXCHANGERS
1.
TEMA 9th Edition - Standards of the Tubular Exchanger Manufacturer’s Association
2.
API 660 7th Edition – S&T Heat Exchangers for General Refinery Services
3.
ASME VIII, Part UHX 2008 Edition – Rules for Shell and Tube Heat Exchangers
CODES AND STANDARDS OF NOZZLE FLANGES
1.
ASME B16.5 2003 Edition – Pipe Flanges and Flange Fittings (up to NPS 24)
2.
ASME B16.47 2006 Edition – Large Diameter Steel Flanges (NPS 26 – NPS 60)
*** END ***
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