Shell and tube heat exchangers consist of tubes arranged in a shell to allow two fluids to exchange heat without mixing. They are classified based on their intended service and divided into a front head, shell, and rear head. Design considerations include tube and shell thickness, tube pattern, baffles for turbulence, tie rods and spacers to hold components, and loading conditions during operation. TEMA standards provide guidelines for construction based on size, pressure, and materials.

1. SHELL AND TUBE HEAT
EXCHANGER
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2. Shell & Tube Heat Exchanger
DEFINITION :
The shell and tube exchanger consists of a shell, with a large number of tubes,
attached to an end plate and arranged in a fashion where two fluids can exchange
heat without the fluids coming in contact with each other.
SIZE :
Size of shell & tube exchanger is designated by numbers describing shell
diameter & tube lengths.
e.g. SIZE 23-192 (591-4877) TYPE AES
SHELL AND TUBE EXCHANGER GEOMETRY
Shell and tube exchanger is divided into three parts:
 Front head,
 Shell,
 Rear head.

3. Shell & Tube Heat Exchanger

4. Shell & Tube Heat Exchanger
APPLICABILITY OF TEMA
The TEMA Mechanical Standards are applicable to shell and tube heat exchanger
which do not exceeds any of the following criteria.
 inside Diameter of 100 in. (2540 mm)
 a design pressure of 3,000 psi (20684 kPa)
 product of nominal diameter, in. (mm) & design pressure, psi (kPa) of 1,00,000
(17.5 × 106)
the intent of these parameters is to limit the maximum shell wall thickness to
approximately 3 in. (76mm),and maximum stud diameter to approximately 4 in.
(102 mm).

5. CLASSIFICATION
According to service TEMA classifies heat exchanger into three classes :
• CLASS “R” : It refers to design and fabrication of shell and tube
exchangers for severe requirements of petroleum and related processing
application.
• CLASS “C” : It refers to design and fabrication of shell and tube
exchangers for moderate requirements commercial and general process
application.
• CLASS “B” : It refers to design and fabrication of shell and tube
exchangers for chemical process service.
Shell & Tube Heat Exchanger

6. DESIGN STEPS :
 SHELL THICKNESS :
Shell thickness is calculated according to UG-27 (ASME SEC-VIII DIV 1) & is
compared with MINIMUM SHELL THICKNESS TABLE R-3.13 in TEMA .
 TUBE THICKNESS :
TEMA defines the minimum tube thickness depending upon tube O.D. and
material of construction.
Shell & Tube Heat Exchanger
 TUBE PATTERN :

7.  TUBE PITCH :
( Pitch min = 1.25 × tube O.D.) .
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 STANDARD TUBE LENGTH :
8 (2438), 10 (3048), 12 (3658), 16 (4877), and 20 (6096) ft. (mm).
 BAFFLES :
It creates turbulence inside the shell due to cross flow and also provides support
to the tubes.
TRANSVERSE BAFFLE TYPE :
SINGLE SEGMENTAL DOUBLE SEGMENTAL TRIPLE SEGMENTAL

8.  BAFFLE THICKNESS : (TEMA TABLE R-4.41)
 BAFFLE CLEARANCE : (TEMA TABLE RCB-4.3)
 TUBE HOLES IN BAFFLE :
Tube holes have over tolerance of 0.3 mm
Shell & Tube Heat Exchanger
 BAFFLE SPACING :
Minimum baffle spacing shall be greater of 1/5 of shell I.D or 51 mm.
Maximum baffle spacing depends on tube O.D. and material of construction of
tubes.
 TIE RODS AND SPACERS :
Tie rods and spacers are provided for holding and positioning the baffle
system together.

9.  TUBESHEET :
 NUMBER AND SIZE OF TIE RODS :
Tie rod diameter and minimum number of tie rods are selected based on
shell inside diameter.
Shell & Tube Heat Exchanger
 SEALING DEVICES :
Sealing devices used are seal strips, tie rods with spacers, dummy rods, or
combination of these.

10.  LOADING CONDITIONS :
1) Tube side pressure Pt acting only (Ps = 0), without differential thermal expansion.
2) Shell side pressure Ps acting only (Pt = 0), without differential thermal expansion.
3) Tube side pressure Pt and shell side pressure Ps acting simultaneously, without
differential thermal expansion.
4) Differential thermal expansion acting only (Pt = 0, Ps = 0).
5) Tube side pressure acting (Ps = 0), with differential thermal expansion.
6) Shell side pressure acting (Pt = 0), with differential thermal expansion.
7) Tube side pressure Pt and shell side pressure Ps acting simultaneously, with
differential thermal expansion.
Shell & Tube Heat Exchanger

11. THANK YOU
Shell & Tube Heat Exchanger