2. PRESSURE VESSEL
The very important phase to construct a pressure vessel is
“DESIGN PHASE” Design phase is carried out with the care
with the help of “CODES ” . The values of which ensure the
safety performance of vessel .
“ PRESSURE VESSELS ARE VESSELS WORKING UNDER INTERNAL
OR EXTERNAL / VACUUM PRESSURE WITH VARIOUS
TEMPERATURES CONDITION.”
3. MATERIAL FOR PRESSURE
VESSELS:-
•Carbon Steel
• Carbon Manganese steel
• Carbon Manganese Silicon Steel
• Chromium Steel (1Cr.-0.5Mo. Steel , 2Cr- 1 Mo. Steel ,2- ¼
Cr. - ½ Mo. Steel )
• Stainless steel
• Titanium
Generally Carbon Steel is used to construct vessels. But
Sometimes where the corrosion is higher than the Normal
corrosion at that time Stainless Steel may be Used or sometimes
Titanium is also used due to process Requirement and highly
corrosive condition.
4. DESIGN
Pressure Vessel is contain following main equipment.
SHELL
DISHED END [ D’END]
NOZZLES
MANWAYS
LUGS
SUPPORTS
But we are looking only for Design of SHELL, DISHED END &
NOZZLES.
5. DESIGN OF SHELL
“The portion between Top D’end and Bottom D’end is known as
SHELL”
Shell is made from rectangle plate. The material used to make a shell
is SA516 GR 70. In America the SA516 means Carbon Steel and GR
means Grade. Grade is depending upon the different material which
we used for Pressure Vessel.
The thickness of shell is depending upon the type of shell and
stresses. Generally Shell can be classified in 2 categories.
1. Cylindrical Shell 2. Spherical Shell
Stress can also classified in 2 categories.
1. Circumferential Stress 2. Longitudinal Stress
6. Here,
P = Internal Design Pressure
t = Minimum Required
thickness of Shell in inches.
R = Inside radius of Shell
S = Maximum Allowable
Stress value in Psi
E = Joint Efficiency
7. DESIGN OF DISHED END
Shown in the figure , the portion above and below the shell is known
as “ DISHED-END OR HEAD ”.
The portion above the shell is known as “Top Dished-End ” and the
portion below the shell is known as “ Bottom Dished-End ” .
There are many Types of Dished-End like :
Hemispherical head
Elliptical Head
Torispherical Head
Conical Head
Toriconical Head
13. NOZZLE
Νοzzle are opening in vessel for various purpose like
inlet , outlet , pressure indicator , level indicator ,etc.
The various construction are :
1. Nozzle with Pipe & Flange
2. Nozzle with Pipe , flange & reinforcement pad
3. Long weld neck type nozzle
4. Self Reinforced Nozzles
14. 1. FLANGE PIPE
This type construction consist of a flange with pipe
intruding vessel wall.
The flanges used in such construction are generally
standard flanges from ASME B16.5. These flanges of
forged grain structure.
Another important part is pipe which is either
seamless or fabricated from plate with long seam.
Seamless Pipes are manufactured using extrusion
methods. These type of nozzles are either SET-IN type
(in which pipe enters till inside of vessel ID) or SET-ON
type (in which pipe up to OD of vessel).Generally, this
type of nozzles are used for low pressure services.
15.
16. 2. FLANGE PIPE CONSTRUCTION
WITH REINFORCEMENT PAD :
This type of construction is similar like Flange type
construction with difference of additional reinforcement
provided to compensate the reduction in strength due to cutout
in vessel wall, using pad.
As can be nicely understood from figure the pads are
provided outside the vessel wall & welded with shell using fillet
welds.
These pads are provided with 1 or 2 No of holes which is used
for removal of hot gases between pad & vessel wall during heat
17.
18. 3. LONG WELD NECK
CONSTRUCTION:
This is another type of
construction widely used in
pressure vessel. The constructional
details can be seen in figure.
Long weld neck flanges are the
flanges manufactured as per
manufacturer standards like Taylor
Forge.
These flanges are readily available
in market with various lengths.
ASME Code allows use these
19. 4. SELF REINFORCED NOZZLES:
This is the most widely used construction of High
thick vessel & reactors. In this type of construction,
the nozzle opening is made of forged material
machined to suit the shape required for reinforcement
of nozzle cutout. This construction allows very
pressures & temperatures.
