Pressure vessel, its types with different testing methods

1. Pressure Vessel, its types with
different testing and checking
methods
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Chemical Engineering Plant Design
By:
IHSAN WASSAN
U.S - Pakistan Center for Advanced Studies in Water
Mehran University of Engineering and Technology, Jamshoro

2. • Introduction to Pressure Vessels
• Types of pressure vessels
• Pressure vessels supports
• Main components of Pressure Vessel
• Fittings of Pressure Vessel
• Testing methods on pressure vessels
• Destructive and non-destructive tests
• Leak testing methods
CONTENTS
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3. • Introduction to Pressure Vessels
• Types of pressure vessels
• Pressure vessels supports
• Main components of Pressure Vessel
• Fittings of Pressure Vessel
• Testing methods on pressure vessels
• Destructive and non-destructive tests
• Leak testing methods
CONTENTS
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4. Introduction to Pressure Vessels
• Pressure vessels are containers for fluid under high pressure.
• In other words pressure vessels are the containers or envelop in which material are
processed, treated or stored which has been designed operate at pressure above
15 psi.
• Applications of pressure Vessel:
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❑ Petroleum refining
❑ Chemical
❑ Power
❑ Food and beverages
❑ Pharmaceuticals
❑ Nuclear reactors
❑ Submarines

5. • There are different types of pressure vessels :
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Types of Pressure Vessels
❑Open and closed Pressure Vessels
❑Thin and thick-walled Pressure Vessels
❑Horizontal and vertical Pressure Vessels
❑Cylindrical and spherical Pressure Vessels
❑High- and low-pressure Vessels
❑Normal and elevated pressure Vessels

6. Skirt
Pressure Vessels Supports
❑Saddle support
❑Leg support
❑Skirt support
leg
saddle

7. SECTION A-A
AHEAD
NOZZLES
A
SHELL
SADDLE SUPPORT
(SLIDING)
SADDLE SUPPORT
(FIXED)
Horizontal Drum on Saddle Supports
NOZZLE
SHELL
HEAD
HEAD
SUPPORT
LEG
Vertical Vessel with Leg Support
Different Pressure Vessels

8. Vertical Vessel
with Lug
Support
NOZZLE
NOZZLE
NOZZLE
NOZZLE SKIRT
SUPPORT
SHELL
CONE
TRAYS
HEAD
HEAD
BASE PLATE
Column
OUTLET NOZZLE
UPPER
CATALYST
BED
LOWER
CATALYST
BED
CATALYST BED
SUPPORT GRID
OUTLET
COLLECTOR
SHELL
HEAD
SUPPORT SKIRT
Reactor
Different Pressure Vessels

9. • Cylindrical or spherical shell
• Formal heads
• Blind flanges, cover plates, flanges
• Openings and nozzles
• Supporters
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Main components of Pressure Vessel
Typical components of pressure vessel are :

10. Fittings of Pressure Vessels
❑Pipe fittings, couplings, joints
❑Nozzles
❑Valves, strainers, filters , straps
❑Measuring devices (thermocouple, pressure gauge, level gauges)

11. Two primary types of tests that are performed on pressure vessels include:
1. hydrostatic and
2. pneumatic tests
The key difference between these two types is that:
hydrostatic testing uses water as the test medium, and
pneumatic testing uses a non-flammable, non-toxic gas like air or nitrogen.
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Testing methods on Pressure Vessels

12. Destructive tests
• Bend test
• Tensile test
• Impact test
• Hardness test
Non –destructive tests
Five principle methods of NDT used are:
1. Visual testing (VT)
2. Penetrant Testing (PT)
3. Magnetic Particle Testing (MPT)
4. Radiography testing (RT)
5. Ultrasonic testing (UT)
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Destructive and non-destructive tests

13. • Visual testing can give a good overview of a vessel’s general condition.
• First making sure the surface of a vessel is clean and well-lit, pressure
vessel inspectors will examine any part of the vessel they can observe.
• They will look at things like any welded seams, such as those around
appendages or along the length of the vessel’s shell.
• They may see that the vessel appears to be in good working condition, or
they may observe issues like cracking, corrosion, erosion or hydrogen
blistering.
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1. Visual testing (VT)

14. • A liquid penetrant test is a means of checking for flaws on a pressure vessel that are
open to the surface.
• First, an inspector flows a very thin liquid, known as a penetrant, into the possible flaw.
• Typically, the penetrant is sprayed on and allowed time to soak in.
• A tester can add a fluorescent chemical to the penetrant so that it will be even more
visible under ultraviolet light.
• After letting the penetrant dry, the inspector then wipes off the penetrant left on the
surface and uses a developer to draw out any penetrant that has seeped into cracks.
• As the penetrant comes up to the surface, it reveals the magnitude of the problem.
• This method of testing is most often used on welded seams, but it can also be used on
bars, plates, pipes and more. 14
2. Penetrant Testing (PT)

15. • In a magnetic particle test, the inspector runs a magnetic current through the
pressure vessel, typically using the prod method, where an electric current flows
between contact probes.
• If there are any defects in the shell’s material, a “flux leakage field” will appear.
• The flux leakage fields become visible when the inspector spreads ferromagnetic
particles on the vessel.
• In a wet magnetic particle test, these particles consist of a wet suspension in a
liquid, and in a dry magnetic particle test, they consist of a dry powder.
• As with the liquid penetrant test, the particles can be treated, so they fluoresce
under black light.
• As the metal particles are attracted to the magnetic current, they reveal the
approximate dimensions of any flaws that have created flux leakage fields.
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3. Magnetic Particle Testing (MPT)

16. • Unlike the previous three methods, radiography can detect more than flaws that
are near or on the surface — it is a volumetric method, meaning it can detect
issues inside the vessel.
• Radiography uses gamma or X-rays to produce a picture of the vessel.
• Just as with medical radiography, holes, discontinuities and other differences in
density decrease the attenuation of the X-ray, leading to greater exposure on the
film.
• On the negative film, these more exposed areas appear darker.
• Open voids will appear pretty obvious in a radiographic image, but more minor
cracks can be elusive.
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4. Radiography testing (RT)

17. • Ultrasonic testing is another volumetric method.
• It uses sound waves to measure a material’s thickness or detect any defects.
• An electronic system produces high-voltage electrical pulses, and in return, a
transducer creates high-frequency ultrasonic energy.
• As the ultrasonic sound waves move through the material, if they encounter a
discontinuity, the discontinuity will reflect back some of the energy.
• The transducer converts this reflected wave into an electrical signal, which is then
shown on a display.
• Generally speaking, ultrasonic testing must be read in real-time since it doesn’t
produce a lasting record like radiography does.
• However, some modern UT equipment is designed with a means of recording the
signals.
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5. Ultrasonic testing (UT)

18. There are different methods for pressure and leak testing in the field.
Seven important are :
1. Hydrostatic testing
2. Pneumatic or gaseous fluid testing
3. Combined pneumatic and hydrostatic testing
4. Initial service testing
5. Static head testing
6. Vacuum testing
7. Halogen and helium leak detection testing
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Leak testing Methods

19. Thank you very much!
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