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PRESSURE VESSEL
INSPECTION & TESTING
(AIR RECIEVERS) (PVT)
Learner Guide
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TABLE OF CONTENTS
ABOUT THIS PROGRAMME PAGE 1 THE LEARNING PROCEDURE PAGE 2 TASK 1
LEARNING OBJECTIVE PAGE 3 RESOURCE NOTES PAGE 4 SELF TEST PAGE 7
TASK 2 LEARNING OBJECTIVE PAGE 8 RESOURCE NOTES PAGE 9 SELF TEST
PAGE 12 TASK 3 LEARNING OBJECTIVE PAGE 13 RESOURCE NOTES PAGE 14
SELF TEST PAGE 16
CONTACT DETAILS: https://techav.co.za
[email protected]
https://techav.co.za/mailto:[email protected]
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ABOUT THIS PROGRAMME This video based instructional programme
has been developed to enable you to conduct an inspection and
pressure test procedure on a typical pressure vessel. The
procedures discussed are based upon air receiver and the guidelines
for compliance with the National Health and safety Act of South
Africa (O.H.S Act 85 of 1993). Instruction is based at post
apprentice level. THE PROGRAMME CONSISTS OF 1. This learner
workbook. 2. A video programme (Tech AV PVT-1). The primary source
of instruction is the video programme. Resource notes, in this
workbook, provide back-up and supplementary information. The
workbook guides you through the programme. IMPORTANT NOTE Please
read through this workbook before you view the video or attempt any
practical tasks. Follow the instructions given and you will achieve
a successful result.
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THE LEARNING PROCEDURE INSTRUCTIONAL DETAILS
o Simply follow the instructions provided on each learning
objective (task). WHAT YOU WILL NEED FOR LEARNING
o This workbook is the primary input. o Tech AV video programme
PVT-1.
WHAT YOU WILL NEED FOR PRACTICAL WORK
o Access to suitable air receivers on plant. o Relevant pressure
vessel records. o Pressure testing equipment. o Your normal hand
tools. o Safety equipment as applicable (e.g. Personal protective
apparatus especially if
working above ground level). SELF EVALUATION Certain self-test
exercises are included in this workbook. The object of each is to
enable you to assess your knowledge and skills , as applicable,
after you have received the relevant learning information. SAFETY
The essence of any regulation is the assurance of safety on the
plant. On no account will you be permitted to perform any test
procedure without the express permission of a competent person.
Always inform your appointed responsible person on plant (i.e.
Engineer, Safety officer etc) whenever you intend performing any
inspection / test on any vessel.
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LEARNING OBJECTIVE TASK 1
OBJECTIVE At the end of this section you will be able to:
o Describe the definition of a pressure vessel. o Describe the
name plate information on a pressure vessel (i.e. An air receiver).
o Describe the function of basic control or safety devices
associated with air receivers.
INSTRUCTIONS
o Read the resource notes for task 1 which begins over-page. o
View the video PVT-1 up to review break number 1. o Perform the
self-check exercise number 1.
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RESOURCE NOTES 1) THE LAW Regulation specify that all apparatus
classified under the heading pressure vessels must be regularly
inspected and tested every 36 months by a competent person in the
presence of an authorised inspector. 2) DEFINITION OF A PRESSURE
VESSEL Pressure may be caused by the compression of liquids, gases,
or a combination of both, where gas or air pressure if formed above
the surface of the contained liquid. In terms of the (O.H.S Act)
the following are not classified as pressure vessels ( at least not
in respect of the inspection and test procedures we will be
covering).
o Boilers. o Any vessel in which internal pressure is less than
atmospheric pressure ( e.g.
Vacuum tanks etc). o Portable gas cylinders including:
➢ Oxy-acetylene. ➢ Handy gas. ➢ Fire extinguishers.
o A vessel with a nominal internal diameter of less than 150 mm.
o A vessel of which the product of the design pressure, in Pascal,
and the
capacity in cubic metres is less than 15 000. o A vessel of
which the design pressure is less than 40 000 pag (40 Kpag).
All pressure vessels must be fitted with a pressure release
valve which is a sealed device that has been set to release
pressure from within a vessel when the pressure exceeds the maximum
permissible certified pressure.
A container in which the interior or shell is designed to
withstand an internal pressure above that of atmospheric
pressure.
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3) NAME PLATE INFORMATION All pressure vessels must display a
name plate, which is in effect a specification plate. The details
given on such a plate should include the following :
o Manufactures name. o Country of origin. o Manufactures number.
o Date of manufacture. o Name, number and date of standard
design. o Maximum permissible operating
pressure In Pascal. o Design gauge pressure, in Pascal. o
Capacity in cubic metres. o Mark of improved inspection
authority.
(A vessel record book or register must be maintained by the
user.) STANDARD EQUIPMENT Over and above the safety pressure
release valve all pressure vessels should feature the following
devices:
o Pressure gauge indicating the operating pressure of the
vessel.
o A stop or shut off valve enabling the supply of product to be
shut off for repair / maintenance. this device should be rated to
work at the maximum vessel pressure.
o A drain-cock or drain-valve which is to provide for the
release of the vessel contents in the event of an emergency or
maintenance.
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o On most receivers a condensate-valve for the trapping and
release of moisture resulting from condensation.
o Driers, sometimes fitted, to prevent the ingress of moisture
from the compressor. o On individual units e.g. Portable
compressor, an automatic on-off switch, activated
by receiver pressure, to shut off the compressor unit when
pressure has reached a pre-set unit.
5) SOME DEFINITIONS ON PRESSURE Maximum permissible
pressure:
o The maximum pressure at which the vessel may operate.
Normal working pressure: o The pressure at which the vessel
normally operates.
N.B: Although both maximum permissible pressure and normal
working pressure may be the same - it is important to note that the
working pressure may never exceed the permissible pressure. Gauge
pressure:
o The pressure in excess of that owing to atmospheric pressure.
Design pressure:
o The pressure used by the manufacturer to formulate dimensions
/ specifications for the component parts that work under
pressure.
NOW VIEW THE VIDEO UP TO REVIEW NO. 1.
https://techav.co.za/
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SELF TEST EXERCISE TASK NO. 1
INSTRUCTIONS o Without the aid of notes or the video, answer the
following
questions. o When you have completed the exercise check your
answers
via your notes or video. QUESTIONS 1. In terms of
regulations-How frequently should a air receiver be
Inspected / Tested?
___________________________________________________________
2. Complete the following statement:
A pressure vessel is defined as being a _____________________
in
which the interior or ______________________ is designed to
withstand an internal ________________________ above that of
_________________ ______________________.
3. On the list below tick (next to relevant unit) which is not a
pressure
vessel, according to the act.
1) Air receiver.
2) Oxygen cylinder.
3) Fire extinguisher.
4. What does a red line indicate on the vessels pressure
gauge?
___________________________________________________________
5. List the details that should appear on a typical vessels name
plate.
o _____________________________________________________
o _____________________________________________________
o _____________________________________________________
o _____________________________________________________
o _____________________________________________________
o _____________________________________________________
o _____________________________________________________
o _____________________________________________________
o _____________________________________________________
YES NO
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LEARNING OBJECTIVE TASK 2
OBJECTIVE At the end of this section you will be able to :
o Effect the necessary preparatory procedure for performing a
pressure test. INSTRUCTIONS
o Read the resource notes for task 2 which begins over-page. o
View video PVT-1 up to review break number 2. o Perform self-check
exercise number 2.
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RESOURCE NOTES PREPARATION OF THE VESSEL FOR INSPECTION /
TESTING An inspection is performed upon a de-pressurerised vessel
which has been isolated and disconnected from its normal supply and
delivery line. A) PROCEDURE - PREPARATION
o Shut off the main supply stop valve. o Shut off the downstream
(outlet) stop-valve. o Slowly drain the receiver of air via the
drain-cock. o Disconnect the supply line and downstream line from
the receiver. o Remove an inspection cover, or in the case of
portable unit -remove the plug. o Clean all accessible surfaces in
order that any structural defects can be seen.
B) PROCEDURE - INSPECTION (EXTERNAL)
o Examine all visible surfaces for signs of weakness or damage
caused by corrosion, pitting or oxidation.
o Examine, with the aid of a lamp, torch and inner mirror if
necessary, the internal surfaces, checking again for signs of
weakness.
o Every weld, seam or fitting that is welded to the receiver
must be closely inspected for any sign of damage such as cracking
or corrosion.
N.B. Upon the observation of such conditions the inspector will
make an assessment of the extent of the damage. From this
assessment the vessel may have to be refurbished or scrapped
according to the extent of the weakness. C) PROCEDURE - INSPECTION
ACCESSORIES
o Inspect the receivers pressure gauge. The face must be clear
and easily visible. The maximum allowable working pressure mist be
clearly indicated on the face with a red line or red shading.
o Inspect the pressure release valve (safety valve).we need to
remove this valve during the pressure test anyway, so it may be
easier to remove it now for a physical inspection. Check that it is
not physically damaged and see that it is locked or sealed. If the
lock is missing or the seal has been broken then the valve must be
checked, re-calibrated and re-sealed by an approved authority
before it may be re-installed.
o Any valve connected to or from the receiver must be inspected
for physical damage and for its free operation between its open and
closed position.
o On portable units or individual-plants, the automatic cut out
I pressure switch should be checked for any physical damage.
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D) REPORT o All items checked should be noted on the pressure
vessel report (A typical
example of a pressure vessel record can be found on the next
page).
NOW VIEW THE VIDEO UP TO REVIEW NO. 2.
https://techav.co.za/
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SELF TEST EXERCISE TASK NO. 2
INSTRUCTIONS o Without the aid of notes or the video, answer the
following
questions. o When you have completed the exercise check your
answers
via your notes or video. QUESTIONS 1. List each point of
inspection that you would make on a typical air
receiver, and include what it is you are looking for.
1)_________________________________________________________
2)_________________________________________________________
3)_________________________________________________________
4)_________________________________________________________
5)_________________________________________________________
6)_________________________________________________________
2. Where a weakness or defect is noted what is normally
done?
__________________________________________________________
__________________________________________________________
__________________________________________________________
3. What action must be taken when a pressure valve's seal
has
been broken?
__________________________________________________________
__________________________________________________________
4. What must be noted on the pressure vessel report?
__________________________________________________________
YES NO
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LEARNING OBJECTIVE TASK 3
OBJECTIVE At the end of this section you will be able to :
o Perform a hydraulic pressure test to a typical air receiver .
INSTRUCTIONS
o Read the resource notes for task 3 which begins over-page. o
View video PVT-1 from review break no. 2 to the end of the . o
Perform self-check exercise number 3.
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RESOURCE NOTES In terms of the regulations, an air receiver must
be tested using the hydraulic method (i.e. Water is used as the
test medium). N.B: It is extremely unlikely that you would be
required to use any other test medium however some pressure
vessels, because of certain design and mass considerations may have
to be gas tested. In such cases an inert gas, such as nitrogen,
would be used. Flammable or explosive gas is never used as a test
medium. The following notes describe the general procedure used to
perform a typical hydraulic test. A) PROCEDURE -PREPARE THE
RECEIVER
o Fit covers, blank off plates or plugs to all relevant
openings. o Replace and secure hand hold covers (inspection covers
/ plates, using the
necessary sealing compounds.). o Fit a temporary air-bleed valve
to the top of the receiver, at safety valve
position. o Connect a suitable water supply to the vessel
(preferable via the normal air
supply input connection). o Connect test pump hose to convenient
connection. o Open the venting valve and fill the vessel with
water. Check and rectify any
leaks at connections during this stage. o Close off water supply
when full and close off the venting valve. o Bleed or prime the
test pump as required.
N.B: A current test certificate for the pressure gauge on the
pressure testing must be available for inspection -Check before
pressurising, that the maximum permissible operating pressure given
on the name plate agrees with the figure given on the test
certificate. B) PROCEDURE -PRESSURE TESTING Calculate the testing
pressure by multiplying the maximum permissible working pressure by
1,25 (note this figure may be given on the name plate - but still
calculate it to be sure).
o Pump the test pump until the calculated pressure is obtained.
o Check for any leaks. o Hold the test pressure for 30 minutes. o
Check for any leaks at structural points i.e. Welded seams, welded
fittings,
plugged points (secure plugs as necessary). o Note upon the
vessel report the condition of vessel whilst under hydraulic
pressure. o After 30 minutes, and after noting all conditions,
drain off the water.
N.B: Drain off slowly top avoid accidents, allow water to be
piped of to drain.
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RESOURCE NOTES B) PROCEDURE -RE-COMMISSION THE VESSEL
o When water has drained reconnect the original fittings and
accessories. o Re-charge the vessel via normal supply line and
check for leaks. o Drain of any water accumulated by : The bottom
drain cock The downstream
condensate trap (if fitted). o Check that pressure does not rise
beyond the maximum permissible
operating pressure on the vessels' gauge. o Clean up
surroundings and put tools and equipment away. o Ensure that the
vessel record is completed and signed off by the inspector. o
Advise the user that the work has been completed.
SAFETY
o The primary reason for performing the pressure vessel
inspection and test is safety. A weak or substandard vessel is a
potential bomb and it is the users responsibility to see that the
receiver is maintained in a safe condition.
o Always make sure that you adhere to the safety rules and
regulations pertaining to your plant I factory or shop whenever
working on vessels.
NOW VIEW THE VIDEO UP TO THE END OF THE PROGRAMME.
https://techav.co.za/
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SELF TEST EXERCISE TASK NO. 3
INSTRUCTIONS o Without the aid of notes or the video, give a
step by step account of
how to perform a hydraulic test on a typical air receiver. o
When you have completed this exercise, compare your response
with your notes or the video. Procedure for pressure testing a
vessel (complete below).
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YES NO
Answer 1: Answer 2: Answer 3: Answer 4: Answer 5: Answer 6:
Answer 7: Answer 8: Answer 9: Answer 10: Answer 11: Answer 12:
Answer 13: Answer 14: Answer 15: Answer 16: Check Box1: OffCheck
Box2: OffCheck Box3: OffAnswer 17: Answer 18: Answer 19: Answer 20:
Answer 21: Answer 22: Answer 23: Answer 24: Answer 25: Answer 26:
Group1: OffGroup2: OffGroup3: OffGroup4: OffGroup5: OffGroup6:
OffGroup7: OffGroup8: OffGroup9: OffGroup10: Off
