23603752 fabrication of pressure 32 68
TRANSCRIPT
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INPLANT TRAINING REPORT
MAIN PARTS :-
1. SHELLS.
2. NOZZLES.
3. FLANGE.
4. DISH END.
5. MANWAY DEVIT.
6. SADDLE.
THE VESSEL WAS MANUFACTURED IN TWO SECTIONS.
DESCRIPTION OF PARTS :-
NOZZLES :-
Nozzles are the openings provided on job for the process
or functional requirements.These openings may be in the form of
flange connections or threaded connections or pipe.
Various types of Nozzle:
1) Inlet.
2) Outlet.
3) Man way hole.
4) Sight glass.
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PRESSURE VESSEL
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INPLANT TRAINING REPORT
5) Level indicator.
6) Drain.
DISHENDS :-
WHY DISHENDS ARE USED?
Dish end are used to with-stand high Pressure without bulging.
Flat ends are likely to bulge.
Dish ends have greater surface area.
Inside pressure is equally distributed on greater surface area
and hence Intensity of pressure is reduced.
Pressure act radial.
Bulge
Cover ShellInside Pressure Distribution
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INPLANT TRAINING REPORT
Dish end Shell
Inside Pressure Distribution
SADDLE
They are supports welded on equipments.
They are used to support and ground the equipments at site.
Horizontal support are used with saddle pads having
corners rounded off to avoid Stress concentration and a hole known
as a vent hole is drilled to vent out all air entrapped duringwelding. It is very important to ensure that the vent hole is drilled
when the completed equipment is to be heat treated.
Types of saddle:-
1) Fixed saddle : foundation holes round.
2) Movable saddle : foundation holes elliptical sometimes
provided with rollers to allow
expansion.
VARIOUS STAGES FOR FABRICATION OF VESSEL
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INPLANT TRAINING REPORT
RAW MATERIAL IDENTIFICATION
Material Quality, Thick. & Size Drawing.
Verify HT No., Plate No. & Insp. ID - Material & TC.
Verify Properties reported in TC ASME.
Verify NDT (UT) requirement.
Look for Pitting, Surface Damage / Defect on both sides.
Once the plate is identified by the Inspection &
stamped, it is now released for marking, cutting, & rolling of plate.
PROCEDURE FOR MARKING, CUTTING ANDCHECKING OF SHELL PLATE
W
L
PROCEDURE FOR PLATE CUTTING & WEP PREPARATION
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K1
ROLLING DIR.
K2
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INPLANT TRAINING REPORT
Receive the plate in PPS.
Do identification & clear from Inspection.
Mark (As per PCR) keeping 3mm extra for machining /
grinding allowance.
Carry out gas cutting of the extra portion (leaving 3mm
machining/grinding allowance) by heating up to 200 deg.C
where cutting has to be done.
Outer edges to be rounded off to 4R.
Carryout edge planning /grinding of HAZ.
In case any serration left after WEP preparation, to be
rectified as per Shop weld repair plan.
EDGE BREAKING
After cutting the plate, it is edge-breaked at both
the ends with the help of hydraulic press.
A suitable die & punch is being
used for forming operation. This is done because two ends
should meet efficiently while being rolled.
The plate is then rolled into shell in the rolling m/c.
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INPLANT TRAINING REPORT
ROLLING-FORMING
A pyramid type rolling m/c is used for this purpose.
A template is prepared with respect to the inside circumferenceof the rolled shell during the rolling operation &
accordingly the rolling is progressed.
By slowly reducing the distance between upper roller &
lower roller , plate is rolled step by step.
For Rolling of shell:- Proper edge breaking.
Clean plate & rolls before rolling to avoid pits & dents.
Check proper direction & side for rolling.
Check WEP sides [inside or outside].
LONG SEAM S/UPS :- Check geometry of weld groove.
Check circumference requirements [same to match mating
parts Tolerance as per Route card].
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INPLANT TRAINING REPORT
Mark center lines on shell calculate offset if any (circumference
differencei6.28) tack guide plates.
Match center line orientation maintain root gap.
Maintain offset (if any) i.e. radial difference.
Tack in sequence (opposite sides).
Check alignment for error.
A Various Checks for c/s
setup
Check whether all ndt is cleared on all mating parts.
Ensure long seam orientation is as per drawing.
Use qualified welder/fab.for tacking and follow weld plan.
Check push through gauge req. Alignment Of shell as per route
card.
During welding of lower thk. Shells provide inside supports,
rings to avoid distortion use Poisson plate in case of S.S.
Check offset.
For welding check feasability of welding from inside if req.
Change process in consultating with planning.
Inside welds to be ground flush only as per req. For tube
bundle assembly.
NOZZLE CUT OUT MARKING
Nozzle OD SPIRIT LEVELSTRAIGHT EDGE
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INPLANT TRAINING REPORT
OFFSET
Before marking ref. face of shell to be made true.
If ref. items is not available mark ref. taking actual thk. or ht.
Of ref. item.
All center lines should be legibly punched and circled with
paint for future ref.
Nozzle cutout to be marked after checking actual dia. of
nozzle.
Cutting to be done using profile cutting machine.
Clear NDT on WEP as per Test plans.
Nozzle set up:-
Check shape of reinf. Pads after cutting. Correct if necessary.
Ensure tell tale holes are drilled and tapped as per drawing.
Nozzles to be tried out separately on reinf pads.
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INPLANT TRAINING REPORT
While doing nozzle set up ensure extra projection is cut of
before doing setup however care to be taken to ensure heat
nos. are transferred and stamped if the same goes in cutting.
During welding ensure supports are provided inside & outside
to control distortion [additional care to be taken In case of
heat exchanger].
Check gasket face requirement as per drg. and protect all
gasket face.
In case of gasket face requiring overlay same should be carried
out in advance and clear all NDT before set up on shell.
Welding
Process of joining metals / alloys.
The process performed by Heat with or without Pressure.
Filler metal may or may not be used.
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INPLANT TRAINING REPORT
The joint will be homogeneous.
Classification Of Welding :- Pressure Welding
With Heat & Pressure.
Fusion Welding
With Heat & mostly with Filler.
Pressure Welding Process :-
Metal parts heated to forging temperature.
Heating by Oven, Oxy fuel flame or Electric Resistance.
Pressure applied on heated parts by Hammer, Hydraulic
Press or Mechanical lever.
The parts remain permanent homogeneous joint.
Fusion Welding Process :-
Metal parts locally heated to melt along the joint.
Heating by oxy fuel flame or electric Arc.
Invariably filler metal added to molten pool.
On cooling, molten puddle solidifies to permanent
homogeneous joint.
Types of Fusion Welding
Shielded Metal Arc Welding- SMAW.
Gas Tungsten Arc Welding GTAW.
Gas Metal Arc Welding - MIG / MAG.
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INPLANT TRAINING REPORT
Submerged Arc Welding SAW.
Flux Cored Arc Welding FCAW.
SMAW (SHIELDED METAL ARC WELDING)
An electric Arc struck between electrode and base metal
joint.
Base metal melts under arc.
Electrode tip melts in drops and transfers to molten pool of
BM.
Electrode with Arc moves along the joint keeping constant
arc length.
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INPLANT TRAINING REPORT
On cooling pool solidifies.
Electrode
Consumable.
Metallic Wire Coated with Flux.
Conducts Current and generates Arc.
Wire melts & deposited as filler in joint.
ASME Classification Of Electrodes
E 7018
E = Electrode.
70 = UTS in 1000 psi (60/70/80/90/100/ 110)
1 = Position (1= all, 2= 1G, 1F & 2F, 3= 1G & 1F)
8 = Type of coating (0,1,2,3,5,6,8)
GMAW (GAS METAL ARC WELDING)
Arc is initiated & maintained between a continuously fed filler
metal & the base metal.
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INPLANT TRAINING REPORT
The weld pool may be protected from oxidation by shielding
gas.
Mode of Operation: - Semi-Automatic, M/C or Automatic.
MIG (Metal Inert Gas) & MAG (Metal Active Gas).
High productivity 3 kg/h or more.
Advantages
All materials can be welded.
Welding possible in all positions.
Higher deposition rates compared to SMAW.
Welding speeds are higher.
Less starts & stops.
Minimal post weld cleaning. Can be Mechanized.
Limitations
More complex, more costly & less portable eqpt.
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INPLANT TRAINING REPORT
Difficult to use in hard to reach positions.
Arc protection against air drafts.
FCAW (FLUX CORED ARC WELDING)
An Arc Welding Process which uses continuous fed tubular
filler wire filled with flux in its core, which contains metallic &
non-metallic ingredients.
Advantages of Flux Cored wires
FCAW combines characteristics of SMAW, GMAW, & SAW.
Continuous Wire Welding.
Presence of Flux Makes Positional Welding Possible.
Metallurgical Benefits from Flux.
SAW (SUBMERGED ARC WELDING)
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INPLANT TRAINING REPORT
Fusion Welding Process.
Automatic / Semi Automatic.
Arc between Consumable Electrode and Work.
Arc Covered Under granular Flux.
Wire / Electrode Continuously Fed to Weld Pool.
Wire / Arc under Flux Moves along the Groove.
Wire, BM & Flux Close to Arc Melt Under Flux.
On Cooling Weld Metal Solidifies.
Molten Flux Forms Thick Slag Coating on Weld.
Flux For SAW
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INPLANT TRAINING REPORT
Sodium Chloride.
Potassium Chloride.
Titanium Dioxide.
Sodium Silicate.
Deoxidizing Agents.
Function Of Flux
Stabilizes Arc.
Prevents contamination of weld metal.
Cleans the weld from unwanted impurities.
Increases Fluidity of molten metal.
Generates inert gas shielding while metal transfers. Forms slag after melting & covers weld.
Allows deposited metal to cool slowly.
Compensates alloying elements within the weld.
Eliminates spatter generation.
Helps in even & uniform bead finish.
SAW Features
High productivity.
Thicker sections.
Mostly ferrous materials.
Bulky, expensive and heavy equipment.
Flat and horizontal positions only.
SAW Wire Electrode
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INPLANT TRAINING REPORT
Consumable Electrode / Wire.
Layer Wound On Spool / Coil.
CS & LAS Wires Coated with Cu.
Conducts Current and generates Arc.
Chemistry Compatible To Base Metal.
Grade Of Flux Can Be Same For CS & LAS.
Wire melts & deposited as filler in joint.
HEAT TREATMENT
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INPLANT TRAINING REPORT
Preheating
Heating the base metal along the weld joint to a
predetermined minimum temperature immediately beforestarting the weld.
Heating by Oxy fuel flame or electric resistant coil.
Heating from opposite side of welding wherever possible.
Temperature to be verified by thermo chalks prior to
starting the weld.
Why Preheating? Preheating eliminates possible cracking of weld and HAZ.
Applicable to
Hardenable low alloy steels of all thickness.
Carbon steels of thickness above 25 mm.
Restrained welds of all thickness.
Preheating temperature vary from 75C to 200C
depending on hardenability of material, thickness & joint
restrain.
How does Preheating Eliminate Crack? Preheating promotes slow cooling of weld and HAZ.
Slow cooling softens or prevents hardening of weld and
HAZ.
Soft material not prone to crack even in restrained
condition.
Post Heating
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INPLANT TRAINING REPORT
Raising the pre heating temperature of the weld joint to a
predetermined temperature range (250 C to 350 C) for a
minimum period of time (3 Hrs) before the weld cools downto room temperature.
Post heating performed when welding is completed or
terminated any time in between.
Heating by Oxy fuel flame or electric resistant coil.
Heating from opposite side of welding wherever possible.
Temperature verified by thermo chalks during the period.
Why Post Heating? Post heating eliminates possible delayed cracking of
weld and HAZ.
Applicable to
Thicker hardenable low alloy steels.
Restrained hardenable welds of all thickness.
Post heating temperature and duration depends on
hardenability of material, thickness & joint restrain.
How does Post Heating Eliminate Crack?
SAW introduces hydrogen in weld metal.
Entrapped hydrogen in weld metal induces delayed
cracks unless removed before cooling to room
temperature.
Retaining the weld at a higher temperature for a
longer duration allows the hydrogen to come out of weld.
Intermediate Stress Relieving Heat treating a subassembly in a furnace to a
predetermined cycle immediately on completion of critical
restrained weld joint / joints without allowing the welds to go
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INPLANT TRAINING REPORT
down the pre heat temperature. Rate of heating, Soaking
temperature, Soaking time and rate of cooling depends on
material quality and thickness.
Applicable to
Highly restrained air hardenable material.
Why Intermediate Stress Relieving?
Restrained welds in air hardenable steel highly prone
to crack on cooling to room temperature.
Cracks due to entrapped hydrogen and built in stress. Intermediate stress relieving relieves built in stresses
and entrapped hydrogen making the joint free from crack
prone.
Inter- Pass Temperature
The temperature of a previously layed weld bead.
immediately before depositing the next bead over it
Temperature to be verified by thermo chalk prior to starting
next bead.
Applicable to
Stainless Steel.
Carbon Steel & LAS with minimum impact.
Why Inter Pass Temperature?
Control on inter pass temperature avoids overheating,
there by
Refines the weld metal with fine grains.
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INPLANT TRAINING REPORT
Improves the notch toughness properties.
Minimize the loss of alloying elements in
welds.
Reduces the distortion.
Post Weld Heat Treatment Heat treating an assembly on completion of all applicable
welding, in an enclosed furnace with controlled
heating/cooling rate and soaking at a specific temperature for
a specific time.
Rate of heating, Soaking temperature, Soaking time and
rate of cooling depends on material quality and thickness.
Applicable to
All type of CS & LAS
Why Post Weld Heat Treatment?
Welded joints retain internal stresses within the
structure.
HAZ of welds remains invariably hardened.
Post Weld Heat Treatment relieves internal stresses
and softens HAZ. This reduces the cracking tendency of the
equipment in service.
WELD DEFECTS UNDERCUT
Definition: A groove cut at the toe of the weld and left
unfilled.
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INPLANT TRAINING REPORT
Cause: High Amperage, Improper electrode angle, long
arc lengths.
Prevention: Proper welding parameter and techniques /
consumable size.
Repair: Fill the groove with proper parameters and
technique.
SPATTERS
Definition: Small particles of the weld metal expelled from
the welding operation that adhere to the base
metal surface. Cause: Long arc length, improper weld angle, high
amperage.
Prevention: Correct Cause. Also adjacent base metal can
be coated with anti-spatter solutions/ high
temperature paint.
Repair: Remove by grinding / sanding.
POROSITY
Definition: Air entrapped in the body of the weld.
Causes: Poor cleanliness, improper shielding, insufficient
deoxidants, fast cooling rate
Prevention: Eliminate Causes
Repair: Remove and reweld
SLAG INCLUSIONS
Definition: Foreign body entrapped within the weld
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INPLANT TRAINING REPORT
Cause: Insufficient cleaning, low amperage, improper
technique, Trying to weld in an area that is too
tight.
Prevention: Improve inter-bead cleaning, increase
amperage or preheat, grind out tight areas to
gain access to bottom of joint.
Repair: Remove by grinding and reweld.
ARC STRIKES
Definition: A localized coalescence outside the weld zone.
Causes: Carelessness, improper cable connections.
Prevention: In difficult areas, adjacent surfaces should be
protected with a fire blanket.
Repair: Arc strikes should be sanded smooth and tested
for cracks.
Inspection Stages for the TEST VESSEL
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INPLANT TRAINING REPORT
Stage means an Inspection / NDT Stage which is `Offered
to & `Cleared by Inspection / NDT dept during the execution of the
Job.
Non-Destructive Testing comprises of test methods used
to examine, inspect, evaluate a part or material or system
without impairing or affecting its future usefulness.
Stages can be seam specific OR Stages can be
Non seams specific (Assembly level).
Examples of Seam specific Stages are :-
SU01 - Set Up of L/S.
RT23 - RT after Final Welding.
UT61 - UT after Hydro test.
Examples of Non- Seam specific Stages are
DT35 Overall Dimensional Check.
HY04 Hydro test of Shell side.
PG01 Painting of Vessel.
Stage Types: - There are 4 types of Stages:-
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INPLANT TRAINING REPORT
RT: Radiography stages which will appear in Test Plan &
Insp.Check List and results of which is Spot oriented.
RADIOGRAPHY TESTING
Radiography is a method used for non-destructive
inspection of components and assemblies that is based on
differential absorption of penetrating radiation.
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INPLANT TRAINING REPORT
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INPLANT TRAINING REPORT
RADIOGRAPHIC EXAMINATION Advantages
Can be used with most of the materials.
Reveals the internal nature of a material, assembly or a
component.
Discloses fabrication errors & structural discontinuities.
Provides permanent record in the form of images.
Effective in determination of volumetric flaws such as slag,
inclusions & porosities.
New generation radiography systems such as direct/ digital
radiography can provide faster results.
Limitations
Impractical to use on specimens of complex geometry.
Two side accessibility is required.
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INPLANT TRAINING REPORT
Safety aspects due to radiation hazards must be considered.
UT: -Ultrasonic stages which will appear in Test Plan & Insp.Check
List and which are Spot oriented.
PULSE ECHO SYSTEM
Widely used for flaw detection.
Sound energy is transmitted in pulses.
Used in contact and immersion methods.
CRT display -
A-scan: analog display - time versus
amplitude.
B-scan: cross sectional view.
C-scan: planar view.
May be used in contact as well as immersion.
Testing of plates, pipes, forgings, castings & welds.
ULTRASONIC TRANSDUCERS
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INPLANT TRAINING REPORT
Longitudinal mode probes are used in general for straight
beam examination.
Shear wave probes are used for angle beam examination.
Higher the frequency of the probe, higher will be the
sensitivity and resolution but
Lesser penetration.
Lower the frequency of probe lesser will be the
sensitivity and resolution but higher will be the
penetration.
ULTRASONIC EXAMINATION ADVANTAGES
Testing can be carried out with one side access.
Any thickness on higher side can be tested (Superior
penetrating power).
Results are immediate.
Exact depth and locations of flaws can be estimated.
Compact and portable equipments are available.
B-C Scan Imaging , TOFD & Phased Array are new
emerging techniques where Computerized data
acquisition and post processing is possible.
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INPLANT TRAINING REPORT
Inspection:
Stages which will appear only in Inspection checklist
E.g. Set Up, Heat Treatment, Painting etc.. Other :
Stages which will appear in Test Plan & Inspection
Check List and which are not spot oriented.
E.g. PT., Ferrite Test.
PT :
Penetrant solution is applied to the surface of a
precleaned component.The l iquid is pulled into surface-
breaking defects by capil lary act ion. Excess penetrant
material is carefully cleaned from the surface. A developer
is applied to pull the trapped penetrant back to the surface
where it is spread out and forms an indication. The
indication is much easier to see than the actual defect.
Advantages of PT
Large surface areas or large volumes of parts/materials can
be inspected rapidly and at low cost.
Parts with complex geometry are routinely inspected.
Indications are produced directly on surface of the part
providing a visual image of the discontinuity.
Equipment investment is minimal.
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INPLANT TRAINING REPORT
NDT Stages
After earlier stage is cleared by L&T Default. Ready to
offer.
First Time offer Shop. Under Inspection
Generation of NDT Request Inspection. Offered toNDT.
Enter Results (Seam not fully cleared) NDT. Rework.
Re-generate of NDT request Shop. Offered to NDT.
Results Entered (All spots Cleared). NDT.Cleared.
SEQUENCE NUMBER: -
Sequence number is associated with the stage
for that particular Seam/part/Assembly.
The stage with higher sequence number cannot
be offered unless stages in that seam / part / assembly
which are having lower sequence than the stage to be
offered on that seam is cleared.
E.g. `PT after C/B is having sequence number
higher than the sequence number of `Set up Inspection
stage means that PT of C/B can not be offered unless set
up is cleared.
The stages on a seam, which can be offered
parallely, will have same sequence number.
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INPLANT TRAINING REPORT
E.g. RT before PWHT, UT before PWHT.
PARAMETER
Parameter i s qua li ty check to be performed dur ing
Inspection of a stage.
One or more quality checks can be performed
during inspection of a stage and those Parameters (Quality
Checks) can be linked to that stage in the master data.
e.g. Stage Parameters
Set up of L/S. V-Preparation.
Offset.
Root Face & Gap.
Cleanliness.
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INPLANT TRAINING REPORT
HYDROTEST
Hydrostatic: Hydro means having to do with water and
static means stationary or not changing.
A process of making sure that the pressure
vessel & heat exchanger can withstand the pressure and
temperature to which it will be subjected.
WHEN HYDROTEST IS PERFORMED
After completion of fabrication work (in shop).
When vessels are installed.
When vessels are placed in service after commissioning.
After any repairs or modifications.
Every three years.
If the vessel show any rust or any other deterioration.
WHY HYDROTEST
To prove design compatibility.
To prove integrity of the component.
To discover any leaks due to insufficient welds or materialweakness in the vessel.
TIGHTENING OF BOLTED JOINTS
Manual - trial & error.
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INPLANT TRAINING REPORT
Torquing definite load or force.
Tensioning is applied uniformly.
TORQUING :
It is an improved method of providing torque.
The force is applied by means of a hydraulic cylinder.
The force is applied uniformly.
Force applied can be very high compared to manual force and
it can be varied with pressure.
SELECTION OF PRESSURE GAUGE
Accuracy required and range.
Operating pressure range.
Operating temperature range.
PRESSURE GAUGE LOCATION
Pressure gauge to be located above the topmost level of the
vessel / Heat Exchanger.
Pressure gauge shall be located in vertical upward position.
VENT
Vents to be provided at all high points of the vessel /
Heat Exchanger for purging air entrapment while vessel in
filling
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INPLANT TRAINING REPORT
VISUAL INSPECTION DURING HYDRO
Visual shall be made for all joints.
Inspection shall be made at a pressure not less than two third
of the test pressure.
Leakage is not allowed at the time of the visual inspection.
If the test pressure exceeds 48 deg c then inspection may be
delayed until the temperature is reduced to or less than 48. No permanent deformation during and after hydro test.
WATER FILLING, PRESSURISING & INSPECTION
Water shall be filled from top nozzle and closed with test
blank.
Test blank shall be with nipple, square bar, pressure gauge
and pipe connection for venting.
Inlet valve shall remain closed till water filling.
After blanking the top nozzle with gauge and vent pipe, water
shall be pumped from bottom.
Vent pipe shall be kept open in a bucket full of water to
observe air bubbles.
Venting shall be continued till the air bubbles in the bucket
are disappeared. Close the outlet valve on top & connect the gauge to line
pressure.
Isolate the gauge at the bottom from line pressure and pump
the water in.
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INPLANT TRAINING REPORT
Raise the pressure till 50% of test pressure.
Open the inlet gauge to pressure line and verify the pressure
on both gauges.
Increase the pressure in increments of 10% of test pressure.
Stop pumping for 5 minutes after each increment of 10% of
rise in pressure.
Isolate the inlet pressure gauge when pump in operation.
Connect the inlet pressure gauge to line pressure when pump
is stopped for pressure verification.
When test pressure is reached, stop pumping, connect inlet
gauge to pressure line and hold for 30 min (as specified in
spec) and observe the vessel from distance.
Reduce the test pressure to above design pressure and
inspect all connections for leakage.
If any leakage is observed through gasket connection, repeat
the test after depressurize the vessel & tighten the studs /
nuts.
If any leakage is observed from weld or parent metal, drain
the water, repair the leak and repeat the test.
Time, temperature & pressure chart wherever specified shall
be obtained.
IMPORTANT SAFETY POINTS IN HYDROTEST
Drain the vessel only when top out let is kept open.
Use minimum 2 gauges for any hydro test.
Never use high discharge pumps for testing low volume
vessels.
(Volume less than 10 m3).
Never pressurize any vessel above test pressure.
V .J .T. I , MATUNGA Page 68
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INPLANT TRAINING REPORT