personal protective equipment 500
Post on 08-Apr-2018
216 Views
Preview:
TRANSCRIPT
-
8/7/2019 Personal Protective Equipment 500
1/54
2011
SHIVENDRA PRATAP SINGH
SGIL
5/2/2011
PERSONAL PROTECTIVE
EQUIPMENTS,WELDING,NDT&PWHT
-
8/7/2019 Personal Protective Equipment 500
2/54
Personal protective equipment
Supervisers are responsible to ensure personal
protectiveequipment is worn to protect
workers from potential hazards
MORE THAN ONE-FOURTH OF THESE INJURIES
WILL INVOLVE THE HEAD, EYES, HANDS, OR
FEET
Clothing that protects the body & extremities
will be worn
Loose clothing will not be worn where it can
contact or catch on energised conductors
-
8/7/2019 Personal Protective Equipment 500
3/54
,moving parts,equipment,or other hazards of
this type
UNDER THE REQUIREMENTS OF 29 CFR
1910.132, ENGINEERING CONTROLS SHALL BETHE PRIMARY METHOD USED TO ELIMINATE
HAZARD EXPOSURE IN THE WORK PLACE.
TYPES OF EYE AND FACE PROTECTION
INCLUDE:
-SAFETY GLASSES
- GOGGLES
- FACE SHIELDS
-
8/7/2019 Personal Protective Equipment 500
4/54
- WELDING HELMETS
HEAD PROTECTION:
l HELMETS AND HATS FOR THE PROTECTION OF
DOC EMPLOYEES FROM THE IMPACT OF
FALLING AND FLYING OBJECTS AND FROM
LIMITED ELECTRICAL SHOCK AND BURN SHALL
MEET THE SPECIFICATIONS OF ANSI Z89.1
HEAD PROTECTION
SHELL IS DESIGNED TO ABSORB SOME IMPACT
SUSPENSION MUST BE ADJUSTED SO SHELL IS
1.5 INCHES ABOVE THE HEAD
-
8/7/2019 Personal Protective Equipment 500
5/54
HARD HATS ARE TESTED TO WITHSTAND
IMPACT OF 8 LB WEIGHT DROPPED FROM 5 FT
HARD HATS MUST ALSO MEET WEIGHT,
FLAMMABILITY AND ELECTRICAL INSULATION
STANDARDS
(HARD HAT)
FOOT PROTECTION
l FOOT INJURIES ARE MOST LIKELY TO OCCURWITH:
HEAVY OBJECTS FALLING ON YOUR FEET
ROLLING OF HEAVY OBJECTS
PIERCING OF OBJECTS THROUGH SOLES OF
YOUR SHOE
FEW POINTS REMEMBERED FOR
PREVENTING FOOT INJURIES
-
8/7/2019 Personal Protective Equipment 500
6/54
IF WORKING AROUND ELECTRICAL WIRES,
BOOTS/SHOES MUST BE METAL FREE AND
NON-CONDUCTIVE
STATIC FREE ENVIRONMENTS REQUIRE
CONDUCTIVE SHOES
RUBBER OR SYNTHETIC FOOTWEAR MAY BE
REQUIRED AROUND CHEMICALS
AVOID LEATHER SHOES/BOOTS AROUND
CORROSIVES
FOOT GUARDS AND HEEL AND ANKLE
SHIELDS MAY BE REQUIRED FOR
PARTICULAR WORK
(SAFETY BOOTS)
HAND PROTECTION
-
8/7/2019 Personal Protective Equipment 500
7/54
FINGERS, HANDS AND ARMS ARE INJURED
MORE THAN OTHER PARTS OF THE BODY
GLOVES ARE THE MOST COMMON PROTECTORS
FOR THE HANDS
BARRIER CREMES MAY BE USED AS HAND
PROTECTION OR, IN CONJUCTION WITH OTHER
HAND PROTECTION
HAND GLOVES (RUBBER)
HEARING PROTECTIONREQUIRED WHEN NOISE MEETS OR EXCEEDS
85DBA.IF YOU HAVE TO YELL TO BE HEARD
,WEAR EARPLUGS
(EAR PLUGS)
-
8/7/2019 Personal Protective Equipment 500
8/54
SAFETY GLASSES-
To be worn at all times when in constructional
area.Additional eye/face protection should be
wornwhen theres a possibility of flying debrisfor work being performed by either the
employee or others in the area-
Working with crushing equipment
Hammering,chipping,drilling
Cutting with disc or power-driven saw andother cutting under tension
Any grinding work
Use of compressed air ,water or other
liquid/solutions with shot,injection or
other abrasive cleaning
Use and handling cartridge-operated tools.
Working with chemical solid-liquid
substances
Concrete(spraying&vibration) pouring.
Coiling rebar/cable and related
operations,such as cable straightening. Strapping and unstrapping under tension.
Handling of glass either whole or broken.
-
8/7/2019 Personal Protective Equipment 500
9/54
Approved dark/tinted safety glasses should be worn when
working in the bright sunlight.However ,clear glasses
should be worn at night and when inside buildings or in
covered areas with limited lightingsPerforming abrasive
blasting work.
Face shields-
Face shields must be worn in addition to safety
glasses when
performing,cutting,grinding,hammering,chippi
ng,handling hazardous liquids,abrasive
blasting,cartridge operated tools and concrete
work.
-
8/7/2019 Personal Protective Equipment 500
10/54
Welding
a localized coalescence of metals or non metals
produced either-
By heating the materials to the welding
temperature ,with or without the application of
pressure or
By the application of pressure alone and with
or without the use of filler metal.
-
8/7/2019 Personal Protective Equipment 500
11/54
Common welding process
Shielded metal arc welding(SMAW)
Gas tungsten arc welding(GTAW)
Gas metal arc welding(GMAW)
Flux cored arc welding(FCAW)
Submerged arc welding(SAW)
GMAW PROCESS
Popularly known as MIG process.
-
8/7/2019 Personal Protective Equipment 500
12/54
It is a semi-automatic process.
Uses gases(co2,argon or mix)for
shielding.
Uses continuous solid metal wire
feed.
No deposition of slag.
High productivity 3kg/hr or more
GMAW EQUIPMENTS
-
8/7/2019 Personal Protective Equipment 500
13/54
Welding power source
Wire feeder mechanism
Gun with gas supply & trigger switch
-manual(semi automatic)guns
-automatic torches available
Flux core arc welding
Similar to GMAW process except that the
electrode is tubular containing a granular
flux.
-
8/7/2019 Personal Protective Equipment 500
14/54
Shielding gas may or may not be used
depending on the type of electrode
used(eg. Self-shielded flux cored wires do
not require gas shielding).
Solidified weld metal is covered by a layer
of slag.
Equipment used is identical to gmaw
except high current capacity guns and
power sources.
Equipment set upFCAW
Torch
Electric power source
Shielded gas source
Wire spool with wire drive control
-
8/7/2019 Personal Protective Equipment 500
15/54
Torch gas mixture
Inert gas (MIG)
-Argon or helium or mixture of these
Active gases(MAG&FCAW)
-Carbon dioxide
-argon plus oxygen and/or carbon dioxide
-nitrogen,hydrogen
ELECTRODE/ROD CLASSIFICATION AS PER
AWS
EXXT-X
WHERE-
E-electrode rod
X-minimum tensile strength in ten thousand
psi
X-position (0- F&H,1-ALL Positions)
T-tubular electrode
X-chemical composition/operati
characterstics
-
8/7/2019 Personal Protective Equipment 500
16/54
ADVANTAGES-
High efficiency due to increased deposition
rate. Good performance on contaminated surfaces.
Baking process of electrodes eliminated.
Can be used for field applications.
Deep penetrating arc reduces the possibility of
fusion problems.
Frequent changing of electrode is eliminated.
Metal conversion factor is upto 95%.
LIMITATION-
Presence of a layer of solidified slag
Smoke generated is more than in
GMAW&SMAW.
Equipment required is more complex.
Slag inclusion due to trapping slag within
the weld deposit.
Not advisable for pipe thickness less than
12.5mm.
Requires proper wind shielding.
High travel speed is required.
-
8/7/2019 Personal Protective Equipment 500
17/54
SMAW FCAW
-Slower process -faster process
-example- -for the
same joint
For a 30*12.7mm joint, it takes
only 1.5hrs
It takes 4.5hrs
-for a weldolet of 16*10 -for the
same weld it
It takes 7 hrs takes only
2.15 hours
FCAW IS THREE(3) TIMES FASTER THAN SMAW
Welding position
-
8/7/2019 Personal Protective Equipment 500
18/54
WELD FINISH
BUTT WELD-
(BUTT WELD)
-
8/7/2019 Personal Protective Equipment 500
19/54
Butt welding is a metalwelding process in which round or profilestock is welded end to end.
Butt welding can be used to run a processing machine continuously,as opposed to having to restart such machine with a new supply ofmetals.
Usually, the seams (or abutment sections) are cleaned andprepared, and set on an automated piece of equipment which then
welds the two materials together.Afterward, the material isusually ground down to a smooth finish and either sent on its wayto the processing machine, or sold as a completed product.
WELD FINISH-WELDOLET
http://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Weldinghttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Welding -
8/7/2019 Personal Protective Equipment 500
20/54
Weldolet are basically self reinforced fittings.
Weldolet is used for Butt weld branch connection where standard tee
is not
available due to size restrictions and the piping is of critical / high
pressure service.
Weld finish-trunion
-
8/7/2019 Personal Protective Equipment 500
21/54
Weld finish-branch with RF pad
-
8/7/2019 Personal Protective Equipment 500
22/54
MACHINES USED AT PFS-
-
8/7/2019 Personal Protective Equipment 500
23/54
Lincoln make DC600 power source with LN25
wire feeder and magnum 200/400amps welding
torches.
Fronius make synergic 5000cc with VR400S
wire feeder and torch assembly.
1.2mm flux cored wire is used in both wire
feeders for better control of weld metal.
Piped CO2 gas facility available in all four
shops.
LIMITATIONS AT SITE WELDING-
Additional protection for shielding gas from
heavy windows.
Transportation of additional CO2 cylinders.
Scaffolding arrangement for wire feeder at
elevations.
Not suitable for thickness less than 12.7mm
and pipe size less than 10 inch dia.
Spacing of joint with adjacent pipe at rack.
-
8/7/2019 Personal Protective Equipment 500
24/54
FUNDAMENTALS OF NDT
-
8/7/2019 Personal Protective Equipment 500
25/54
Nondestructive testing (NDT) is a wide group of
analysis techniques used in science and industryto evaluate the properties of a material,component or system without causing damage.The terms Nondestructive examination (NDE),Nondestructive inspection (NDI), andNondestructive evaluation (NDE) are alsocommonly used to describe this technology.Because NDT does not permanently alter thearticle being inspected, it is a highly-valuabletechnique that can save both money and time inproduct evaluation, troubleshooting, and research.Common NDT methods include ultrasonic,magnetic-particle, liquid penetrant, radiographic,remote visual inspection (RVI), eddy-currenttesting, andlow coherence interferometry. NDT isa commonly-used tool in forensic engineering,mechanical engineering, electrical engineering,
civil engineering, systems engineering,aeronautical engineering, medicine, andart.
S cope-
NDT method are used to detectsurface,subsurfaces and internaldiscontinuities in the materials and give
quality control checks in various stages ofmanufacturing
ASME sec-V IS the relevant code for thevariouss NDT methods used in industries.
PROGRAM OBJECTIVE -
http://en.wikipedia.org/wiki/Ultrasonic_testinghttp://en.wikipedia.org/wiki/Magnetic-particle_inspectionhttp://en.wikipedia.org/wiki/Liquid_penetrant_testinghttp://en.wikipedia.org/wiki/Radiographic_testinghttp://en.wikipedia.org/wiki/Eddy-current_testinghttp://en.wikipedia.org/wiki/Eddy-current_testinghttp://en.wikipedia.org/wiki/Optical_interferometryhttp://en.wikipedia.org/wiki/Forensic_engineeringhttp://en.wikipedia.org/wiki/Mechanical_engineeringhttp://en.wikipedia.org/wiki/Electrical_engineeringhttp://en.wikipedia.org/wiki/Civil_engineeringhttp://en.wikipedia.org/wiki/Systems_engineeringhttp://en.wikipedia.org/wiki/Aeronautical_engineeringhttp://en.wikipedia.org/wiki/Medicinehttp://en.wikipedia.org/wiki/Arthttp://en.wikipedia.org/wiki/Ultrasonic_testinghttp://en.wikipedia.org/wiki/Magnetic-particle_inspectionhttp://en.wikipedia.org/wiki/Liquid_penetrant_testinghttp://en.wikipedia.org/wiki/Radiographic_testinghttp://en.wikipedia.org/wiki/Eddy-current_testinghttp://en.wikipedia.org/wiki/Eddy-current_testinghttp://en.wikipedia.org/wiki/Optical_interferometryhttp://en.wikipedia.org/wiki/Forensic_engineeringhttp://en.wikipedia.org/wiki/Mechanical_engineeringhttp://en.wikipedia.org/wiki/Electrical_engineeringhttp://en.wikipedia.org/wiki/Civil_engineeringhttp://en.wikipedia.org/wiki/Systems_engineeringhttp://en.wikipedia.org/wiki/Aeronautical_engineeringhttp://en.wikipedia.org/wiki/Medicinehttp://en.wikipedia.org/wiki/Art -
8/7/2019 Personal Protective Equipment 500
26/54
To bring the awareness of various NDTmethods ,their applications ,advantages andlimitations.
To share our field experience and discuss case
studies to high light the importance of NDT.
BRIEF DESCRIPTION OF NDT -
Various NDT methods are used in theindustries for the various purpose at different
stages. The mechanism of each method varies and is
based on the scientific principles,they arebased on the application of sound energy,electrical energy,mechanical energy,magneticenergy etc.photo graphic principle of lightenergy is also used.
Each method has its own advantage and
limitation. They are used in various fields like medical
field ,ENGG. INDUSTRIES and also in day to daylife.
Sonography is used to check the sex of unbornchild.
X-ray are use in the airport to check theluggage of the passenger.
MT,UT&PT ARE USED IN INDUSTRIES.
APPLICATION-
DEFECT DETECTION-type,size&location ofdefects
-
8/7/2019 Personal Protective Equipment 500
27/54
CHECKING OF VARIOUS PROPERTIES-density,chemical composition,electrical andthermal conductivity.
Sorting out mix up of material-composition,grain size,chemicalcomposition&heat treatment cond.
DIMENSIONAL GAUGING-materialthickness&coating/plating thickness check.
IN SGIL we use NDT methods mostly for defectdetection and thickness checking of thepipes,plates,forgings castings and welding.
SELECTION OF NDT METHOD
Selection of NDT method to check the quality ofproduct is based on the following information-
Type & location of the defect.
Nature of the defect.
Expected orientation of the defect.
Surface condition.
Applicable codes&standards.(ASME,BS,IS,DINetc.)
Quantity of materials and facilities of NDTmethod.
Inspection at site or at workshop. Accessibility for the site inspection.
Environmental condition.
NDT instrumental availability.
Cost&time reqd.
-
8/7/2019 Personal Protective Equipment 500
28/54
VISUAL TESTING -
Visual testing is the oldest and simple NDTmethod and most commonly used
everywhere.it is used to detect surface defectslike laps,cracks,blow holes and many otherdefects which are visible to nakedeyes.nowadays sophisticated instruments likeboroscope,fibroscope,magnifying lensesetc,are used.
REQUIREMENT FOR TESTING -
Natural light/light source
Safe scaffolding
Personal safety equipments
Surface temperature with in 10 to 300c The surface for visual testing shall be free from
loose scale,paint and discontinuities such as pitsor gauges,weld spatter,dirt or other foreignmatter which affect examination results.
MAGNETIC PARTICLE TESTING -
The magnetism is induced in the part byelectricity or by using permanent magnetresulting the flow of lines of magnetic fluxin the part.
The magnetic lines of forces which pas
through the component are breaking dueto discontinuity in the material.
These broken lines are checked by usingiron powder forming the defectbindicationson the surface at the area wherediscontinuities are present.
-
8/7/2019 Personal Protective Equipment 500
29/54
MT is applicable to ferromagnetic materialonly.
It is applicable for the detection ofsurfaces and sub surface discontinuitiesonly.
MAGNETIC PARTICLE TEST-
MAGNETIC PARTICLE TEST KIT WITH MAGNETIC FIELD INDICATOR
MAGNETIC PARTICLE TESTING-
-
8/7/2019 Personal Protective Equipment 500
30/54
ABOVE FIGURE MENTIONED MAGNETIC PARTICLE TESTING
LIQUID PENETRANT TESTING-
PROCEDURE-
Clean the surface area to be tested.
Apply penetrant by brushing or spraying;wait for 7 to15 mins.
Remove excess penetrant by wiping with lint free
cloth.
Apply developer &wait for 15 minutes
Inspection and evaluation of the defects.
Cleaning to be done with free cloth only.
LIMITATION-
-
8/7/2019 Personal Protective Equipment 500
31/54
Surface temperature with in 10 to 52c.
Smooth surface is required.
Porous material can not be tested.
REQUIREMENT FOR TESTING-
Natural light/light source.
Safe scaffolding.
Personal safety equipments.
Surface temperature with in 10 to 52c.
The surface for liquid penetrant testing shall be free from
loose scale ,paint and discontinuities such as pits or
gouges,weld spatter,dirt or other foreign matter which
affect examination results.
The surface preparation can be carried out by grinding.
The purpose of surface preparation is-
-to avoid masking indication on te job surface
-to remove excess penetrant by wiping facilitate on
job surface
figure mentioned liquid penetrant testing.
-
8/7/2019 Personal Protective Equipment 500
32/54
THE FIGURE MENTIONED BELOW IS LIQUID
PENETRATION TESTING KIT WITH
CLEANER,PENETRANT&DEVELOPER-
ULTRA SONIC TESTING-
Ultrasonic sound waves are generated by using
electrical transducer.these waves are transmitted in thematerial by using couplant.the sound waves are flowing
inside the material and are distributed by the presence
of discontinuities in the material.The path of sound
waves and its disturbance is monitored on the CRT
screen.the loss of sound energy is indicated on the
screen which gives the idea about the defects ,its
size&location.
REQUIREMENT
NATURAL LIGHT/LIGHT SOURCE
SAFE SCAFFOLDING
PERSONAL SAFETY EQUIPMENTS
-
8/7/2019 Personal Protective Equipment 500
33/54
SURFACE TEMP. WITH 10 TO 52C
SURFACE FOR UT SHALL BE UNIFORM AND FREE
FROM LOOSE SCALE,PAINT AND AND
DISCONTINUITIES SUCH AS PITS,WELDSPATTER,DIRT OR OTHER FOREIGN MATTER WHICH
AFFECT EXAMINATION RESULTS
SURFACE PREPARATION CAN BE CARRIED OUT BY
GRINDING.
PURPOSE OF SURFACE PREPARATION-
-TO HAVE BETTER CONTACT AND TO FACILITATE
BETTER CONTACT OF
PROBE ON JOB SURFACE
SURFACE PREPARATION FOR
TESTING-
DIFFERENT TYPES OF SURFACE PREPARATIONS
ARE REQUIRED FOR PIPING
,NOZZLE&STRUCTURAL JOBS AS UNDER.
PIPE TO PIPE JOINT.
IN THIS TYPE OF JOINT,SURFACE TO BE
PREPARED FOR LONGITUDINAL SCANNING ON
THE PIPE SURFACE.TE SCANNING ZONE OR
SKIP DISTANCE REQUIRED IS 250MM ON BOTH
SIDES OF THE JOINT.SCANNING ZONE SHALL BE
FREE FROM WELD SPATTER,CLEAT MARK ETC.
ALSO SURFACE NEEDS TO BE PREPARED FOR
CIRCUMFERENTIAL SCANNING.HERE SCANNING
IS CARRIED OUT FROM TOP OF THE JOINT.SO
RIPPLES OF THE WELD JOINT SHALL BE
-
8/7/2019 Personal Protective Equipment 500
34/54
GROUND FLAT TO HAVE A PROPER SEATING OF
THE MINIATURE PROBE MOUNTED ON SHOE ON
THE WELD JOINT.AFTER GRINDING,THE
GRINDING MARKS SHALL BE SMOOTHEN BY
LIGHT FILLING WITH ROUND FILE.
ULTRA SONIC TESTING
-
8/7/2019 Personal Protective Equipment 500
35/54
ULTRASONIC TESTING TRANSDUCER
-
8/7/2019 Personal Protective Equipment 500
36/54
(PHASED ARRAY ULTRASONIC TESTING)
TOFD CONFIGURATION-
RADIOGRAPHY TESTING-
Radiography testing depends upon the ability of x-rays or
gamma rays to penetrate the test material.during
penetration the rays are partially absorbed by the
material.The amount of absorption depends upon the
density and thickness of the material.Defective areas do
not absorb the radiation energy.
Difference in radiation energy due to the presence of
discontinuity is recorded on a photographic film.
REQUIREMENT OF TESTING-
Safe scaffolding.
-
8/7/2019 Personal Protective Equipment 500
37/54
Safe work permit.
Surface temp. with in 10to52c
Thickness and diameter
Material
The surface for testing shall be free from loose scale
and ,discontinuous such as pits or gouges,weld
spatter,other foreign matter which affect examination
results.
The surface preparation can be carried out by
grinding.the purpose of the surface preparation is toavoid masking indication.
RADIOGRAPHY TESTING INSTRUMENT
LEAK TESTING-
The ability to find out the leakages using air/gas
medium at pressure or at vaccum.
The air or gas is filled in the vessel/tank at the
required pressure and temperature.the leakage
is detected by the loss of pressure checked by
pressure gauge.
Some times soaps solution is also used which
forms air bubbles at the area of leakage.
-
8/7/2019 Personal Protective Equipment 500
38/54
The surface for testing shall be free from loose
scale,paint and discontinuities such as pits or
gouges,weld spatter,dirt or other foreign matter
which affect examination results.
The surface preparation can be carried out by
grinding
EDDY CURRENT TESTING
This method is used for various applications such
as mixed metal sorting,dimensions
gauging,detection of defect ,measuring electrical
conductivity etc.
Principle of eddy currents is based on the
generation of induced current in the material and
monitoring on the screen.
-
8/7/2019 Personal Protective Equipment 500
39/54
PWHT
PROGRAM OBJECTIVE-
To refresh and update latest developments on
the post weld heat treatment(PWHT) &hydrotesting for engineers joining from other areas.
To identify the role and responsibilities of
concerned discipline engineers while handling
the PWHT ,heat treatment&hydrotesting process.
-
8/7/2019 Personal Protective Equipment 500
40/54
Program contents-
Fundamentals,process and monitoring of-
Preheat
Post heating
PWHT
Hydro testing
Purpose-
Purpose of this procedure is to define the equipmentsand methods to be followed for the preheat,postheat
&PWHT.
PWHT is carried out based on
Material composition
Thickness of weldment
Process requirement
PRE HEATING AND POST HEATING ARE CARRIED OUT
TO REDUCE COOLING RATES OF DEPOSITED WELD
METAL &HAZ FROM FUSION TEMPERATURE
TO REMOVE MOISTURE PRIOR TO START OF
WELDING WHICH PRODUCES HYDROGEN IN
PRESENCE OF ELECTRIC ARC.
REQUIREMENT OF PRE&POST HEATING-
For preheating,the weld joint shall be preheated
at or above the min. temperature in all direction
-
8/7/2019 Personal Protective Equipment 500
41/54
from the point of welding for a distance of 3 or
1.5 times base metal thickness.
In case of welding of two different p no.
materials,the min. preheat temperature shall behigher temperature for the materials to be
welded
When welding two different thickness,oreheat
temperature shall be the higher temperature for
the material to be welded
When welding two different thickness,preheat
temperature shall be the greater of the nominalthickness at the weld.
Preheating shall cover all types of welds
including permanent welds,tack welds,temporary
attachments,repair welds,seal welds of threaded
joints as applicable.
METHODS OF PRE-HEATING-
For CS/LTCS ,preheating may be carried out by
flame heating or electrical heating.
For low alloy steel ,piping materials above 2NB
pre heating shall be carried out by electrical
heating only.
PREHEATING IN CASE OF
INTERRUPTION IN WELDING
-
8/7/2019 Personal Protective Equipment 500
42/54
After welding is commenced,preheat shall be
maintained till PWHT is performed on P number
3,4,5a,5b&6 except all the following conditions are
satisfied-
At least 9.5mkm thickness of welding is
deposited or 25% groove is filled.
For p-3,4,5A(cr3%)&P-6,the weld is subjected to an
adequate intermediate heat treatment with a
controlled rate of cooling
After cooling &before welding is resumed ,visual
examination of the weld is performed to assure
that no crack have developed
Preheat to be applied,before welding resumes.
POST HEATING-
For low alloy steels,post heating shall be carried
out a temperature specified in applicable WPS
For elec. Heating,same arrangements are
specified in PWHT shall be followed.
The method of post heating shall be as follows
-for joints 2 and below size,post heating time shall be 10 min. forother cases post heating time shall be 30minutes
-for low alloy steel material post heating shall be carried out by electric
heating for joints above2
-preheat temperature shall be continuously maintained till start of
PWHT wherever specified in the codes/specifications.
METHODS OF PWHT-
-
8/7/2019 Personal Protective Equipment 500
43/54
Furnace heat treatment-for fabricated
equipments,piping&spools in mass.
Local heat treatment-for local joint of piping spool.
Flexible ceramic pads/induction coil
Combustion burner-gas fired-for fabrication
equipments
SURFACE PREPARATION-
The area to be covered for preheat ,post heat and PWHT
shall be free from paint,grease,tacks,spatters to avoid
damage due to short circuiting.
JOB KNOWLEDGR OF OPERATOR-
PWHT technician shall be capable of executing the
activity.this shall be assessed by QMD REPRESENTATIVE
PWHT(POST WELD HEAT TREATMENT)-
THIS IS THE PROCESS OF GRADUALLY AND UNIFORMLY
RAISING THE TEMPERATURE OF THE WELDMEENT AND BASE
METAL UP TO A CERTAIN TEMPERATURE ,HOLDING
SUFFICIENT TIME AT THAT TEMPERATURE AND THEN
GRADUALLY AND UNIFORMLY COOLING IT TO ROOM
TEMPERATURE.
POST WELD HEAT TREATMENT IS REQUIRED TO BE CARRIED
OUT ON WELDMENT,AS AND WHEN CALLED FOR BY
CODES/STANDARD/SPECIFICATION.THE PURPOSE OF PWHT
MAY BE EITHER OR ALONG THE FOLLOWING REASONS-
TO DISTRIBUTE THE AMOUNT OF RESIDUAL THERMAL
STRESSES PRODUCED DURING WELDING.
TO INCREASE RESISTANCE TO STRESS CORROSION.
-
8/7/2019 Personal Protective Equipment 500
44/54
TO IMPROVE DIMENSIONAL STABILITY AND DUCTILITY.
TO TEMPER THE HARD MATENSITIES AS AND WHEN FORM
DURINGWELDING.
PWHT TEMPERATURE-
For heating and cooling rate,the requirement
of WPS shall be strictly followed.
Soaking/holding time &temperature-for PWHT
soaking time&temperature requirement of
WPS shall be strictly followed.
Equipment for PWHT
Control panels
Heating elements
Thermocouple
Compensating leads
Temperature recorder
Thermal insulation
Attachment unit
Earthing cable
CERTIFICATION OF CONTROL
PANELS- All equipments are purpose built.
Electric power sources are 440v,3phase primary
supply or 220v single phase with either single
phase secondary output or step down
-
8/7/2019 Personal Protective Equipment 500
45/54
transformer secondary output giving low voltage
circuits.
Temperature control equipment is either
manually operated through energy regulators or
automated
All control panels are duly certified by P&M
before utilization in job to meet the requirement
as above and as per standards.
Heating elements-
Wherever induction heating is followed for
PWHT,the heating element shall be Ni-chrome
wire covered with ceramic beads/heating
pads/flexible ceramic pads.
Heating element position-
Welds shall have a circumferential band of
heating coil around the entire component
with the weld located in center.
Heating elements shall be fixed on
weldments by means of black annealed
iron wire.
The width of the heating band shall be as
follows,
For girth welds,the width of the heating
band shall be at least three times the wall
thickness at the weld of the thickest part
being joined and shall be maintained on
either side of the joint.
For nozzle and attachment welds,the
width of the band shall extend beyond the
-
8/7/2019 Personal Protective Equipment 500
46/54
nozzle weld or attachment weld on each
side at least two times the header
thickness and shall extend completely
around the header.
(ABOVE IMAGE SHOWING PWHT
PROCESSES)
-
8/7/2019 Personal Protective Equipment 500
47/54
THERMOCOUPLES-
Material shall be the ktype i.e. Nickel Chromium
/Nickel-Aluminium type
Compensating coil&thermocouple shall be caliberated
together.
The distance between two T C wires shall be min
6mm.
Insulation shall be removed from the end of the TC
WIRE shall not be more than 15mm.
Connect the positive/negative side of the TC with
respective positive/negative side of compensation
cable.
Thermocouple attachment shall be attached to the
work piece by direct wire capacity discharge method
or by nut and bolt connection.
If the nut and bolt connection method Is used,the
materials of nut-bolt shall be of compatible
composition with parent metal.
-
8/7/2019 Personal Protective Equipment 500
48/54
capacity discharge method
tack welds
Number of thermocouples-
1. Minimum no. of thermocouple is one one per
heating coil.However in addition to that the
following min. no. of thermocouples shall be used
for pipe welds.
-
8/7/2019 Personal Protective Equipment 500
49/54
2. Minimum requirement for number and location of
thermocouples are-
1 no. upto and inclusive of 6NPS
For 2and below,wherever joints are there within
the range of 100mm distance,one thermocouple
is permitted
2 numbers at 180degree for above 6 and up to
12 NPS inclusive.
3 numbers at 120degree for above 12NPS
For socket welds,I T C with in 100MM betweentwo joints.
But in all case minimum two layers of insulation with
minimum thickness of 50mm shall be used.open ends
to pipe and fittings shall be blanked to avoid through
draught cooling during cycle.
Verification-
For PWHT,after fixing the heating coils and the
thermocouples with proper connections with
recorder,the arrangement shall be certified by the
authorized representative of REAL QMD who shall
sign on the graph to indicate that the arrangement
are certified.Then the insulation shall be applied on
the heating coils.Again after attaining 300degree
Celsius during heating,the graph shall be recertified
by REAL QMD representatives.This requirement
shall be treated as mandatory for the acceptance of
post heating as well as for PWHT CYCLE except for
nitrogen purged/digital recorder.
During PWHT cycle front door of recorder shall be
kept in closed condition
-
8/7/2019 Personal Protective Equipment 500
50/54
Interrupted PWHT-
Due to power loss,equipment failure &due to
weather condition/permit problem,there may be
an interruption in heat treatment cycle-
If interruption occurs during heating
period,the cycle can be continued from the
fallen temperature.
If interruption occurs during soaking
period ,then the soaking temperature shall
be re-estabilished from the fallen
temperature at a rate no greater than thatspecified in code/estabilished welding
procedure and the soaking cycle shall be
repeated.
If interruption occur during cooling period
where controlled cooling is required,then
the complete PWHT cycle shall be repeated.
LOCATION OFTHERMOCOUPLES-
Thermocouples shall be fixed within the
area of heating band.Additional
thermocouples may be fixed as per
requirement to confirm hot zone or
gradient limitations,if necessary.
Thermocouple and their position shall
be identified on the relevant
temperature recording chart by number
or color/symbol of stamp.
-
8/7/2019 Personal Protective Equipment 500
51/54
Thermocouples requirement for branch
connection and pad shall be in line with
the requirement as mentioned in above
Thermocouples tack welded with pipeshall be removed completely after
PWHT and area to be DP tested
CALIBERATION OF
TEMPERATURE RECORDERS-
It shall be of the potentiometer ,
self compensating type havingchart feed recording.
Recorders shall be caliberated in
every 6months and caliberation
stickers shall be affixed to the
recorders
In addition, recorders shall be re-
caliberated after every repair andalso for the cases where there is
reason to believe that they are in
error.
And also to be verified for chart
speed is set to appropriate
speed,temperature recording
system is recording all
thermocouples and providinginformation on temperature
differences and trends during the
heating/cooling cycle
-
8/7/2019 Personal Protective Equipment 500
52/54
Caliberation certificates shall be
available at site.
THERMAL INSULATION-
The insulation shall be extended to a
minimum distance of 3 times the
heating bandwidth.The no. of layers and
extent of insulated area depends on-
1. Wall thickness
2. Pipe or fitting diameter
3. Gradient requirements&
4. Site condition
RECORDS-
Prior to starting the electrical
heating,the following information shallbe hand written on the recorder chart
by the technician.Date ,ISO
Nos,Agencys Name,Weld joint
details&Chart no.-the chart shall be
identified with ZXXX XXX /XXXX XXX
Z indicates JERP
1st
3 digits indicate unit no. innumeric
2nd3 digits alphabetic for the name
of immediate contractor.
-
8/7/2019 Personal Protective Equipment 500
53/54
3rd four digits indicate name of the
sub contractor
4th four digits indicates sequential
numbering of the chart e.g.Z312 RCC /HRIS 0001
Record of PWHT shall be
maintained in the format
2 QM 00 FMT ME 138
CHECKLIST FOR THE
STRESS RELIEVING UNIT- Check for the condition of power
cable
Check for the proper size of the
cable
Check for glanding for all cables
Check for lugging for all cables
Check for tightness for all
connection
Check for sealing of all un used
entry
-
8/7/2019 Personal Protective Equipment 500
54/54
top related