Why is post-weld heat treatment (stress relieving) sometimes
necessary for welded vessels?Ans: During the welding process, the
two metal pieces being joined are subject to extreme temperatures
and can cause the crystalline structure of the metal to pass
through various metallurgical phases. As a result, hardening (and
embrittlement) of the metal can occur to varying degrees (usually
dependent on carbon content). Heat treatment is designed to reduce
the hardness in the heat-affected zone of the metals and increase
ductility in these sections. Various pressure vessel codes contain
the specifics regarding the procedures for post-weld heat
treatment. Heat is usually held for one hour per inch of thickness
of the metal. The temperature used is based on the "P-number" of
the metals. P-numbers are assigned based on the chemical
composition of the metals. Holding temperatures can range from
1100-1350 F (593-732 C).3. What is the method of determining
maximum differential pressure during hydro testing of shell and
tube heat exchangers?Ans: Heat ex changers have two sets of test
pressures per side, one for strength tests, and the other for
"operating" or "leak" tests. The strength tests are set by the
design code and if you have the original design data sheets for
your equipment then the information should be shown on these. If
you do not then you will have to do the calculations yourself, the
exact method will depend upon which design code you use, the most
common one being TEMA (which uses the ANSI/ASME pressure vessel
code for reference in this area).Most shell and tube ex changers
are designed such that each side of the unit will withstand the
full design pressure, with only atmospheric pressure on the other
side. In order to save money, some larger units will have the
tube-sheets especially designed to withstand only a much lower
differential pressure (requiring both sides to be tested
simultaneously). This important information should be shall quite
clearly on the design sheets and on the vessel nameplate (assuming
that either are available). If the only need is to check that a
gasket has been properly installed then it can be permissible to
perform a lower pressure test based on the operating pressure. The
acceptability of this lower pressure test will often depend upon
the consequences of a leak.
Explain bending moment?Differentiate between a shaper machine
and a planner machineExplain the importance of Thermodynamics in
the field of Mechanical Engineering?What is the nomenclature of a
6203-ZZ bearing?Give the full form of SCADA, DCS and HMI.How does
the failing of Knuckle pin occur?What is the heat rate of a power
plant?Which of these have a higher efficiency: Diesel engines or
Petrol engines?What are the points in the stress/strain curve for
steel?What is ductile-brittle transition temperature?Differentiate
between Relay and Conductor?Differentiate between shaper and
planner?What is the immediate superclass of Menu?State the laws of
conservation of energy.What is a gear box and what are its
applications?What is Carnot engine?Which formula forms a link
between thermodynamics and electrochemistry?How will you calculate
the tonnage of Mechanical Press?What is maximum continuous
rating?What is the difference between Critical speed and Whirling
speed?What is plant load factor?What is hard material cast iron or
mild steel?How would you find the amount of natural gas required to
produce 1 KWhr of energy?What is annealing?How do you measure
temperature in a web bulb thermometer?What is the purpose of
governor in automobile?What is bearing stress?What is the
difference between SCADA and BMS?Explain Otto cycle.What is the
efficiency of v-type four stroke diesel engines?Is the boiler a
closed system?How many joules are there in one BTU?How many laws of
Thermodynamics are there?What is the consequence of not maintaining
hydrogen (or air) pressure in generator casing at a value above
atmosphericpressure when seal oil system is in service?Explain the
effect on the basis of which the cricket ball swings.What is the
method for testing Light Emitting Diode?What is the function of EGR
value? In a heat exchanger, if I have given pressure on tube side,
can I perform hydro test of shell side simultaneously? Why?Which is
the hardest compound known?What is gear ratio?Define torque.What is
PS?What is the mechanical advantage of a double pulley?What is Hess
law?How to control temperature (Electronics method)?What is a
Newtonian fluid?What is the significance of Torque (in N-m) given
in the engine specification?How to make operations by pressing a
single push button (at least for 2 operations)?What are the
materials used for sliding wear pad?Explain the second law of
thermodynamics.What is the difference between a gas turbine and a
steam turbine?What is knurling?What is OEE?Define Reynolds
number.What is the difference between a blower and a fan? What is
extruded Aluminum?
We would like to seek opinion of other memebers on the subject
of Hydro testing of shell and tube type heat exchangers/coolers.
The question is which side to be tested inorder to find out if a
tube is leaking or thinned out and is to be plugged before taking
the HE into operation. . Take one pariticular HE with high tube
side pressure and low shell side pressure such as gas coolers. Tube
side pressure could be between 10 -60 barG or even higher whereas
shell side is only 4-7 barG ( cooling water pressure). In order to
test such exchanger what we do is pressurize the tube side to its
required test pressure that is 1.5 times design. check for any
pressure drop. If no pressure drop, it is assumed that no tube is
leaking. If there is a pressure drop, it is assumed that there is a
tube leakage. The next step is how to identify the leaking tube.
For this purpose we pressurize shell side with utility air (
5-7barG) and then identify the leaking tube with soap solution
test. The above test is done if the bundle was mecahnically cleaned
with HP jet cleaning. In case a HE is identified as already leaking
in operation then the above procedure is reversed. That is first
the leaking tube is identified /plugged and after making sure all
leaking tubes have been identified and plugged then the tube side
is pressurized to desired test pressure. It may so happen that
again there is a pressure drop. The whole exercise has to repeated
once again. The question is at what pressure difference between the
shell side and tube side one must go for tube side ( higher
pressure ) testing. We have fixed about 10 barG as an arbitrary
figure. If the difference between the shell side and tube side is
less than 10 barG we test only shell side and assume that tube
bundle integrity is ensured. And if the difference of pressure is
more than 10 barG , we go for tube side testing as mentioned above.
Is this procedure technically acceptable? We have been doing so for
the last 20 years with very few cases of missing the target. Most
of the time the testing was reliable that is no tube leaked after
taking the HE in operation.
ON HYDROSTATIC TESTING HEAT EXCHANGERSINTRODUCTIONSection VIII
Division 1 of The ASME Boiler and Pressure Vessel Code
(Code)[i]requires testing the integrity of pressure vessels by
subjecting them to a hydrostatic pressure test of 1.3 times the
maximum allowable working pressure (MAWP) corrected for the
difference between allowable stress at the test temperature and the
design temperature.The Code provides for testing at higher
hydrostatic test pressures but most pressure tests are at the 1.3
multiple.For shell-and-tube heat exchangers built to the
TEMAStandards,Paragraph RCB-1.31 Standard Test,the holding period
is at least 30 minutes[ii]. The TEMA Standards require testing the
shell and tube sides separately in such a manner that leaks at the
tube joints can be detected at least from one side.
The Code does not permit any visible leakage through the joints
during the Authorized Inspectors (AIs) examination during and after
the holding period on hydrostatic test pressure.Paragraph UG-99(g)
states in part, Following the application of the hydrostatic test
pressure, an inspection shall be made of all joints and
connections.This inspection shall be made at a pressure not less
than the test pressure divided by 1.3.Except for leakage that might
occur at temporary test closures for those openings intended for
welded connections,leakage is not allowed at the time of the
required visual inspection.(Italics added.)
This means that the AI must reject any visible leakage of
exposed tube-to-tubesheet joints such as weeping around the
tube-to-tubesheet connections during testing. Inspection is with
the shell side of the exchanger under the hydrostatic test pressure
divided by 1.3 and the tube side at atmospheric pressure with the
tube-to-tubesheet joints visible.
Tube-to-tubesheet joints of some types of shell-and-tube heat
exchangers, such as fixed tubesheet designs and closed feedwater
heaters in which the channel is welded to the shell, are visible
only from the channel side with the shell side under pressure and
the channel side at atmospheric pressure.
The ASME Codes Paragraph U-99(g) states, The visual inspection
of joints and connections for leaks at the test pressure divided by
1.3 may be waived: provided (1) a suitable gas leak test is
applied; (2) substitution of the gas leak test is by agreement
reached between the Manufacturer and Inspector; (3) all welded
seams which will be hidden by assembly be given a visual
examinations for workmanship prior to assembly; and(4) the vessel
does not contain a lethal substance. This is particularly pertinent
for heat exchangers in lethal service because literal
interpretation of the waiver would preclude using fixed tubesheet
exchangers for lethal service applications. But many such
exchangers have been Code stamped and this practice continues
throughout the industry.
Users and designers should be aware that the purpose of the
Codes standard hydrostatic test described in Paragraph UG-99 is to
test the capacity of the vessel to withstand the design pressure;
it is not to determine whether the tube-to-tubesheet joints are
sufficiently leak tight to prevent leakage of process fluids with
low viscosities through the joints.(Leak rates vary inversely with
fluid viscosity.)Users must recognize the hazards of process fluids
leaking from the channel into the shell and where hazards exist,
specify further leak testing as described in Section V of the Code.
This includes the possibility of wiredrawing (wormholing) in high
pressure closed feedwater heaters in which a leak of high pressure
feedwater through the tube-to-tubesheet welds can erode the steel
under the weld overlay to which the tubes are welded. Severe
wormholing can shorten feedwater heater life.
Current practice is for Manufacturers to use loss of pressure in
the channel to determine whether there is leakage from the channel
side to the shell side when the shell side is not visible for
inspection. However, the gradations on pressure test equipment in
common use are too coarse to indicate very small leaks or weeping.
It follows that users should specify that Manufacturers use other
methods to verify non-visible leakage when such leaks could be
hazardous or harmful during operation of the heat exchanger.See
Table 1 for typical test pressures and pressure gage
graduations.
Because the ASME Code rules and the API and TEMA Standards do
not require gas leak testing to verify that there are no-leaks from
the channel side to the shell side, Manufacturers will not perform
such tests unless the User or the Users Agent specifies that they
do so.Therefore, when they hydrostatically test the tube side, they
rely on pressure loss in the tubes and channel during the holding
period to indicate leakage through the tube-to-tubesheet joints.
The gages in widespread use in the heat exchanger and pressure
vessel industries for hydrostatic testing to meet the Code
requirements are dial type Bourdon tube gages.Some Manufacturers
use strip chart or circular recording gages but the graduations are
similar to those of dial gages.
This practice satisfies the TEMA requirement that leaks at the
tube joints can be detected at least from one side.API 660 also
accepts this practice[iii].Although gas leak testing is not onerous
and costly, heat exchanger manufacture is a very competitive
business and it is not likely that Manufacturers will perform
testing that the ASME Code does not require unless the procurement
specification requires it.
For constructions in which the Authorized Inspector cannot
visibly examine the shell sides of tubesheets, heat exchanger users
are cautioned that pressure loss to determine whether there are
leaks from the channel into the shell does not indicate weeping
through the tube-to-tubesheet joints because the gages in common
use are not sufficiently sensitive to indicate a pressure loss that
discloses such small leaks.This is especially so when the tube side
hydrostatic test pressure is substantially higher than that of the
shell side.
An analysisof the pressure testing processwhich hydrostatic test
water is appliedin the tubeside of an exchanger where the backside
of the tubesheet is not visible wasadapted from material previously
published on the MGT Inc. website.It demonstrates that relying on
gage indication of pressure loss to assess leaks (weeping) that
would not be visible during hydrostatic testing does not indicate
whether there are such small leaks.[iv]It shows that using test
gage pressure loss to determine if there is leakage through the
tube joints from the channel to the shell of heat exchangers in
which the back side of the tubesheet is not visible does not
disclose weeping leakage from the channel into the shell through
the tube-to-tubesheet joints.Such leakage does not comport with the
implication of the language of the Codes Paragraph U-2(g) that
leakage is not permitted.In this discussion weeping is defined as a
leak of 20 drops per hour or approximately 1 cm3(0.061 in3) which
if visible would be 10 drops of water on the tubesheet face after
the half-hour TEMA minimum holding period.
If the exchanger service is for a fluid less viscous than water
the likelihood of leakage in services may be very high if the
Manufacturer relies on changes in the pressure gage reading to
assess whether there is leakage from the channel side into the
shell during hydrostatic testing.
ISSUES ABOUT HYDROSTATIC TESTING HEAT EXCHANGERS
1. Should the User or the Users agent or a Manufacturer with
knowledge about the hazards of the service be required to specify
further leak testing and the kind of leak testing the Manufacturer
must use and whether the API-660 and TEMA Standards requirements
meet the Codes requirements?2. Despite the Code rules about the
unacceptability of leakage through the joints of pressure vessels
and heat exchangers, the TEMA and API standards do not require leak
testing every heat exchanger and Manufacturers will not perform
such leak tests unless Users request them. It is necessary to
understand the service of the exchanger and the degree of hazard
such leakage presents. when determining whether to require the
Manufacturer to perform leak tests.For example, a minor tube joint
leak in a water-to-water cooler presents no hazard, whereas leakage
of a volatile, flammable or explosive fluid could cause damage such
as wire drawing, injury or death.How should users deal with the
possibility of such leaks?3. What constitutes a suitable leak test
if the standard Code hydrostatic test cannot disclose very small
leaks (weeping)?4. Are only leak tests described in the Codes
Section V acceptable for meeting the Codes no-leak requirement?The
simplest and least costly additional test is gas-bubble testing
(often erroneously described as soap bubble testing.)Typically, the
Manufacturer pressurizes the shell with air or nitrogen at 30 to 50
psi and applies a commercial bubble former to the tube-to-tubesheet
joints.This is a very effective way to disclose leaking
tube-to-tubesheet joints.When the User or Users agent or
knowledgeable Manufacturer is aware of the potential hazard of a
leak in service, or when the channel side design pressure is
substantially higher than that of the shell side, it is reasonable
to specify halogen or helium sniffer leak testing to satisfy a
no-leak requirements.For tubes welded to the tubesheet and
subsequently expanded, the prudence suggests that in addition to
such leak testing the welds should be fluid penetrant examined.
When the channel side design pressure is very high in the order
of 1500 lb/in2and above - it is prudent to require cycle
testing.Typical procurement specifications for high-pressure
feedwater heaters require 10 cycles of bringing the channel to the
hydrostatic test pressure followed by dropping the pressure to
atmospheric for each cycle. (Figure 1) Such testing has beneficial
effects on the structure in addition to possibly cracking
subsurface porosity bubbles and disclosing cracks in the welds.For
such equipment small leaks of high-pressure feedwater through the
tube-to-tubesheet joints leads to wire drawing (wormholing), which
when severe can be extremely expensive to repair, especially when
considering the loss of cycle efficiency when the heater is
bypassed to allow access for repairs.Therefore, typical feedwater
heater procurement specifications require helium leak sniffer
testing (mass spectrometer) testing the tube-to-tubesheet joints
during manufacture.
COMMENTS AND RECOMMENDATIONS
1. The Code is a pressure containment safety code and the
hydrostatic test represents only a test adequate for the typical
heat exchanger not in a specific service where leakage is an
issue.Users should be aware of these facts.2. Loss of test gage
pressure during ASME Code required hydrostatic testing does not
disclose very small leakage (weeping) from the channel side to the
shell side because of the insensitivity of the test gages used
industry wide for hydrostatic testing.3. Users of the Code should
also be aware that, although the TEMA Standards require a minimum
of one-half hour hold time of hydrostatic pressure, the Code does
not specify a hold time, which would be important for detecting
leakage through welds and joints.Because hold time does not
guarantee that a joint is 100% free from leaks, Designers, Users,
and Manufacturers need to agree on the suitable test(s) for the
service conditions.4. Designers, Users, and Manufacturers should
agree on the definition of joint type and to the nondestructive
Tests (NDT) for all welded joints.5. Designers, Users and
Manufacturers of heat exchangers should consider the specific
language of the Codes no-leak requirement of UG-99(g) and the
differences between it and the requirements of API 660 and the TEMA
Standards.6. When preparing procurement specifications, Engineers
should consider the service of the exchanger and the UG-99(g)s
requirements and determine the appropriate leak tests for meeting
them.Users and Manufacturers should agree beforehand on the
suitable leak detection system when invoking the waiver provisions
of the Codes Paragraph UG- 99(2)(g).7. The language of the waiver
in UG-99(2)(g) needs clarification with respect to using fixed
tubesheet exchangers for lethal service, possibly with a specific
exception allowing their use with appropriate precautions.NDT
TECHNIQUESRadiographic Testing ProcedureThis content provides you
with a example Radiographic Testing Procedure. This is a general
and sample RT procedure and you need to modify it to meet your
project specifications.1. SCOPE:1.1-This Procedure describes the
general requirements for radiography examination (RT) according to
related approved weld map for the metallic welding and casting as
may be required by the specification or under which component is
being designed and manufactured.1.2-This radiographic testing
procedure provides the material, equipment, calibration, personnel
qualification, examination process, evaluation, records and
acceptance standards forXXXProject which will be fabricated in
YYY.2. SURFACE CONDITIONAccording to T.222.2, the weld ripples or
weld surface irregularities on the both the inside (where
accessible) and out side shall be removed by any suitable process
to such a degree that the resulting radiographic testing image due
to any surface irregularities cannot mask or be confused with the
image of any discontinuity. the finished surface of all butt welded
joints mat be flush with the base material or may have reasonably
uniform crowns, with reinforcement not to exceed that specified in
the referencing code section.3. RADIATION SOURCE3.1-
X-Radiation:The radiography testing techniques shall demonstrate
that the required radiography sensitivity has been obtained.
Maximum x-ray voltage is 300 KV.3.2- Gamma radiation:The
recommended minimum thickness for which Radio-active isotopes may
be used as follow:Table 3.2MaterialIridium192Cobalt 60
Steel0.75 in1.50 in
Copper or high nickel copper0.65 in1.30 in
Aluminum2.50 in--
The maximum thickness for the use of radioactive isotopes is
primarily dictated by exposure time, therefore; upper limits are
not shown. The minimum Recommended thickness limitation may be
reduced when the radiography techniques are used to demonstrate
that the required radiographic testing sensitivity have been
obtained, by purchaser approval.4. RADIGRAPHIC FILMSAny
commercially available industrial radiography films may be used in
accordance with SE 1815(ASTM) standard test method for film system
in industrial radiography. Radiography film shall be fine grain
high definition, high contrast film (Kodak type AA 400, FUJI 100 or
AGFA D7).5. SCREENSAny commercially available intensifying screen,
except those of the fluorescent type, may be used. Intensifying
screen for x-ray or Gama ray method dividedin two categories:
1-front screen 2-back screen. Commonly lead screens use with 27
micron thickness. (Front screen)6. PENETRAMETER
(I.Q.I)Penetrameters shall be either the whole type or the wire
type and shall be manufactured and identified in accordance with
the requirements or alternatives allowed in SE 142 or SE 1025 (for
whole type) and SE-747 (for wire type), and appending. ASME V 2007
ED & ASME Sec VIII Div I ED 2007.Penetrameters shall consist of
those in table 233.1 for hole type and those in table 233.2 for
wire type. (Wire type IQI shall be used for welds.)
7. SELECTION OF PENETRAMETER (I.Q.I)7.1.Material. IQIs shall be
selected from either the same alloy material group or grade as
identified inSE-1025, or SE-747, as applicable, or from an alloy
material Group or grade with less radiation absorption than the
material being radiographed.7.2Size. The designated hole IQI or
essential wire listed in Table T-276 provided an equivalent IQI
sensitivity is maintained. See T-283.2.shall be as specified in
Table T-276. A thinner or thicker hole-type IQI may be substituted
for any section thickness(a) Welds With Reinforcements. The
thickness on which the IQI is based is the nominal single-wall
thickness plus the estimated weld reinforcement not to exceed the
maximum permitted by the referencing Code Section. Backing ringsor
strips shall not be considered as part of the thickness in IQI
selection. The actual measurement of the weld reinforcement is not
required.(b) Welds Without Reinforcements. The thickness on which
the IQI is based is the nominal single-wall thickness. Backing
rings or strips shall not be considered as part of the weld
thickness in IQI selection.7.3 Welds Joining Dissimilar Materials
or Welds with Dissimilar Filler Metal.When the weld metal is of an
alloy group or grade that has a radiation attenuation that differs
from the base material, the IQI material selection shall be based
on the weld metal and be in accordance with T-276.1. When the
density limits of T-282.2 cannot be met with one IQI and the
exceptional density area is at the interface of the weld metal and
the base metal, the material selection for the additional IQIs
shall be based on the base material and is in accordance with
T-276.1
8. PLACEMENT OF RADIOGRAPHIC TESTING PENETRAMETER (I.Q.I)8.1-
Source side penetrameters:The penetrameters shall be placed on the
source side of the part being examined, except for the condition
described in chapter 8.2.8.2- film side
penetrameters:Sensitivity:The sensitivity required using wire type
IQI shall be 2%.Sensitivity:(Diameter of thinnest wire visible on
radiograph /Part thickness at IQI location)x 100 Where
inaccessibility prevents hand placing the penetrameter (s) on the
source side, it shall be placed on the film side in contact with
the part being examined. A lead letter F shall be placed adjacent
to or on the penetrameter (s).
9. NUMBER OF PENETRAMETER (I.Q.I)When one or more film holders
are used for an exposure, ate least one penetrameter imager shall
appear on each radiograph.If the requirements of T-282 are met by
using more than one penetrameter, one shall be representative of
the lightest area of interest and the other the darkest area of
interest.The intervening densities, on the radiograph, shall be
considered as having acceptable density.Number of I.Q.I shall be
according to ASME SEC V.T.277.2.10. RADIOGRAPHIC TESTING TECHNIQUEA
single-wall exposure technique shall be used for radiography
whenever practical. When it is not practical to use a single-wall
radiographic testing technique, a double-wall technique shall be
used. An adequate number of exposures shall be made to demonstrate
that the required coverage has been obtained.10.1 Single-Wall
Technique. In the single-wall radiographic testing technique, the
radiation passes through only one wall of the weld (material),
which is viewed for acceptance on the radiograph.
10.2 Double-Wall Technique. When it is not practical to use a
single-wall technique, one of the following double-wall techniques
shall be used.(a) Single-Wall Viewing. For materials and for welds
in components, a technique may be used in which the radiation
passes through two walls and only the weld (material) on the
film-side wall is viewed for acceptance on the radiograph. When
complete coverage is required for circumferential welds
(materials), a minimum of three exposures taken 120 deg to each
other shall be made.(b) Double-Wall Viewing. For materials and for
welds in components 312 in. (89 mm) or less in nominal outside
diameter, a technique may be used in which the radiation passes
through two walls and the weld (material) in both walls is viewed
for acceptance on the same radiograph .For double-wall viewing,
only a source-side IQI shall be used. Care should be exercised to
ensure that the required geometric unsharpness is not exceeded. If
the geometric unsharpness requirement cannot be met, then
single-wall viewing shall be used.(1) For welds, the radiation beam
may be offset from the plane of the weld at an angle sufficient to
separate the images of the source-side and film-side portions of
the weld so that there is no overlap of the areas to be
interpreted. When complete coverage is required, a minimum of two
exposures taken 90 deg to each other shall be made for each
joint.(2) As an alternative, the weld may be radio graphed with the
radiation beam positioned so that the images of both walls are
superimposed. When complete coverage is required, a minimum of
three exposures taken at either 60 deg or 120 deg to each other
shall be made for each joint.
11. SOURCE TO OBJECT AND OBJECT TO FILM DISTANCE (SOD &
OFD)According to geometric unsharpness formula (Ug = f *OFD/FOD)
for minimizing the Ug value, OFD value shall be minimizing
therefore object to film distance shall be minimum.Source to object
distance (SOD) shall be set according radiographic technique,
object shape and strength of source. 12. RADIOGRAPHIC TESTING
IDENTIFICATION SYSTEMThe method shall be used to produce permanent
identification to the radiographies traceable to the contract,
components, welds or weld seams, or part numbers, as appropriate.
This identification mark shall not obscure the area of interest.13.
RADIOGRAPHIC TESTING ACCEPTANCE STANDARDRefer to ASME Sec VIII,
Div. Ia) Butt welded joints surfaces shall be sufficiently free
from coarse ripples ,grooves , overlaps and abrupt ridges and
valleys to permit proper interpretation of radiographic and the
required non-destructive examinations.If there is a question
regarding the surface condition of the weld when interpreting a
radiographic film, the film shall be compared to the actual weld
surface for determination of acceptability.b) Indications shown on
the radiographies of welds and characterized as imperfections are
un-acceptable under the following condition:1) Any indications
characterized as a crack or zone of incomplete fusion or
penetration.2) Any other elongated indication at radiography, which
has length greater than:(a) 1/4 in. (6mm) for t up to 3/4 in.
(19mm)(b) 1/3 t for t from 3/4 in. (19mm) to 2 1/4 in. (57mm)(c)
3/4 t (19mm) for t over 2 1/4 in. (57mm)Where: t= thickness of weld
excluding any allowable reinforcement.3) Any group of aligned
indications that have an aggregate length greater than t in a
length of 12t , except when the distance between the successive
imperfections exceed 6L where L is the length of the longest
imperfection in the group.4) Rounded indications in excess of that
specified by the acceptance standards given in ASME sec. VIII, DIV
I, appendix 4 fig. 4-2 to 4-8Note: spot RT shall be done as per
ASME Sec. VIII, Div. 1 UW-52; however the acceptance criteria shall
be according to UW-51 (as specification). 14. DEFECT REMOVALRepair
area shall be located on the weld line after evaluation &
interpretation of radiograph .defects shall be removed by suitable
method such as grinding, chipping or gouging (if permitted).welding
of the repair area shall meet the requirement of related
WPS,PQR.15. CERTIFICATION AND PERSONNEL QUALIFICATION IN
RADIOGRAPHIC TESTING.Personnel performing radiography examination
to this procedure shall be qualified and certified by XXX also
shall meet the requirements of ASNT-SNT-TC-1A-2001 EDITION at least
level II and on ASNT-SNT-TC-IA for code section I and sec VII div
2. Film interpreter shall have level II as a minimum.
IMPORTANT
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