DefectTn giK hiuV trNguyn nhn gy raNtCrackCHnNt nguiCold
shutsSinh ra do thiu ht ca dng kim loi lng khi gp dng kim loi khc
hay gp kim loi rnNt dng saoCrater Cracksu mt ng hnDo trc trc v vic
hn thm ni dng que hn trc khi tt h quangNt dng vnh nnHat CracksKhong
qu na phn trn mi hnDo in p qu cao hoc tc hn qu thpNt cnh v chn mi
hnToe & Root cracksHnNt ng nng chyFusion line cracksHnNt di ng
hnUnderbead CrackHnh thnh trong vng nh hng nhitDo cng ti vng nh hng
nhit cao v co ko qu mcNt dng phn lpLamination TearingMi hn ch TDo
tm ngang ca mi hn T c hn c hai mt nn ng sut pht trin theo ng bin
nay.KhcOtherLm chnRoot Concavity/Internal concavityICTi chn mi hnDo
hn bng phng php FCAWTch lpLaminationDo rn v cn vt cNp gpSeamRn/cn
vt c c vt lm trn mtChng mp rnForging LapRn/cn vt c c vt li trn mtR
xForging BurtsTrong hoc b mt chi titDo rn nhit qu thpKhng thuLack
of penetrationLPTi chn mi hnKhe h ca y mi hn qu nh, dng in khng ,
tc hn nhanh, vt mp khng thch hpIncomplete penetration/Inadequate
penetration without High-lowIPKhe h ca y mi hn qu nh, dng in khng ,
tc hn nhanh, vt mp khng thch hpKhng thu do ghp lch hai tm kim
loiInadequate penetration due to high-lowIPDGhp lch hoc do g hai kt
cu khng cng chiu dyKhng nguLack of fusionLFNi cc lp kim lai tip gip
nhauKim lai khng t ti nng chy cn thit (Hn)Incomplete FusionIFKhng
ngu do chng lnhIncomplete Fusion due to cold lapIFDGia 2 lp hn hoc
gia kim loi hn v kim loi c bn (khng m ra ti b mtB mt tip gip ti mt
trong hai lp kim loi khng t nhit nng chy cn thitChy chn/Rnh
khuytUndercutUCKim loi hn khng a vo do dng in qu ln, chiu di h
quang khng ng mc, di chuyn in cc nhanhvv.Chy thngBurn- throughBTChn
mi hnHn dng in cao, tc di chuyn in cc chm.Lch mpHigh - LowGhp lch
hoc do g hai kt cu khng cng chiu dyRng y ng hnHollow BeadBc kh nm
ngm dc di y trung tm ng hnHnTp chtInclusionsX diElonggated slag
inclusionESIHn, cX nIsolated slag inclusionISIHn, cR kh nIndividual
or scattered porosityPHn, cCm r khCluster porosityCPTrong hoc b mt
mi hnHn, cNgm tungstenTungsten inclusionsTITrong mi hnhn TIGThin
tchSegregationMt hay nhiu nguyn t ca hp kim khng khuch tn u m tp
trung li mt vng no trong vt c
RTACCEPTANCE CRITERIA OF WELD (RT)According to ASME Sec. VIII,
Div 1 (UW-51, UW-52) (Pressure Vessels)No.Kind of
imperfectionUnacceptance1Crack (Nt)xx: Khng chp nhn2Lack of fusion
(khng ngu)x3Incomplete penetration (khng thu)x4Elongated Indication
(khuyt tt di)Length > 1/4" (6mm) for t 1/3t for 3/4" (19mm) <
t 9/4" (57mm)5Aligned Indications (cc khuyt tt c sp t theo
hng)Length of a group of aligned indications greater than t in a
length of 12t, except distance between the successive imperfections
exceeds 6L (L: the length of the longest imperfection in the
group)6Rounded Indication - Appendix 4 (nh Ga khuyt tt trn).Size of
random indication > t/4 or 5/32" (4mm) whichever is smaller.Kch
thc ln nht :t/4 hoc 4mm ty gi tr nh hn.Size of isolated indication
> t/3 or 1/4" (6 mm) for t 2" (51mm)Sum of diameters of the
aligned indications >= t in a length of 12t1.6002Length of the
cluster greater than 1" (25.4 mm) or 2tThe sum of the lengths of
the clusters > 1" (25mm) in a 6" (152mm) length weld where more
than one cluster is present.Notes:Rounded Indication: Indications
with a maximum length of three times the width or less on the
radiograph are defined as rounded indications. These indications
may be circular, elliptical, conical or irregular in shape and may
have tail. When evaluating the size of an indication, the tail
shall be included. The indication may be from any imperfection in
the weld, such as porosity, slag or tungsten.Aligned Indication: A
sequence of four or more rounded indications shall be considered to
be aligned when they touch a line parallel to the length of the
weld drawn through the center of the two outer rounded
indications.t - the thickness of weld excluding any allowable
reinforcement. For a butt weld joining two members having different
thickness at the weld, t is the thinner of these two thickness. If
a full penetration weld includes a fillet weld the thickness of the
throat of the fillet shall be included in t.ACCEPTANCE CRITERIA OF
WELD (RT)According to ASME B31.3 Table 341.3.2 (Process
Piping)No.Kind of imperfectionUnacceptance (Khng Chp nhn)( Loi
khuyt tt)Normal Fluild serviceSevere Cyclic Conditions1Crack
(nt)xx2Lack of fusion (khng ngu)xx3Incomplete penetration (khng
thu)Depth of IP>1/32in (1mm) and >0,2TwxCumulative length of
IP >1.5" (38mm) in any 6" (152mm) weld length4Internal porosity
(r kh trong)For Tw 1/4" (6mm), limit is same as App. 4 of ASME Sec.
VIII, Div.1Limit is same as App. 4 of ASME Sec. VIII, Div.1For Tw
> 1/4" (6mm), limit is 1,5 x limit in App. 4 of ASME Sec. VIII,
Div.15Slag inclusion, Tungsten inclusion,or elongated indication
(X, tungstel hoc khuyt tt di)individual length > 2Twindividual
length > Tw/3individual width > 1/8" (3mm) and >
Tw/2individual width > 3/32" (2,5 mm) and > Tw/3Cumulative
length > 4Tw in any 6" (150 mm) weld lengthCumulative length
> Tw in any 12Tw weld length6Undercutting (chy chn)Depth of UC
> 1/32" (1mm) and >Tw/4x7Surface porosity or exposed slag
inclusion (r kh hoc x b mt)xx8Concave root surface (lm chn)Total
joint thickness, incl. weld reinf., 1/16" (1,5 mm) for Tw3 mm for
6mm1" (25mm)Heigh of reinf. >3/16" (5 mm) for Tw>1"
(25mm)Notes:See Fig 341.3.2 for typical weld imperfections; Tw is
the nominal wall thickness of the thinner of two components joined
by a butt weld.Acceptance criteria for castings are specified in
para. 302.3.3ACCEPTANCE CRITERIA OF WELD (RT)According to ASME Sec.
IX, QW-191.2 (Welder Qualification)No.Kind of
imperfectionUnacceptanceRemark1Crack (nt)x2Lack of fusion (khng
ngu)x3Incomplete penetration (khng thu)x4Elongate Slag Inclusion(X
di)L>1/8"(3,2mm) for t 3/8" (10mm)L: length of the
imperfectionL>1/3t for (10mm) 3/8" < t 2.1/4" (57mm)L>
3/4" (19mm) for t > 2.1/4" (57mm)5Group of Slag inclusions in
line(Nhm x dng ng)L>t in a length of 12t, except the distance
between the successive imperfections exceeds 6L (L is the length of
the longest imperfection in the group)6Rounded indications
(porosity,slag/tungsten with the length three times the width or
less)- d>20%t or 1/8" (3,2mm) whichever is smallerd: dimension
of rounded indications- For welds in material less than 1/8"
(3,2mm) in thickness, number of rounded indications > 12 in a 6"
(152mm) in length of the weld. A proportionately fewer number of
rounded indications shall be permitted in welds < 6" (152mm) in
length.- For weld material thickness > 3.2 mm, refer to chart in
App.I. Rounded indications less than 1/32in. (0,8mm) in max.
diameter shall not be considered.ACCEPTANCE CRITERIA OF
WELDAccording to API 650, API 620No.Kind of
imperfectionUnacceptanceAcceptance standards shall be in accordance
with section VIII of the ASME CodeACCEPTANCE CRITERIA OF
WELDAccording to ASME B31.8 (GAS TRANSMISSION AND DISTRIBUTION
PIPING SYSTEMS)No.Kind of imperfectionUnacceptanceAcceptance
standards shall be in accordance with API 1104ACCEPTANCE CRITERIA
OF WELD (RT)According to ASME Sec. I (PW-51) (Power Boilers)No.Kind
of imperfectionUnacceptance1Crack (Nt)x2Lack of fusion (khng
ngu)x3Incomplete penetration (khng thu)x4Elongated Indication
(khuyt tt di)Length > 1/4" (6mm) for t 9/4" (57mm)5Aligned
Indications (cc khuyt tt c sp t theo hng)Length of a group of
aligned indications greater than t in a length of 12t, except
distance between the successive imperfections exceeds 6L (L: the
length of the longest imperfection in the group)6Rounded Indication
- Appendix A250 (Khuyt tt trn - xem ph lc A250)Size of random
indication > t/4 or 5/32" (4mm) whichever is smaller.Size of
isolated indication > t/3 or 1/4" (6 mm) for t 2" (51mm)Sum of
diameters of the aligned indications >= t in a length of
12tLength of the cluster greater than 1" (25.4 mm) or 2tThe sum of
the lengths of the clusters > 1" (25mm) in a 6" (152mm) length
of weld where more than one cluster is present.ACCEPTANCE CRITERIA
OF WELDAccording to API 1104, para. 6.3 (Pipeline & Related
Facilities)No.Kind of imperfectionUnacceptance1Inadequate
Penetration without high-low (IP) (Khng thu)Length of individual
indication of IP > 1" (25,4mm)Aggregate length of indications of
IP > 1" in any continuous 12"(304,8mm) length of weldAggregate
length of indications of IP > 8% of the weld length in any weld
less than 12" in length2Inadequate Penetration due to High-Low
(IPD) (Khng thu do ghp lch)Length of individual indication of IPD
> 2" (50,8mm)Aggregate length of indications of IPD > 3"
(76,2mm) in any continuous 12" length of weld3Incomplete fusion
(IF) (khng ngu)Length of an individual indication of IF >
1"Aggregate length of indications of IF > 1" in any continuous
12" length of weldAggregate length of indications of IF > 8% of
the weld length in any weld < 12" in length4Incomplete fusion
due to cold lap (IFD) (khng ngu do chng mp ngui)Length of
individual indication of IFD > 2"Aggregate length of indications
of IFD > 2" in any 12" of the WeldAggregate length of
indications of IFD > 8% of the weld length in any weld less than
12" in length5Internal Concavity (IC) (lm trong)Accept6Burn-Through
(BT) (chy thng chn mi hn)For pipe with an outside diameter 2.3/8"
(60,3mm)Max. dimension > 1/4" (6,35mm) and density of BT's image
> thinnest adjacent base metalMax. dimension > the thinner of
the nominal wall thicknesses joined and density of BT's image >
thinnest adjacent base metalThe sum of the max. dimensions of
separate BTs whose image density exceeds that of thinnest adjacent
base metal > 1/2" (12.7mm) in any continuous 12" length of weld
or the total weld length, whichever is lessFor pipe with an outside
diameter thinnest adjacent base metalMore than one BT of any size
is present and the density of more than one of the images exceeds
of the thinnest adjacent base metal.7Slag Inclusions (X)ESIs:
Elongated slag inclusions (X di).ISIs: Isolated slag inclusions (X
n).For pipe with an outside diameter 2.3/8" (60,3mm)Length of an
ESI indication > 2"The aggregate length of ESI indications >
2" in any continuous 12" weld lengthThe width of an ESI indication
> 1/16" (1,59mm)The aggregate length of ISI indications >
1/2" in any continuous 12" weld lengthThe width of an ISI
indication > 1/8" (3,17mm)The aggregate length of ESI and ISI
indications > 8% of weld lengthFor pipe with an outside diameter
2 times the thinner of the nominal wall thicknesses joined and the
width excceds 1/2 the thinner of the nominal wall thickness
joinedThe aggregate length of ESI and ISI indications > 8% of
weld length8Individual or scattered porosity (P)Size of an
individual pore > 1/8" (3,17mm)Size of an individual pore >
25% of the thinner of the nominal thicknesses joinedThe
distribution of scattered porosity exceeds the concentration
permitted by Fig. 18 or 19.9Cluster porosity (CP) (Cm r kh)Diameter
of CP > 1/2"Aggregate length of CP > 1/2" in any continuous
12" weld lengthAn individual pore within a cluster > 1/16"
(1,59mm) in size10Hollow-bead porosity (HB) (elongated linear
porosity occurs in the root pass) (Bc kh y tm ng hn)Length of an
individual indication of HB > 1/2"Aggregate length of HB > 2"
in any continuous 12" weld lengthIndividual indications of HB, each
> 1/4" (6,35mm) in length, are separated by < 2"The aggregate
length of all indications of HB > 8% of weld length11Crack (C)
(Nt)The crack, of any size or location in the weld, is not crater
or star crackThe crack is a shallow crater crack or star crack
whose length > 5/32" (3,96mm)12Undercuting including cover pass
(EU) and root pass (IU) (Rnh kha)Aggregate length of indications
> 2" in any continuous 12" weld lengthAggregate length of
indications exceeds 1/6 of the weld length13Accumulation of
discontinuities(AD) including IPD and undercuting (tch t cc bt lin
tc bao gm khng thu do ghp lch v chy nhn)Aggregate length of
indications exceeds 2" in any 12" weld lengthAggregate length of
indications exceeds 8% of the weld lengthACCEPTANCE CRITERIA OF
WELD (RT)According to AWS D1.1/D1.1M-2006, para 6.12 (Structural
Welding Code - Steel)No.Kind of imperfectionUnacceptance6.12.1
Acceptance Criteria for Statically Loaded Nontubular Connection (Kt
cu chu ti tnh):6.12.1.1 Discontinuities: Welds that are subject to
RT in addition to visual inspection shall have no cracks and shall
be unacceptable if the RT show any discontinuities excceding the
following limitations (E = weld size)1Elongated discontinuities
(khuyt tt di): Exceeding the maximum size of Fig.
6.12Discontinuities closer than the minimum clearance allowance of
Fig 6.13Rounded discontinuities (khuyt tt dng trn) greater than a
minimum of size of E/3, not to exceed 1/4 in. (6mm). However, when
the thickness is greater than 2in. (50mm), the maximum rounded
indication may be 3.8in. (10mm). The minimum clearance of this type
of discontinuity greater than or equal to 3/32in (2.5mm) to an
acceptable elongated or rouded discontinuity or to an edge or end
of an intersecting weld shall be three times the greatest
diamension of the larger of the discontinuities being
considered.4Isolated discontinuities such as a cluster of rounded
indications, having a sum of their greatest dimensions excceding
the maximum size single discontinuity allowed in fig. 6.1. The
minimum clearance to another cluster or an elongated or rounded
discontinuity or to an edge or end of an intersecting weld shall be
three times the greatest dimension of the larger of the
discontinuities being considered.5The sum of individual
discontinuities each having a greater dimension of less than
3/32in. (2.5mm) shall not exceed 2E/3 or 3.8in. (10mm), whichever
is less, in any linear 1in. (25mm) of weld. This requirement is
independent of (1), (2), and (3) above.6In - line discontinuities,
where the sum of the greatest dimensions exceeds E in any length of
6E. When the length of the weld being examined is less than 6E, the
allowable sum of the greatest dimensions shall be proportionally
less.6.12.1.2 Illustration of requirements: Fig. 6.2 and Fig. 6.3
illustrate the application of the requirements given in
6.12.1.1.6.12.2 Acceptance Criteria for Cyclically Loaded
Nontubular Connection (kt cu chu ti dc trc):Welds that are subject
to RT in addition to visual inspection shall have no cracks and
shall be unacceptable if the RT show any of the types of
discontinuities described in 6.12.2.1, 6.12.2.2, 6.12.2.3, or
6.12.2.4.16.12.2.1 Tesile stress welds: For welds subject to tesile
stress under any condition of loading, the greatest dimension of
any porosity or fusion - type discontinuity that is 1/16in. (2mm)
or larger in greatest dimension shall not exceed the size, B,
indicated in Fig. 6.4, for the weld size involved.- The distance
from any porosity or fusion - type discontinuity described above to
another such discontinuity, to an edge or to the toe or root of any
intersecting flange - to web weld shall be not less than the
minimum clearance allowed, C, indicated in Fig. 6.4 for the size of
discontinuity under examination.26.12.2.2 Compressive stress welds:
For welds subject to compressive stress only and specifically
indicated as such on the design drwings, the greatest dimension of
porosity or a fusion - type discontinuity that is 1/8in. (3mm) or
larger in greatest dimension shall not exceed the size, B, nor
shall be space beween adjacent discontinuities be less than the
minimum clearance allowed, C, indicated by Fig. 6.5, for the size
of discontinuity under examination.36.12.2.3 Discontinuities Less
Than 1/16in.[2mm]: Independent of the requirements of 6.12.2.1 and
6.12.2.2, discontinuities having a greatest dimension of less than
1/16in. (2mm) shall be unacceptable if the sum of their greatest
dimensions exceeds 3/8in. (10mm) in any linear inch of
weld.46.12.2.4 Limitations: The limitations given by Fig. 6.4 and
6.5 for 1 - 1.2 in. (38mm) weld size shall apply to all weld sizes
greater than 1 - 1/2 in. thickness.56.12.2.5 Annex C Illustration:
Annex C illustrates the application of the requirements given in
6.12.2.16.12.3 Acceptance Criteria for Tubular Connections (lin kt
ng):6.12.3.1 Discontinuities: Welds that are subject to RT in
addition to visual inspection shall have no cracks and shall be
unacceptable if the RT show any discontinuities excceding the
following limitations (E = weld size)1Elongated discontinuities
(khuyt tt di) exceeding the maximum size of Fig.
6.62Discontinuities closer than the minimum clearance allowance of
Fig 6.63At the intersection of a weld with another weld or a free
edge (i.e., an edge beyond which no material extension exists),
acceptable discontinuities shall:a) Conform to the limitations of
Fig. 6.6, for each invidual weld.b) Conform to the intersecting
weld limitations of Fig. 6.6, case I or II, as applicable4Isolated
discontinuities such as a cluster of rounded indications, having a
sum of their greatest dimensions excceding the maximum size single
discontinuity permitted in fig. 6.6. The minimum clearance to
another cluster or an elongated or rounded discontinuity or to an
edge or end of an intersecting weld shall be three times the
greatest dimension of the larger of the discontinuities being
considered.5The sum of individual discontinuities each having a
greater dimension of less than 3/32in. (2mm) shall not exceed 2E/3
or 3.8in. (10mm), whichever is less, in any linear 1in. (25mm) of
weld. This requirement is independent of (1), (2), and (3)
above.6In - line discontinuities, where the sum of the greatest
dimensions exceeds E in any length of 6E. When the length of the
weld being examined is less than 6E, the permissible sum of the
greatest dimensions shall be proportionally less.6.12.3.2
Illustration of requirements: Fig. 6.2 and Fig. 6.3 illustrate the
application of the requirements given in 6.12.3.1.
UTACCEPTANCE CRITERIA OF WELD (UT)According to ASME Sec. VIII,
Div. 1, Appendix 12 (Pressure Vessels)No.Kind of
imperfectionUnacceptanceImperfection which produce a response
greater than 20% of the reference level shall be investigated to
the extent that the operator can determine the shape, identity, and
location of all such imperfections and evaluate them in terms of
the acceptance standard below:1Crack (nt)x2Lack of fusion (khng
ngu)x3Incomplete penetration (khng thu)x4Other imperfection (khuyt
tt khc)Length of the imperfection > 1/4" (6mm) for t2.1/4"
(57mm)t - the thickness of weld excluding any allowable
reinforcement. For a butt weld joining two members having different
thickness at the weld, t is the thinner of these two thickness. If
a full penetration weld includes a fillet weld the thickness of the
throat of the fillrt shall be included in t.ACCEPTANCE CRITERIA OF
WELD (UT)According to ASME B31.3, 344.6 (Processing Piping)No.Kind
of imperfectionUnacceptance1A linear type discontinuity is
unacceptable if the amplitude of the indication exceeds the
reference levelLength of the imperfection > 1/4" (6mm) for
t2.1/4" (57mm)Note: Examination of castings is covered in para.
302.3.3. UT of welds shall be performed in accordance with BPV
Code, Sec. V, Article 5.ACCEPTANCE CRITERIA OF WELD (UT)According
to API 1104, para. 6.6 (Pipeline & Related Facilities)No.Kind
of imperfectionUnacceptanceAll indications that produce a response
greater than 20% of the reference level shall, to the degree
possible, be investigated to determine the location, shape, extent,
and type of reflectors and shall be evaluated according to the
following criteria:1Linear indications interpreted to be shallow
crater cracks or star cracks, located at the weld surfaceLength of
indication > 5/12" (3,96mm)2Other crackx3Linear indications
(other than cracks) interpreted to be open to the surfaceTotal
length > 1" in a continuous 12" weld length or 8% of weld
length4Linear indications interpreted to be buried within the
weldTotal length > 2" in a continuous 12" weld length or 8% of
weld lengthNote: Laminations, longseam discontinuities, and other
discontinuities in the pipe or fitting detected by UT shall be
reported to the company. They disposition by repair or removal
shall be as directed by the company.ACCEPTANCE CRITERIA OF
WELDAccording to API 650, API 620No.Kind of
imperfectionUnacceptanceAcceptance standards shall be agreed upon
by the purchaser and the manufacturerACCEPTANCE CRITERIA OF WELD
(UT)According to AWS D1.1/D1.1M-2006, para 6.13 (Structural Welding
Code - Steel)No.Kind of imperfectionUnacceptance6.13.1 Acceptance
Criteria for Statically Loaded Nontubular Connections (kt cu chu ti
trng tnh):The acceptance criteria for welds subject to UT in
addition to visual inspection shall meet the requirements of Table
6.2. For CJP web to flange welds, acceptance of discontinuities
detected by scanning movements other than scanning pattern "E" (see
6.32.2.2) may be base on weld thickness equal to actual web
thickness plus 1in. [25mm]. Discontinuities detected by scanning
pattern "E" shall be evaluated to the criteria of Table 6.2 for the
actual web thickness. When CJP web to flange welds are subject to
calculated tensile stress normal to the weld, they should be so
designated on the design drawing and shall conform to the
requirements of Table 6.2. Ultrasonically tested welds are
evaluated on the basis of a discontinuity reflecting ultrasound in
proportion to its effect on the integrity of the weld. Indications
of discontinuities that remain on the display as the search unit is
moved towards and away from the discontinuity (scanning movement
"b" may be indicative of planar discontinuities with significant
through - throat dimension.Cc mi hn a ra kim tra UT b sung cho kim
tra trc quan s c chp nhn nu chng p ng yu cu trong Bng 6.2. i vi mi
hn lin kt gia bng dm v cnh dm, cc khuyt tt phi c qut theo kiu "E"
(xem mc 6.32.2.2) c th da trn chiu dy mi hn cng vi 1' (25mm). Cc
khuyt tt qut theo dng "E" s c nh gi theo Bng 6.2 i vi dy bng dm thc
t. Khi mi hn lin kt gia bng dm v cnh dm c a ra tnh ton ng sut ko,
chng s c thit k trn bn v thit k v thc hin theo yu cu Bng 6.2. Cc mi
hn kim tra UT c nh gi da trn mt mt phn x tng quan vi nh hng ca n n
tnh ton vn ca mi hn. Cc ch bo khuyt tt th hin trn mn hnh do u d di
chuyn ti v lui t khuyt tt (kiu qut "b" c th ch ra cc khuyt tt phng
vi kch thc trng yu)Since the major reflecting surface of the most
critical discontinuities is oriented a minimum of 20 degree (for a
70 degree seach unit) to 45 degree (for a 45 degree seach unit)
from perpendicular to the sound beam, amplitude evaluation (dB
rating) does not allow reliable disposition. When indications
exhibiting these planar characteristics are present at scanning
sensitivity, a more detailed evaluation of the discontinuity by
other means shall be required (e.g., alternate UT techniques, RT,
grinding or gouging for visual inspection, etc.).6.13.2 Acceptance
Criteria for Cyclically Loaded Nontubular Connections:The
acceptance criteria for welds subject to UT in addition to visual
inspection shall meet the following requirements:1) Welds subject
to tensile stress under any condition of loading shall conform to
the requirements of Table 6.3.2) Welds subject to compressive
stress shall conform to the requirements of Table 6.2.6.13.2.1
Indications: Ultrasonically tested welds are evaluated on the basis
of a discontinuty reflecting ultrasound in proportion to its effect
on the integrity of the weld. Indications of discontinuities that
remain on the display as the seach unit is moved towards and away
from the discontinuity (scanning movement "b") may be indicative of
plannar discontinuities with significant through throat dimension.
As the orientation of such discontinuities, relative to the sound
beam, deviates from the perpendicular, dB ratings which do not
allow direct, reliable evaluation of the welded joint integrity may
result. When indications that exhibit these plannar characteristics
are present at scanning sensitivity, a more detailed evaluation of
the discontinuity by other means may be required (e.g., alternate
UT techniques, RT, grinding or gouging for visual inspection,
etc.).6.13.2.2 Scanning: CJP web - to - flange welds shall conform
to the requirements of Table 6.2 and acceptance for discontinuities
detected by scanning movements other than scanning pattern "E" (see
6.32.2.2) may be base on a weld thickness equal to the actual web
thickness plus 1 in. (25mm). Discontinuities detected by scanning
pattern "E" shall be evaluated to the criteria of 6.13.2 for the
actual web thickness. When such web to flange welds are subject to
calculated tensile stress normal to the weld, they shall be so
designated on design drawings and shall conform to the requirements
of Table 6.3.6.13.3 Acceptance Criteria for Tubular
Connections:Acceptance criteria for UT shall be as provided in
contract documents. Class R or Class X or both may be incorporated
by reference. Amplitude based acceptance criteria as given by
6.13.1 may also be used for groove welds in butt joints in tubing
24in. (600mm) in diameter and over, provided all relevant
provisions of section 6, Part F, are followed. However, these
amplitude criteria shall not be applied to tubular T, Y, and K
connections.6.13.3.1 Class R (Applicable When UT is Used as an
Alternate to RT): All indications having one - half (6dB) or less
amplitude than the standard sensitivity level (with due regard for
6.27.6) shall be disregarded. Indications exceeding the disregard
level shall be evaluated as follows:1) Isolated random spherical
reflectors, with 1 in. (25mm) minimum separation up to the standard
sensitivity level shall be accepted. Larger reflectors shall be
evaluated as linear reflectors.2) Aligned spherical reflectors
shall be evaluated as linear reflectors.3) Clustered spherical
reflectors having a density of more than one per square inch (645
square milimeters) with indications above the disregard levels
[projected area normal to the direction of applied stress, averaged
over a 6 in. (150mm) length of weld] shall be rejected.4) Linear or
planar reflector whose lengths (extent) exceed the limints of Fig.
6.7 shall be reject. Additionally, root reflectors shall not exceed
the limits of Class X.6.13.3.2 Class X (Experience - Bases, Fitness
for Purpose Criteria Applicable to T, Y and K Connections in
Redundant Structures with Notch - Tough Weldments): All indications
having half (6dB) or less amplitude than the standard sensitivity
level (with due regard for 6.27.6) shall be disregarded.
Indications exceeding the disregard level shall be evaluated as
follows:1) Spherical reflectors shall be as described in Class R,
except that any indications within the following limits for linear
or planar are acceptable.2) Linear or planar reflector shall be
evaluated by means of beam boundary techniques, and those whose
dimensions exceeded the limits of Fig. 6.8 shall be reject. The
root are shall be defined as that lying within 1/4 in. (6mm) or
tw/4, whichever is greater, of the root of the theoretical weld, as
shown in Fig. 3.8.ACCEPTANCE CRITERIA OF WELD (UT)According to ASME
Sec. I, PW-52 (Power Boilers)No.Kind of
imperfectionUnacceptanceImperfection which produce a response
greater than 20% of the reference level shall be investigated to
the extent that the operator can determine the shape, identity, and
location of all such imperfections and evaluate them in terms of
the acceptance standard below:1Crack (nt)x2Lack of fusion (khng
ngu)x3Incomplete penetration (khng thu)x4Other imperfection (khuyt
tt khc)Length of the imperfection > 1/4" (6mm) for t2.1/4"
(57mm)t - the thickness of weld excluding any allowable
reinforcement. For a butt weld joining two members having different
thickness at the weld, t is the thinner of these two thickness. If
a full penetration weld includes a fillet weld the thickness of the
throat of the fillrt shall be included in t.
PTACCEPTANCE CRITERIA OF WELD (PT)According to ASME Sec. IX,
QW-191.2 (Welder Qualification)No.Kind of
imperfectionUnacceptance1Relevant linear indicationsx2Relevant
rounded indicationsd > 4,8 mm4 or more relevant rounded
indications in a line separated by 1.6 mm or less, edge to
edgeNote:Relevant indication: the dimension of indication greater
than 1,6mmLinear indication: the length of indication greater than
three times the widthRound indication: the length of indication
less than three times the widthACCEPTANCE CRITERIA OF WELD
(PT)According to ASME Sec. I, A-270 (Power Boilers)No.Kind of
imperfectionUnacceptance1Relevant linear indications (Ch th dng ng
thch hp)x2Revelant rounded indications (ch th trn thch hp)greater
than 4.8 mm4 or more relevant rounded indications in a line
separated by 1.6 mm or less, edge to edgeACCEPTANCE CRITERIA OF
WELD (PT)According to ASME Sec. VIII, Appendix 8 (Pressure
Vessels)No.Kind of imperfectionUnacceptance1Relevant linear
indicationsx2Revelant rounded indicationsgreater than 4.8 mm4 or
more relevant rounded indications in a line separated by 1.6 mm or
less, edge to edgeNote:Indications which have any dimension greater
than 1.6 mm shall be considered relevant.ACCEPTANCE CRITERIA OF
WELD (PT)According to API 1104, para. 6.5 (Pipeline & Related
Facilities)No.Kind of imperfectionUnacceptanceAny indication with a
max. dimension of 1/16" (1,59mm) or less shall be classified as
nonrelevant. Any lager indication believed to be nonrelevant shall
be regarded as relevant until reexamined by PT or another NDT
method to determine whether or not an actual discontinuity exists.
The surface may be ground or otherwise conditioned before
re-examination. After an indication is determined to be
nonrelevent, other nonrelevant indications of the same type need
not be reexamined.1Linear indications are evaluated as crater
cracks or star cracksLength of indication > 5/12"
(3,96mm)2Linear indications are evaluated as cracks other than
crater cracks or star cracksx3Linear indications are evaluated as
IF (Incomplete Fusion)Total length > 1" in a continuous 12"
(304.8mm) weld length or 8% of weld length4Rounded indicationTo be
evaluated according to Individual or scattured porosity (P) &
Cluster porosity (CP) in RTIndividual or scattured porosity (P)Size
of an individual pore > 1/8" (3,17mm)Size of an individual pore
> 25% of the thinner of the nominal thicknesses joinedThe
distribution of scattered porosity exceeds the concentration
permitted by Fig. 18 or 19.Cluster porosity (CP)Diameter of CP >
1/2"Aggregate length of CP > 1/2" in any continuous 12" weld
lengthAn individual pore within a cluster > 1/16" (1,59mm) in
sizeACCEPTANCE CRITERIA OF WELD (PT)According to API 650, API
620No.Kind of imperfectionUnacceptanceAcceptance standards shall be
in accordance with section VIII, Appendix 8 of the ASME
CodeACCEPTANCE CRITERIA OF WELD (PT)According to ASME B31.3 Table
341.3.2 (Process Piping)No.Kind of imperfectionUnacceptanceNormal
Fluild serviceSevere Cyclic Conditions1Crack (nt)xxACCEPTANCE
CRITERIA OF WELD (PT)According to AWS D1.1/D1.1M-2006, para 6.10
(Structural Welding Code - Steel)No.Kind of
imperfectionUnacceptanceWelds that are subject to magnetic -
particle and liquid penetrant testing, in addition to visual
inspection shall be evaluated on the basis of the requirements for
visual inspection. The testing shall be performed in conformance
with 6.14.4 or 6.14.5, whichever is applicable.
MTACCEPTANCE CRITERIA OF WELD (MT)According to ASME Sec. VIII,
Appendix 6 (Pressure Vessels)No.Kind of
imperfectionUnacceptance1Relevant linear indications (Ch th dng ng
thch hp)x2Revelant rounded indications (ch th trn thch hp)greater
than 4.8 mm4 or more relevant rounded indications in a line
separated by 1.6 mm or less, edge to edgeNote:Indications which
have any dimension greater than 1.6 mm shall be considered relevant
(Cc ch th c kch thc ln hn 1.6mm c gi l thch hp).ACCEPTANCE CRITERIA
OF WELD (MT)According to ASME Sec. I, A-260 (Power Boilers)No.Kind
of imperfectionUnacceptance1Relevant linear indications (Ch th dng
ng thch hp)x2Revelant rounded indications (ch th trn thch
hp)greater than 4.8 mm4 or more relevant rounded indications in a
line separated by 1.6 mm or less, edge to edgeACCEPTANCE CRITERIA
OF WELD (MT)According to API 1104, para. 6.5 (Pipeline &
Related Facilities)No.Kind of imperfectionUnacceptanceAny
indication with a max. dimension of 1/16" (1,59mm) or less shall be
classified as nonrelevant. Any lager indication believed to be
nonrelevant shall be regarded as relevant until reexamined by MT or
another NDT method to determine whether or not an actual
discontinuity exists. The surface may be ground or otherwise
conditioned before re-examination. After an indication is
determined to be nonrelevent, other nonrelevant indications of the
same type need not be reexamined.1Linear indications are evaluated
as crater cracks or star cracksLength of indication > 5/12"
(3,96mm)2Linear indications are evaluated as cracks other than
crater cracks or star cracksx3Linear indications are evaluated as
IF (Incomplete Fusion)Total length > 1" in a continuous 12" weld
length or 8% of weld length4To be evaluated according to Individual
or scattured porosity (P) & Cluster porosity (CP) in
RTIndividual or scattured porosity (P)Size of an individual pore
> 1/8" (3,17mm)Size of an individual pore > 25% of the
thinner of the nominal thicknesses joinedThe distribution of
scattered porosity exceeds the concentration permitted by Fig. 18
or 19.Cluster porosity (CP) (Cm r kh)Diameter of CP >
1/2"Aggregate length of CP > 1/2" in any continuous 12" weld
lengthAn individual pore within a cluster > 1/16" (1,59mm) in
sizeACCEPTANCE CRITERIA OF WELD (MT)According to ASME B31.3 Table
341.3.2 (Process Piping)No.Kind of imperfectionUnacceptanceNormal
Fluild serviceSevere Cyclic Conditions1Crack (nt)xxACCEPTANCE
CRITERIA OF WELD (MT)According to API 650, API 620No.Kind of
imperfectionUnacceptanceAcceptance standards shall be in accordance
with section VIII, Appendix 6 of the ASME CodeACCEPTANCE CRITERIA
OF WELD (MT)According to AWS D1.1/D1.1M-2006, para 6.10 (Structural
Welding Code - Steel)No.Kind of imperfectionUnacceptanceWelds that
are subject to magnetic - particle and liquid penetrant testing, in
addition to visual inspection shall be evaluated on the basis of
the requirements for visual inspection. The testing shall be
performed in conformance with 6.14.4 or 6.14.5, whichever is
applicable.
Visual InspectionACCEPTANCE CRITERIA OF WELD (VT)According to
ASME B31.3, para 344.2 (Processing piping)No.Kind of
imperfectionUnacceptanceVisual examination shall be performed in
accordance with the BPV Code, Section V, Article 9. Record of
invidual visual examinations are not required, except for those of
in - process examination as specified in para. 344.7 (Kim tra trc
quan c thc hin ph hp vi BPV Code, Sec. V, Article 9. Khng yu cu lp
bo co kim tra trc quan ring bit, ngoi tr cc kim tra c ch ra trong
344.7)ACCEPTANCE CRITERIA OF WELD (VT)According to API 1104, para
3.4 & 6.7 (Pipeline & Related Facilities)No.Kind of
imperfectionUnacceptanceFor a qualification test weld to meet the
requrements for visual examination, the weld shall be free cracks,
inadequate penetration, burn-through and other defects and must
present a neat workmanlike appearance.1Undercuting adjacent to the
cover or root bead (chy chn hoc git li)The deepth > 1/32"
(0,79mm) or 12,5% of the pipe wall thickness, whichever is
smaller.The deepth > 1/64" (0,4mm) or > 6%-12,5% of pipe wall
thickness, whichever is smaller, and length of undercuting 2"
(50,8mm) in a continuous 12" (304,8mm) weld length or 1/6 the weld
length, whichever is smaller.ACCEPTANCE CRITERIA OF WELD
(VT)According to AWS D1.1/D1.1M-2006, para 6.9 & Table 6.1
(Structural Welding Code - Steel)6.9 All welds shall be visually
inspected and shall be acceptable if criteria of Table 6.1 are
satisfied.No.Discontinuity Category and Inspection
CriteriaStatically loaded nontubular connectionsCyclically loaded
nontubular connectionsTubular connections (All loads)1Crack
prohibition (nghim cm cc vt nt):Any crack shall be unacceptable,
regardless of size or location (mi vt nt u khng chp nhn bt k kch
thc v v tr)XXX2Weld/Base - Metal Fusion (ngu mi hn v kim loi c
bn):Thorough fusion shall exist beween adjecent layers of weld
metal and beween weld metal and base metal (Gia cc lp hn v gia kim
loi hn v kim loi c bn phi nhu hon ton)XXX3Crater Cross Section (mt
ct ngang ming hn):All craters shall be filled to provide the
specified weld size, except for the ends of intermittent fillet
welds outside of their effective length (tt c cc ming hn phi c in y
nh kch thc mi hn c thit k, ngoi tr i vi cc im cui cc mi hn gc khng
lin tc pha ngoi chiu di hiu dng ca chng)XXX4Weld profiles (Profile
mi hn):Weld profiles shall be in conformance with 5.24 (Profile mi
hn ph hp mc 5.24) 5.24. All welds meet the visual acceptance
criteria of Table 6.1 and shall be free from cracks, overlaps, and
the unacceptable profile discontinuities exhibited in Fig. 5.4
except as otherwise allowed in 5.24XXX5Time of Inspection (thi gian
kim tra):Visual inspection of welds in all steels may begin
immediately after the completed welds have cooled to ambient
temperature. Acceptance criteria for ASTM A 514, A 517 and A 709
Grade 100 and 100W steels shall be based on visual inspection
performed not less than 48 hours after completion of the weld. (Vic
kim tra trc quan mi hn ca tt c cc loi thp c th bt u ngay sau khi mi
hn hon thnh c lm lnh n nhit xung quanh. i vi thp ASTM A 514, 7 v
A709 grade 100 v 100W vic kim tra trc quan s thc hin sau khi hn
xong t nht 48 ting)XXX6Undersized welss:The size of a filled weld
in any continuous weld may be less than the specified nominal size
(L) without correction by the following amounts (U): L, U,specified
nominal weld size, in. [mm] allowable decrease from L, in. [mm]
3/16 [5] 1/16 [2] 1/4 [6] 3/32 [2.5] 5/16 [8] 1/8 [3]In all cases,
the undersize portion of the weld shall not exceed 10% of the weld
length. On web-to-flange welds on girders, underrun shall be
prohibited at the ends for a length equal to twice the width of the
flange.XXX7Undercut (chy chn):(A) For material less than 1 in.
(25.4mm) thick, undercut shall not exceed 1/32 in. (1mm), with the
following exception: undercut shall not exceed 1/16 in. (2mm) for
any accumulated length of 2 in. (50mm) in any 12 in. (300mm). For
material equal to or greater than 1 in. thick, undercut shall not
exceed 1/16 in. [2mm] for any length of weld.X(B) In primary
members, undercut shall be no more than 0.01 in. (0.25mm) deep when
the weld is transverse to tensile stress under any design loading
condition. Undercut shall be no more than 1/32 in. (1mm) deep for
all other cases.XX8Porosity (r kh):(A) CJP groove welds in butt
joints transverse to the direction of computed tensile stress shall
have no visible piping porosity. For all other groove welds and for
fillet welds, the sum of the visible piping porosity 1/32in. (1mm)
or greater in diameter shall not exceed 3/8 in. (10mm) in any
linear inch of weld and shall not exceed 3/4in. (20mm) in any 12
in. (300mm) length of weld.X(B) The frequency of piping porosity in
fillet welds shall not exceed one in each 4 in. (100mm) of weld
length and the maximum diameter shall not exceed 3/32 in. (2.5mm).
Exception: for fillet welds connecting stiffeners to web, the sum
of the diameters of piping porosity shall not exceed 3/8in. (10mm)
in any linear inch of weld and shall not exceed 3/4 in. (20mm) in
any 12 in. (300mm) length of weld.XX(C) CJP groove welds in but
joints transverse to the direction of computed tensile stress shall
have no piping porosity. For all other groove welds, the frequency
of piping porosity shall not exceed one in each 4 in. (100mm) of
length and the maximum diameter shall not exceed 3/32 in.
(2.5mm).XXAn "X" indicates applicability for the connection type; a
shaded area indicates non - applicability.
PWHTPOSTWELD HEAT TREATMENT REQUIREMENTS FOR CARBON AND LOW
ALLOY SREELSAccording to ASME Sec. VIII, Div 1 (TABLE UCS-56)
(Pressure Vessels)Base Metal P-No. or S-No. [Note (1)]Normal
Holding Temp, oF (oC), minimumBase Metal groupNorminal Wall
ThicknessSpecified Min. Tensile strength, Base MetalMetal
Temperature RangeHolding timeBrinell hardness [Note (4)],
max.Norminal wall [Note (4)] max.Min. time,
(hr)mminchMpaksi0C0Fmin/mmhr/in11carbon steel19POSTWELD HEAT
TREATMENT REQUIREMENTS FOR CARBON AND LOW ALLOY SREELSAccording to
ASME Sec. VIII, Div 1 (TABLE UCS-56) (Pressure
Vessels)MaterialNormal Holding Temp, oF (oC), minimumUp to 2 in.
(51mm)
Leak Testing
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