关于船舶无损检测与IACSRec20标准说明(DOC 10页).doc

船体结构焊缝进行无损检测（Non-destructive testing of ship hull steel welds）中国船舶工业无损检测标准（CB/T）与IACS Rec. 20标准的比较说明Brief introduction for comparing Chinese shipbuilding NDT standards (CB/T) with IACS REC 20几乎所有的中国船厂采用以下无损检测标准对船体结构焊缝进行无损检测：CB/T3177-94（船舶钢焊缝射线照相和超声波检查规则）、CB/T3558-94（船舶钢焊缝射线照相工艺和质量分级）、CB/T3559-94（船舶钢焊缝手工超声波探伤工艺和质量分级）、CB/T3958-2004（船舶钢焊缝磁粉、渗透检测工艺和质量分级）Almost all Chinese shipyards adopt following recognized NDT standards for non-destructive testing of ship hull steel welds： CB/T3177-94（Ship steel weld radiographic testing and UT testing standard， CB/T3558-94（Ship steel weld radiographic testing technology and quality classification）， CB/T3559-94（Ship steel weld UT testing technology and quality classification）and CB/T3958-2004 （Ship steel weld magnetic particle & penetration testing technology and quality classification）在IACS URZ23 和 IACS Rec. 47中提及使用IACS Rec. 20对船体结构焊缝进行无损检测，为了便于验船师检查无损检测结果，现将上述标准与IACS Rec. 20标准的比较结果具体如下：In IACS URZ23 and IACS Rec. 47, IACS.20 is referred to be applied for non-destructive testing of ship hull steel welds. In order to convenience for surveyor checking NDT results, full comparison between above mentioned national NDT standards with IACS.20 are done, see the contrast tables and conclusions as follows: 一、射线照相检测radiographic testing:表1 / Table 1：透照厚度范围及其像质计要求Nominal thickness range and wire number visible on the filmCB/T3558-94标准standardIACS Rec. 20标准透照厚度Nominal thickness range金属丝指数（直径）Wire number visible on the film (nominal diameter)厚度范围Nominal thickness range金属丝指数（直径）Wire number visible on the film (nominal diameter)普通级Normal class/16（0.100）5t7W14（0.16）615（0.125）6814（0.16）5t7W14（0.16）7t10W13（0.20）81213（0.20）7t10W13（0.20）10t15W12（0.25）121612（0.25）10t15W12（0.25）15t25W11（0.32）162011（0.32）15t25W11（0.32）202510（0.40）15t25W11（0.32）25329（0.50）25t32W10（0.40）325032t408（0.63）32t40W9（0.50）40t508（0.63）40t55W8（0.63）508050t557（0.80）40t55W8（0.63）55t807（0.80）55t85W7（0.80）8012080t856（1.00）55t85W7（0.80）85t1206（1.00）85t150W6（1.00）1201505（1.25）85t150W6（1.00）1502004（1.60）/表1/Table 1：1. 比较CB普通级绿色数据与IACS REC 20的相应数据要求，在相同的透照范围内，透照灵敏度（发现金属丝指数）即像质计要求，CB/T3558-94标准的普通级严于IACS Rec. 20的要求；Regarding wire number visible on the film (nominal diameter) i.e. IQI, comparing green figures between CB/T3558-94 (normal class) and IACS REC 20, within the same nominal thickness range, found that IQI (normal class stipulated on CB/T3558-94) is much more stringent than that of REC 20.2. 比较CB普通级红色IQI数据与IACS REC 20的IQI数据要求，在相同的透照范围内，透照灵敏度（发现金属丝指数）即像质计要求CB/T3558-94标准的普通级小于IACS Rec. 20的要求；Regarding wire number visible on the film (nominal diameter) i.e. IQI, comparing red figures between CB/T3558-94 (normal class) and IACS REC 20, within the same nominal thickness range, found that IQI (normal class stipulated on CB/T3558-94) is less stringent than that of REC 20.3. 所以船厂或无损检测公司在射线照相透照灵敏度（发现金属丝指数）上，可以使用CB/T3558-94标准的普通级要求，并注意在此情况下与IACS Rec. 20要求相一致，即在X射线片子上看到相应要求的金属丝指数。Hence, shipyard or NDT company may adopts CB/T3558-94 standards wire number visible on the film (nominal diameter), but shipyard has to pay attention to be in line with required IQI stipulated on IACS REC 20, i.e. required wire number visible on the film (nominal diameter), then it can meet IACS REC 20.表2 / Table 2：底片密度（黑度）范围The optical density of radiographs range on filmCB/T3558-94标准IACS Rec. 20标准射线种类Kind of ray底片黑度Film density底片黑度Film densityX射线X-ray普通级Normal class1.204.00参见ISO17636要求Refer to ISO17636射线-ray1.84.00表2 / Table 2：比较CB/T3558-94标准中，射线照相底片密度能够满足IACS Rec. 20标准；如船厂或无损检测公司在实际使用X射线照相时，操作人员应通过使用适当设备或增加曝光量等，使底片密度达到IACS REC 20的要求，这样就可以满足IACS Rec. 20标准对底片密度的要求。Comparing CB/T3558-94, -ray can meet requirement of film density stipulated on IACS REC 20; in case shipyard or NDT company, are using of X-ray in normal practices, NDT operator should choose suitable X-ray equipment or increase exposal etc. to meet IACS Rec. 20 requirement on film density.*注：根据IACS REC 20所述，黑度由船厂或无损检测公司根据ISO17636的表5进行选择：*Note：Acc. to requirement stipulated on IACS REC 20 (6.5.8), the optical density of the radiographs should be selected by the shipyard in accordance with table 5 of ISO17636:ISO17636表5 / ISO17636 table 5Optical density of the radiographs等级Class黑度a / DensityaA（普通级）/（Normal class）2.0bB（较高级）/（Upper class2.3ca：测量允许误差为0.1 / Measuring tolerance of 0.1 is permittedb：经合同各方商定，可将为1.5 / May be reduced to 1.5 if specified, e.g. in an application standard. c：经合同各方商定，可将为2.0 / May be reduced to 2.0 if specified, e.g. in an application standard.表3 / Table 3：IACS Rec. 20标准 射线照相质量分级Acceptance criteria for radiographic testing - IACS REC 20缺陷种类Discontinuity接受标准Acceptance criteria for radiographic testing)裂纹Crack不接受Not accepted未熔合Lack of fusion单个缺陷最大接受长度t/2或25mm，两者取小者；间断缺陷总计最大接受长度t或50mm，两者取小Continuous) maximum length t/2 or 25 mm whichever is the less intermittent cumulative) length maximum t or 50 mm未焊透Incomplete root penetration位于十字接头的单面对接接头焊缝不接受Not accepted in butt joint welded from one side单个缺陷最大接受长度t/2或25mm，两者取小者；间断缺陷总计最大接受长度t或50mm，两者取小Continuous) maximum length t/2 or 25 mm whichever is the less intermittent cumulative) length maximum t or 50 mm夹渣Slag inclusion单个缺陷最大接受长度t或50mm，两者取小者；间断缺陷总计最大接受长度2t或100mm，两者取小Continuous) maximum length t or 50 mm whichever is the less intermittent cumulative) length maximum 2t or 100 mm注 Note:): “t”取焊接板材的最小厚度。 “t” is the plate thickness of the thinnest plate.): 两个相邻的单个间断缺陷长度L1和L2之间的直线距离L凡是小于其中最短的一个间断缺陷长度，均应视作一个连续的长形缺陷L1+L+L2。Two adjacent individual discontinuities of length L1 and L2 situated on a line and where the distance L between them is shorter than the shortest discontinuity should be regards as a continuous discontinuity of length L1+L+L2.): 单个连续的间断缺陷长度的总和。Sum of the length of individual continuous discontinuities.): 如果从焊缝的横向上测量，平行夹渣之间的距离小于最大夹渣宽度的3倍，这些夹渣应被视作为同一条间断面。Parallel inclusions not separated by more than 3 times the width of the largest inclusion should be regarded as one continuous discontinuity.表4 / Table 4：CB/T3558-94标准 射线照相质量分级Acceptance criteria for radiographic testing - CB/T3558-94缺陷种类Kinds of flaws评级Classfying接受标准Acceptance criteria裂纹Crack不评级或大于Non-class or greater than class V不接受Not accepted未熔合Lack of fusion不评级或大于Non-class or greater than class V不接受Not accepted未焊透Incomplete root penetration不评级或大于Non-class or greater than class V不接受Not accepted圆形缺陷（长宽比小于等于3，包括气孔、点状夹杂）Rotundity flaws (ratio of length VS width less or equal to 3, incl. pore, point type slag) 评级Classification评定区尺寸Size for assessment zone 不计点数评级Classification without counting number of point10*1010*2010*30母材厚度Plate thickness1010151525255050100100圆形缺陷个数Number of rotundity flaws36912151815510152025302071421283542259182736455430点数多于（长径尺寸大于t/2）“Number of point” more than IV (length dimension greater than t/2)长形缺陷（长宽比大于3，夹杂或长形气孔）Length- flaws (ratio of length VS width is greater than 3, slag or length of pore)单个长形缺陷限值Single limited length- flaws长形缺陷在任意12t焊缝长度内的限值Threshold level for length- flaws existing on length as 12t at random评级Classification母材厚度Plate thickness12124848单个缺陷尺寸Size of single flaws41/3t16不大于tNot greater than t61/2t24不大于1.5tNot greater than 1.5t82/3t32不大于2tNot greater than 2t106/5t40不大于3tNot greater than 3t大于者The one greater than IV表3和表4比较 Results after comparing Table 3 and Table 4：1. 裂纹、未焊透、未熔合等危害性缺陷在CB/T3558-94标准中是不接受的，在IACS Rec. 20标准中可以接受一定长度的未熔合和未焊透缺陷；Crack, incomplete root penetration and lack of fusion etc. is not accepted as per CB/T3558-94, but certain length of incomplete root penetration and lack of fusion (specified on IACS REC 20) could be accepted as per IACS REC 20.2. 在两标准中夹渣的分级和评价，例如选取厚度为20mm的焊缝作缺陷评定，在IACS Rec. 20标准中可以接受的单个夹渣长度为20mm，在CB/T3558-94标准中II级和III级合格的夹渣的许可长度为10mm和13mm；间断的累计缺陷允许长度分别为: REC 20 为40mm、CB/T3558-94为小于30mm、小于40mm；Regarding classifying slag flaws related to CB/T 3558-94 & IACS REC 20, for example, selected plate thickness as 20 mm for classifying, single length of slag flaws as 20 mm could be accepted; but acc. to CB/T 3558-94, accepted length of slag flaws for class II & III are 10mm, 13 mm; intermittent cumulative length are 40mm for REC 20, less than 30mm and less than 40mm for CB/T3558-943. 一般来讲，船厂或无损检测公司在实际评片中使用的合格等级至少为II级（III级合格为船舯部0.6L之外等），所以CB/T3558-94标准的缺陷评价分级要严于IACS) Rec. 20标准的要求。General speaking, during normal classification practice, shipyard or NDT company shall adopt lowest class as class II (Class III shall be accepted when out of 0.6 L area), so classifying requirement of CB/T 3558-94 is much more stringent than that of REC 20.二、超声波检测Ultrasonic testing:表5 / Table 5：DAC曲线 / DAC curveCB/T3559-94 母材厚度Plate thicknessARL(判废线）DRL（测长区分线）MRL（测长线）5033-10dB3-16dB503+2dB3-6dB3-12dBIACS Rec. 20测长线MRL评定线Evaluation Line大于100%的DAC曲线的波高（3孔径）Greater than 100% of DAC curve (3)回波高度在DAC缺陷50100%之间（3孔径）Greater than 50% but less than 100% of DAC curve (3)低于33%的DAC曲线的波高（3-10dB）Less than 33% of DAC curve (3-10dB)表6 / Table 6：超声波探伤焊缝质量分级Acceptance criteria for Ultrasonic testingIACS Rec. 20CB/T3559-94回波高度ECHO Height接受标准Acceptance criteria评级Classification单个缺陷指示长度Indicated length for single flaw在6t或150mm 焊缝长度内In length of 6t or 150 mm welding seamt/3，最小8，最大24t/3, Min. 8, Max. 242t大于100%的DAC曲线的回波高度Greater than 100% of DAC curve单个缺陷最大接受长度t/2或25mm，两者取小者；Max. length t/2 or 25 mm whichever is the lesst/2，最小12，最大36t/2, Min. 12, Max. 362.5t回波高度在DAC缺陷50100%之间Greater than 50% but less than 100% of DAC curve单个缺陷最大接受长度t或50mm，两者取小者；Max. length t or 50 mm whichever is the less3/4t，最小16，最大483/4t, Min. 16, Max. 483t评估认为是裂纹的，不管回波高度都是不接受Indications evaluated to be cracks are unacceptable regardless of ECHO heightt，最小20，最大60t, Min. 20, Max. 604t在接头的单面焊缝评估认为是未焊透的，不管回波高度都是不接受Indications evaluated to be lack of root penetration in joints welded from one side are unacceptable regardless of ECHO height大于者（裂纹、未焊透、未熔合）The one greater IV (Crack, lack of root penetration, lack of fusion)表5、表6 / Table 5, Table 6：1. 在CB/T3559-94标准中，根据缺陷的波高和指示长度及分布状态，把焊缝质量分为级；高于ARL (判废线）的缺陷回波均评定为级；低于或等于MRL（测长线）的缺陷回波可评定为级；超过MRL（测长线）到ARL(判废线）之间的缺陷回波，据所测定的指示长度按分级表评级；As per CB/T3559-94, classifying welding seam quality as class IV, the one higher than ARL shall be class V; the one less than or equal to MRL could be class I; the ones exceed MRL but below ARL shall be classified as per actual measured length.2. 在IACS Rec. 20标准中，规定了测长线和评定线的回波高度，测长线和评定线相当于ARL (判废线）和DRL（测长区分线）；As per IACS REC 20, specified ECHO height of MRL and evaluation Line classifying welding seam quality as class IV, the one higher than ARL shall be class V; the one less than or equal to MRL could be class I; the one exceed MRL but below ARL shall be classified as per actual measured length3. 对于缺陷的评定Acceptance criteria：1） 在IACS Rec. 20标准中，大于100%的DAC曲线的回波高度，单个缺陷最大接受长度t/2或25mm，两者取小者；在CB/T3559-94标准中，评定为判废不接受；As per IACS REC 20, greater than 100% of DAC curve, acceptance criteria is that Max. length t/2 or 25 mm whichever is the less; but it could not be accepted as per CB/T 3559-94.2） 在IACS Rec. 20标准中，回波高度在DAC缺陷50100%之间，单个缺陷最大接受长度t或50mm，两者取小者；在CB/T3559-94标准中，据所测定长度评级；例如选取厚度为20mm的焊缝作缺陷评定，可以接受的单个夹渣长度为分别为20mm、10mm（II级合格）、15mm（III级合格）；As per IACS REC 20, greater than 50% but less than 100% of DAC curve, acceptance criteria is that Max. length t or 50 mm whichever is the less; but as per CB/T 3559-94, acceptance criteria is based on “indicated length for single flaw”, such as, selected thickness as 20 mm, accepted length for single slag is 20 mm, 10 mm (class II), 15 mm (class III).3） 在IACS Rec. 20标准中，低于33%的DAC曲线的波高（3-10dB）评定为合格，在CB/T3559-94标准中，低于或等于MRL（测长线）的缺陷回波可评定为级；As per IACS REC 20, less than 33% of DAC curve (3-10dB) could be accepted; as per CB/T 3559-94, ECHO height lower or equal to MRL could be accepted as Class I.4） 评估认为是裂纹、未焊透、未熔合的，两者都不接受；Both of IACS REC 20 and CB/T 3559-94 not accept that Indications evaluated to be cracks, lack of root penetration and lack of fusion regardless of ECHO height.4. 船厂或无损检测公司一般至少采用CB/T3559-94标准的II级为合格。Shipyard or NDT company at least to adopt “Class II” as accepted class ac. to CB/T 3559-94.5. 所以超声波标准即CB/T3559-94高于IACS Rec. 20标准的要求。So UT requirement of CB/T 3558-94 is much more stringent than that of REC 20.三、磁粉/渗透检测Magnetic particle & liquid penetration testing:表7 / Table 7：磁粉、渗透探伤焊缝质量分级Acceptance criteria for Magnetic particle & liquid penetration testingIACS Rec. 20CB/T3958-2004表面缺陷Surface discontinuity接受标准Acceptance criteria评定区尺寸Size for assessment zone评级Classification单个缺陷指示长度Indicated length for single flaw35*1000.5裂纹Crack不接受Not accepted0.52.0未熔合Lack of fusion不接受Not accepted24在对接接头的单面焊缝未焊透Incomplete root penetration in butt joints welded from one side不接受Not accepted48表面气孔Surface pore在对接接头上的单个气孔直径0.25t（角焊缝的单个气孔直径0.25a)，但最大直径3mm；相邻气孔最小间距为2.5倍的直径Single pore diameter d0.25t) for butt welds (d0.25a) for fillet welds) with Max. diameter 3 mm; 2.5d as Min. distance to adjacent pore.8对接接头的焊缝咬边Undercut in butt welds无论多长，但深度0.5mm；深度0.8mm，最大缺陷长度不超过90mmDepth 0.5 mm whatever is the lengthDepth 0.8 mm with a Max. continuous) length of 90 mm不允许缺陷Unacceptable flaws裂纹、未熔合、任何长度大于3mm的线状缺陷、任何单个直径大于4mm的圆形缺陷Cracks, lack of fusion, any length over 3 mm for lined flaws and any dia. over 4 mm for rotundity flaws.在角焊缝上的咬边Undercut in fillet welds任何长度，但深度0.8mmDepth 0.8 mm whatever is the lengthNote:): “t”取焊接板材的最小厚度， “a”是焊喉。 “t” is the plate thickness of the thinnest plate and “a” is the throat of fillet weld.): 相邻的焊缝咬边间距凡是小于其中最短的咬边长度，均应视作一个连续的咬边缺陷Adjacent undercuts separated by a distance shorter than the shortest undercut should be regarded as a single continuous undercut.表7 / Table 7：1. 评估认为是裂纹、未焊透、未熔合的，两者都不接受；Both of IACS REC 20 and CB/T 3559-94 not accept that Indications evaluated to be cracks, lack of root penetration and lack of fusion.2. 在CB/T3958-2004标准中，任何长度大于3mm的线状缺陷、任何单个直径大于4mm的圆形缺陷，不接受；As per CB/T 3958-2004, not accept any length over 3 mm for lined flaws and any dia. over 4 mm for rotundity flaws.3. 在IACS Rec. 20标准中，表面气孔可以接受的尺寸为在对接接头上的单个气孔直径0.25t（角焊缝的单个气孔直径0.25a)，但最大直径3mm；相邻气孔最小间距为2.5倍的直径；在CB/T3958-2004标准中，单个缺陷指示长度可接受的长度0.52.0（II级合格）和24（III级合格）；As per IACS REC 20, acceptance criteria for single pore diameter d0.25t) for butt welds (d0.25a) for fillet welds) with Max. diameter 3 mm; 2.5d as Min. distance to adjacent pore; As per CB/T 3958-2004, acceptance criteria for “Indicated length for single flaw” is 0.52.0 (Class II) and 24 (Class III).4. 船厂或无损检测公司一般至少采用CB/T3958-2004标准的II级为合格；Shipyard or NDT company at least to adopt “Class II” as accepted class ac. to CB/T 3958-2004.5. 所以磁粉/渗透检测标准即CB/T3958-2004高于IACS Rec. 20标准的要求。So MT/PT requirement of CB/T3958-2004 is much more stringent than that of REC 20.中国船舶工业无损检测标准（CB/T）与IACS Rec. 20标准的比较结(Conclusion): 1. 射线探伤： 接受标准采取中国船舶工业射线照相(CB/T3558-94) 标准是高于IACS Rec. 20中相关要求的。但在进行射线照相时应注意以下2个事项。 RT the acceptance criteria in CB/T3558-94 is stringent then IACS Re. 20, however following 2 items should be taken into full consideration at the process of performing radiographic test: a) 关于射线照相透照灵敏度（发现金属丝指数）：船厂或无损检测公司可以使用CB/T3558-94标准的普通级要求，但同时需充分考虑并满足IACS Rec. 20规定的要求，即在X射线片子上看到相应要求（较高部分）的金属丝指数， 详见下表。Regarding wire number visible on the film (nominal diameter): shipyard or NDT company may adopts CB/T3558-94 with full consideration of IACS REC 20