关于中国船舶工业无损检测标准与标准的比较说明模板.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）和IACS Rec. 20标准比较说明
Brief introduction for comparing Chinese shipbuilding NDT standards (CB/T) with IACS REC 20

几乎全部中国船厂采取以下无损检测标准对船体结构焊缝进行无损检测：
CB/T3177-94（船舶钢焊缝射线摄影和超声波检验规则）、CB/T3558-94（船舶钢焊缝射线摄影工艺和质量分级）、CB/T3559-94（船舶钢焊缝手工超声波探伤工艺和质量分级）、CB/T3958-（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- （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，为了便于验船师检验无损检测结果，现将上述标准和IACS Rec. 20标准比较结果具体以下：
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、射线摄影检测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 film
CB/T3558-94标准standard
IACS 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)
一般级
Normal class
/
16（0.100）
5
10
55r 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一般级红色IQI数据和IACS REC 20IQI数据要求，在相同透照范围内，透照灵敏度（发觉金属丝指数）即像质计要求CB/T3558-94标准一般级小于IACS Rec. 20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企业在射线摄影透照灵敏度（发觉金属丝指数）上，能够使用CB/T3558-94标准一般级要求，并注意在此情况下和IACS Rec. 20要求相一致，即在X射线片子上看到对应要求金属丝指数。Hence, shipyard or NDT company may adopts CB/T3558-94 standard’s 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 film
CB/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 density
X射线
X-ray
一般级
Normal class
1.20~4.00
参见ISO17636要求
Refer to ISO17636
γ射线
γ-ray
1.8~4.00

表2 / Table 2：
比较CB/T3558-94标准中，γ射线摄影底片密度能够满足IACS Rec. 20标准；如船厂或无损检测企业在实际使用X射线摄影时，操作人员应经过使用合适设备或增加曝光量等，使底片密度达成IACS REC 20要求，这么就能够满足IACS Rec. 20标准对底片密度要求。
Comparing CB/T3558-94, γ-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：依据IACS REC 20所述，黑度由船厂或无损检测企业依据ISO17636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 5
Optical density of the radiographs
等级Class
黑度a / Densitya
A（一般级）/（Normal class）
≥2.0b
B（较高级）/（Upper class
≥2.3c
a：测量许可误差为±0.1 / Measuring tolerance of ±0.1 is permitted
b：经协议各方约定，可将为1.5 / May be reduced to 1.5 if specified, e.g. in an application standard.
c：经协议各方约定，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 射线摄影质量分级
Acceptance criteria for radiographic testing - IACS REC 20
缺点种类
Discontinuity
接收标准
Acceptance criteria for radiographic testing¹)
裂纹
Crack
不接收
Not accepted
未熔合
Lack of fusion
单个缺点最大接收长度t/2或25mm，二者取小者；间断缺点总计最大接收长度t或50mm，二者取小
Continuous²) maximum length t/2 or 25 mm whichever is the less intermittent cumulative³) length maximum t or 50 mm
未焊透
Incomplete root penetration
在十字接头单面对接接头焊缝不接收
Not accepted in butt joint welded from one side
单个缺点最大接收长度t/2或25mm，二者取小者；间断缺点总计最大接收长度t或50mm，二者取小
Continuous²) maximum length t/2 or 25 mm whichever is the less intermittent cumulative³) length maximum t or 50 mm
夹渣
Slag inclusion
单个缺点最大接收长度t或50mm，二者取小者；间断缺点总计最大接收长度2t或100mm，二者取小
Continuous²) maximum length t or 50 mm whichever is the less intermittent cumulative³)’) length maximum 2t or 100 mm
注 Note:
¹): “t”取焊接板材最小厚度。 “t” is the plate thickness of the thinnest plate.
²): 两个相邻单个间断缺点长度L1和L2之间直线距离L通常小于其中最短一个间断缺点长度，均应视作一个连续长形缺点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.
³): 单个连续间断缺点长度总和。Sum of the length of individual continuous discontinuities.
): 假如从焊缝横向上测量，平行夹渣之间距离小于最大夹渣宽度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 射线摄影质量分级
Acceptance criteria for radiographic testing - CB/T3558-94
缺点种类
Kinds of flaws
评级
Classfying
接收标准
Acceptance criteria
裂纹
Crack
不评级或大于Ⅴ
Non-class or greater than class V
不接收
Not accepted
未熔合
Lack of fusion
不评级或大于Ⅴ
Non-class or greater than class V
不接收
Not accepted
未焊透
Incomplete root penetration
不评级或大于Ⅴ
Non-class or greater than class V
不接收
Not accepted
圆形缺点（长宽比小于等于3，包含气孔、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 point
10*10
10*20
10*30
母材厚度Plate thickness
≤10
＞10~15
＞15~25
＞25~50
＞50~100
＞100
圆形缺点个数Number of rotundity flaws
Ⅰ
3
6
9
12
15
18
15
Ⅱ
5
10
15
20
25
30
20
Ⅲ
7
14
21
28
35
42
25
Ⅳ
9
18
27
36
45
54
30
Ⅴ
点数多于Ⅳ（长径尺寸大于t/2）
“Number of point” more than IV (length dimension greater than t/2)
长形缺点（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)
单个长形缺点限值Single limited length- flaws
长形缺点在任意12t焊缝长度内限值Threshold level for length- flaws existing on length as 12t at random
评级
Classification
母材厚度Plate thickness
≤12
＞12~48
＞48
单个缺点尺寸Size of single flaws
Ⅰ
≤4
≤1/3t
≤16
小于t
Not greater than t
Ⅱ
≤6
≤1/2t
≤24
小于1.5t
Not greater than 1.5t
Ⅲ
≤8
≤2/3t
≤32
小于2t
Not greater than 2t
Ⅳ
≤10
≤6/5t
≤40
小于3t
Not greater than 3t
Ⅴ
大于Ⅳ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、未熔合等危害性缺点在CB/T3558-94标准中是不接收，在IACS Rec. 20标准中能够接收一定长度未熔合和未焊透缺点；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. 在两标准中夹渣分级和评价，比如选择厚度为20mm焊缝作缺点评定，在IACS Rec. 20标准中能够接收单个夹渣长度为20mm，在CB/T3558-94标准中II级和III级合格夹渣许可长度为10mm和13mm；间断累计缺点许可长度分别为: 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/T3558-94
3. 通常来讲，船厂或无损检测企业在实际评片中使用合格等级最少为II级（III级合格为船舯部0.6L之外等），所以CB/T3558-94标准缺点评价分级要严于IACS) Rec. 20标准要求。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 curve
CB/T3559-94
母材厚度
Plate thickness
ARL(判废线）
DRL（测长区分线）
MRL（测长线）
≤50
Φ3
Φ3-10dB
Φ3-16dB
＞50
Φ3+2dB
Φ3-6dB
Φ3-12dB
IACS Rec. 20
测长线MRL
评定线
Evaluation Line
大于100%DAC曲线波高（Φ3孔径）
Greater than 100% of DAC curve (Φ3)
回波高度在DAC缺点50~100%之间（Φ3孔径）
Greater than 50% but less than 100% of DAC curve (Φ3)
低于33%DAC曲线波高（Φ3-10dB）
Less than 33% of DAC curve (Φ3-10dB)

表6 / Table 6：
超声波探伤焊缝质量分级
Acceptance criteria for Ultrasonic testing
IACS Rec. 20
CB/T3559-94
回波高度
ECHO Height
接收标准
Acceptance criteria
评级
Classification
单个缺点指示长度
Indicated length for single flaw
在6t或150mm 焊缝长度内
In length of 6t or 150 mm welding seam
Ⅰ
t/3，最小8，最大24
t/3, Min. 8, Max. 24
2t
大于100%DAC曲线回波高度
Greater than 100% of DAC curve
单个缺点最大接收长度t/2或25mm，二者取小者；
Max. length t/2 or 25 mm whichever is the less
Ⅱ
t/2，最小12，最大36
t/2, Min. 12, Max. 36
2.5t
回波高度在DAC缺点50~100%之间
Greater than 50% but less than 100% of DAC curve
单个缺点最大接收长度t或50mm，二者取小者；
Max. length t or 50 mm whichever is the less
Ⅲ
3/4t，最小16，最大48
3/4t, Min. 16, Max. 48
3t
评定认为是裂纹不管回波高度全部是不接收
Indications evaluated to be cracks are unacceptable regardless of ECHO height
Ⅳ
t，最小20，最大60
t, Min. 20, Max. 60
4t
在接头单面焊缝评定认为是未焊透，不管回波高度全部是不接收
Indications evaluated to be lack of root penetration in joints welded from one side are unacceptable regardless of ECHO height
Ⅴ
大于Ⅳ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，依据缺点波高和指示长度及分布状态，把焊缝质量分为Ⅰ~Ⅴ级；高于ARL (判废线）缺点回波均评定为Ⅴ级；低于或等于MRL（测长线）缺点回波可评定为Ⅰ级；超出MRL（测长线）到ARL(判废线）之间缺点回波，据所测定指示长度按分级表评级；As per CB/T3559-94, classifying welding seam quality as class I~V, 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，要求了测长线和评定线回波高度，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 I~V, 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 length
3. 对于缺点评定Acceptance criteria：
1） 在IACS Rec. 20标准中，大于100%DAC曲线回波高度，单个缺点最大接收长度t/2或25mm，二者取小者；在CB/T3559-94标准中，评定为判废不接收；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缺点50~100%之间，单个缺点最大接收长度t或50mm，二者取小者；在CB/T3559-94标准中，据所测定长度评级；比如选择厚度为20mm焊缝作缺点评定，能够接收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%DAC曲线波高（Φ3-10dB）评定为合格，在CB/T3559-94标准中，低于或等于MRL（测长线）缺点回波可评定为Ⅰ级；As per IACS REC 20, less than 33% of DAC curve (Φ3-10dB) could be accepted; as per CB/T 3559-94, ECHO height lower or equal to MRL could be accepted as Class I.
4） 评定认为是裂纹、未焊透、未熔合，二者全部不接收；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. 船厂或无损检测企业通常最少采取CB/T3559-94标准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 testing
IACS Rec. 20

CB/T3958-
表面缺点
Surface discontinuity
接收标准
Acceptance criteria
评定区尺寸
Size for assessment zone
评级
Classification
单个缺点指示长度
Indicated length for single flaw
35*100
Ⅰ
＜0.5
裂纹Crack
不接收Not accepted
Ⅱ
0.5~2.0
未熔合Lack of fusion
不接收Not accepted
Ⅲ
＞2~4
在对接接头单面焊缝未焊透Incomplete root penetration in butt joints welded from one side
不接收Not accepted
Ⅳ
＞4~8
表面气孔
Surface pore
在对接接头上单个气孔直径≤0.25t（角焊缝单个气孔直径≤0.25a)，但最大直径3mm；相邻气孔最小间距为2.5倍直径
Single pore diameter d≤025t¹) for butt welds (d≦0.25a¹) for fillet welds) with Max. diameter 3 mm; 2.5d as Min. distance to adjacent pore.
Ⅴ
＞8
对接接头焊缝咬边Undercut in butt welds
不管多长，但深度≤0.5mm；深度≤0.8mm，最大缺点长度不超出90mm
Depth ≤0.5 mm whatever is the length
Depth ≤0.8 mm with a Max. continuous²) length of 90 mm
不许可缺点Unacceptable flaws
裂纹、未熔合、任何长度大于3mm线状缺点、任何单个直径大于4mm圆形缺点
Cracks, lack of fusion, any length over 3 mm for lined flaws and any dia. over 4 mm for rotundity flaws.

在角焊缝上咬边
Undercut in fillet welds
任何长度，但深度≤0.8mm
Depth ≤0.8 mm whatever is the length
Note:
¹): “t”取焊接板材最小厚度， “a”是焊喉。 “t” is the plate thickness of the thinnest plate and “a” is the throat of fillet weld.
²): 相邻焊缝咬边间距通常小于其中最短咬边长度，均应视作一个连续咬边缺点Adjacent undercuts separated by a distance shorter than the shortest undercut should be regarded as a single continuous undercut.

表7 / Table 7：
1. 评定认为是裂纹、未焊透、未熔合，二者全部不接收；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-标准中，任何长度大于3mm线状缺点、任何单个直径大于4mm圆形缺点，不接收；As per CB/T 3958-, 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，表面气孔能够接收尺寸为在对接接头上单个气孔直径≤0.25t（角焊缝单个气孔直径≤0.25a)，但最大直径3mm；相邻气孔最小间距为2.5倍直径；在CB/T3958-标准中，单个缺点指示长度可接收长度0.5~2.0（II级合格）和＞2~4（III级合格）；As per IACS REC 20, acceptance criteria for single pore diameter d≤0.25t¹) for butt welds (d≦0.25a¹) for fillet welds) with Max. diameter 3 mm; 2.5d as Min. distance to