1-超声波探伤指导书

1、附件八attachment 超声波检测作业指导书guidelines for ultrasonic testing task1一般要求1.1 检测范围1.1.1依据标准jb4730-1994压力容器无损检测。1.1.2 超声检测系指采用a型脉冲反射式超声波探伤仪手工扫查发现内部缺陷，并对其进行等级分类的全过程。检测范围包括压力容器、压力管道以及储罐的原材料和焊缝的超声检测。1.2 检测人员1.2.1 凡从事检测的人员, 都必须经过技术培训,并按照锅炉压力容器无损检测人员资格认可规则(1995)及gb9445进行考核鉴定。1.2.2 取得不同无损检测方法的各技术等级人员，只能从事与该等级相应的无

2、损检测工作，并负相应的技术责任。1.3 探伤仪、探头和系统性能。1.3.1 探伤仪采用a型脉反射式数字式超声波探伤仪,其工作频率范围为1-5mhz，仪器至少在荧光屏满刻度的80范围内呈线性显示。探伤仪应具有0-110db的增益范围，步进级0.1，2.0，6.0db,其精度为任意相邻12db误差在1db以内，最大累计误差不超过1db。水平线性误差不大于1，垂直线性误差不大于5。 其余指标应符合zb y 230的规定。1.3.2 探头1.3.2.1 超声检测选用探头有单直探头、单斜探头和双晶探头。1.3.2.2 晶片有效面积一般不应超过500mm2，且任一边长不应大于25mm。1.3.2.3 单斜

3、探头声束轴线水平偏离角不应大于2,主声束垂直方向不应有明显的双峰。其检测方法应符合zb y 231的规定。1.3.3 超探仪和探头的系统性能1.3.3.1 在达到所探工件的最大检测声程时,其有效灵敏度余量应大于等于10db。1.3.3.2 直探头的远场分辨力应大于等于40db,斜探头的远场分辨力应大于或等于6db。1.4 超声检测方法1.4.1 检测复盖率 检测时，应尽量扫查到工件的整个被检区域，探头的每次扫查复盖率应大于探头直径的15。1.4.2 探头的移动速度 探头的扫查速度不应超过150mm/s。1.4.3 扫查灵敏度 扫查灵敏度至少应比基准灵敏度高6db。1.4.4 耦合剂应采用机油、

4、浆糊、甘油和水等透声性好,且不损伤检测表面和耦合剂。1.4.5 检测面1.4.5.1 检测面和探测范围的确定原则上应保证检查到工件被检部分的整个体积。对于钢板,应检查到整个工件，而对熔接焊缝则应检查到整条焊缝。1.4.5.2 检测面应经外观检查合格，所有影响超声波检测的锈蚀、飞溅和污物都应予以清除，其表面粗糙度应符合检测要求。1.4.5.3 耦合补偿 a.表面粗糙度补偿 在检测和缺陷定量时,应对由表面粗糙度引起的能量损耗进行补偿.1.5 校准 校准应在基准试块上进行，校准中应使超声主声束垂直对准反射体的轴线，以获得稳定和最大的反射信号。1.5.1 仪器校准 在仪器开始使用时，仪器需经检定合格。

5、在使用过程中，每隔三个月至少应对仪器的水平线和垂直线性进行一次测定。1.5.2 探头校准 在探头开始使用时，应对探头进行一次全面的性能校准。测定方法应按zb y231的有关规定进行。1.5.2.1 斜探头校准 使用前,斜探头应至少进行前沿距离、k值、主声束偏离、灵敏度余量和分辨力等的校准。使用过程中，对前沿距离、k值和声束偏离应在每一个工作日检查一次。1.5.2.2 直探头校准 直探头的始脉冲占宽、灵敏度余量和分辨力应在开始使用时，及每隔一个月检查一次。1.5.3 仪器和探头系统的复核1.5.3.1 复核时机 每次检测前均应对扫描线、灵敏度进行复核，遇有下述情况应随时对其进行重新核查: a.校

6、准后的探头和耦合剂发生改变时; b.开路电压波动或者检测者怀疑灵敏度有变化时; c.连续工作4h以上; d.工作结束时。1.5.3.2 距离一波幅曲线的复核 复核时,曲线上任何一点幅度下降2db，则应对上一次以来所有的检测结果进行复检；如幅度上升2db，则应对所有的记录信号进行重新评定。1.5.4 注意事项 校准、复核和线性检验时，任何影响仪器线性的控制器(如抑制)应处于最低水平上。1.6 报告及验收标记1.6.1 检测报告至少应包括以下内容: a.委托单位、报告编号； b.工件名称、编号、材质、热处理状态、检测表面的粗糙度； c.探伤仪、探头、试块和检测灵敏度； d.超声检测区域应在草图上予

7、以标明，如有因几何形状限制而检测不到的部位,也应加以说明； e.缺陷的类型、尺寸、位置和分布； f.检测结果及缺陷等级评定； g.检测人员和责任人员签字及其技术资格；h.检测日期。2焊缝超声波检测2.1 检测范围和一般要求 本条规定了焊缝缺陷的超声检测方法。 本条适用于母材厚度为8-300mm全焊透熔化焊对接焊缝的超声检测。 本条不适用于铸钢及奥氏体钢焊缝,外径小于159mm的钢管对接焊缝，内径小于等于200mm的管座角焊缝,也不适用于外径小于250mm或内、外径之比小于80的纵向焊缝检测。2.2 检测准备2.2.1 检测面 a.压力容器焊缝检测一般采用一种k值探头、利用一次反射法在焊缝的单面

8、双侧对整个焊接接头进行检测。当母材厚度大于46mm时，采用双面双侧的直射波检测。对于要求比较高的焊缝，根据实际需要也可将焊缝余高磨平，直接在焊缝上进行检测。 b.检测区域的宽度应是焊缝本身，再加上焊缝两侧各相当于母材厚度30的一段区域，这个区域最小10mm。 c.探头移动区应清除焊接飞溅、铁屑、油垢及其它杂质。检测表面应平整光滑，便于探头的自由扫查，其表面粗糙度ra应为6.3m，一般应进行打磨。 (1)采用一次反射法或串列式扫查检测时,探头移动区应不小于1.25p: p=2tk 或 p=2ttg式中: p-跨距,mm； t-母材厚度,mm； k-探头k值； -探头折射角,()。 (2) 采用直

9、射法检测时，探头移动区应不小于0.75p。 d.去除余高的焊缝，应将余高打磨到与邻近母材平齐。 保留余高的焊缝，如焊缝表面有咬边、较大的隆起和凹陷等也应进行适当的修磨，并作圆滑过渡以免影响检验结果的评定。2.2.2 探头k值(角度) a.斜探头的k值(角度)选取可参照表1-1的规定。条件允许时,应尽量采用较大k值探头。表1-1 推荐应用的斜探头k值板 厚 t mmk 值8252546461201203003.02.0(7260)2.51.5(6856)2.01.0(6045)2.01.0(6045) b.串列式扫查,推荐选用两个k1的探头实际折射角相差不应超过2,探头前沿长度相差应小于2mm.

10、为便于探测厚焊缝坡口边缘未熔合缺陷,亦可选用两个不同k值的探头,但两个探头k值均应在0.71.43范围内。2.2.3 母材的检测 斜探头扫查声束通过的母材区域，应先用直探头作检测，以便探测是否有影响斜探头检测结果的分层或其他种类缺陷存在。该项检测仅作记录，不属于对母材的验收检测。母材检测的规程要点如下: a.方法: 接触式脉冲反射法，采用频率25mhz的直探头，晶片直径10-25mm； b.灵敏度:将无缺陷处第二次底波调节为荧光屏满幅的100； c.记录:凡缺陷信号幅度超过荧光屏满幅20的部位，应在工件表面作出标记，并予以记录。2.3 距离-波幅曲线的绘制2.3.1 距离-波幅曲线按所用探头和

11、仪器在试块上实测的数据绘制而成，该曲线由评定线、定量线和判废线组成。评定线与定量线之间(包括评定线)为区，定量线与判废线之间(包括定量线)为区，判废线及其以上区为区。2.3.2 距离-波幅曲线的灵敏度选择 a.壁厚为8-120mm的焊缝，其距离-波幅曲线灵敏度按表1-2的规定。表1-2 距离-波幅曲线的灵敏度试块型式板厚 mm评定线定量线判废线csk iiia 81515464612016-12db16- 9db16- 6db16-6db16-3db1616+2db16+5db16+10db b.检测横向缺陷时,应将各线灵敏度均提高6db。c.工件的表面耦合损失和材质衰减应与试块相同。d.扫查

12、灵敏度不低于最大声程处的评定线灵敏度。2.4 检测方法2.4.1 平板对接焊缝的检测 a.为检测纵向缺陷，原则上采用一种k值探头或两种k值探头在焊缝的单面双侧进行检测。母材厚度大于46mm时，采用双面双侧检测,如受几何条件限制，也可在焊缝双面单侧采用两种k值探头进行检测，斜探头应垂直于焊缝中心线放置在检测面上，作锯齿型扫查，探头前后移动的范围应保证扫查到全部焊缝截面及热影响区。在保持探头垂直焊缝前后移动的同时，还应作1015的左右移动。当壁厚大于40mm且单侧坡口角度小于5时，应采用串列式检测。 b.为检测焊缝及热影响区的横向缺陷应进行平行和斜平行扫查。检测时，可在焊缝两侧边缘使探头与焊缝中心

13、线成1020作斜平行扫查。焊缝余高磨平时，可将探头放在焊缝及热影响区上作两个方向的平行扫查。焊缝母材超过100mm时，应在焊缝的两面作平行扫查或者采用两种k值探头(k1和k1.5或k1和k2并用)作单面两个方向的平行扫查；必要时亦可用两个k1探头作串列式扫查。 c.为确定缺陷的位置、方向和形状，观察缺陷动态波形和区分缺陷信号或伪信号，可采用前后、左右、转角、环绕等四种探头基本扫查方式。2.5缺陷定量检测2.5.1 灵敏度应调到定量线灵敏度。2.5.2 对所有反射波幅超过定量线的缺陷，均应确定其位置，最大反射波幅和缺陷当量。2.5.3 缺陷定量应根据缺陷最大反射波幅确定缺陷当量直径或缺陷指示长度

14、l。a.缺陷当量直径，用当量平底孔直径表示，主要用于直探头检测，可采用公式计算，距离一波幅曲线和试块对比来确定缺陷当量尺寸。 b.缺陷指示度长度l的测定采用以下方法：（1）缺陷反射波只有一个高点，且位于区时，用6db法测其指示度。（2）当缺陷反射波峰值起伏变化，有多个高点，且位于区时，应以端点6db测其指示度。（3）当缺陷反射波峰位于区，如认为有必要记录时，将探头左右移动，使波幅降到评定线，以此测定缺陷指示度。2.6 缺陷评定2.6.1超过评定线的信号应注意其是否具有裂纹等危害性缺陷特征，如有怀疑时，应采取改变探头k值、增加检测面、观察动态波型并结合结构工艺特征作判定，如对波型不能判断时，应辅

15、以其它检测方法综合判定。2.6.2 缺陷指示长度小于10时按5计。2.6.3 相邻两缺陷在一直线上，其间距小于其中较小的缺陷长度时，应作为一条缺陷处理，以两缺陷长度之和作为其指示长度（不考虑间距）。2.7 缺陷等级评定按jb4730-1994第9.1.8条执行3钢板超声检测3.1 检测范围和一般要求本条适用于板厚为6250mm的板材的超声检测。奥氏体钢板材的超声检测也可参照本条执行。3.2 探头选用探头的选用应按表3-1的规定进行。3.3 标准试块3.3.1 用双晶直探头检测壁厚小于或等于20mm的钢板时，采用标准试块如图3-1所示。3.3.2用单直探头检测板厚大于20mm的钢板时，标准试块应

16、图3-2和表3-2的规定。试块厚度应与被检钢板厚度相近。3.4 检测灵敏度3.4.1板厚小于或等于20mm时，用图3-1所示的试块将工件等厚部位第一次波高度调整到满刻度的50%，再提高10db作为检测灵敏度。3.4.2 板厚大于20mm时，应将图3-2所不的试块平底孔第一次反射波高调整到满刻度的50%作为检测灵敏度。表3-1 探头选用板 厚mm采用探头公称频率探头晶片尺寸双晶直探头单晶直探头020双晶直探头5mhz晶片面积不小于150mm2-20250单晶直探头2.5mhz- 圆晶片直径为1425mm，或方晶片面积不小于200mm2表3-2 试块编号被检钢板厚度检测面到平底孔的距离 s试块厚度

17、 t123456204040606010010016016020020025015305090140190204065110170220全部6.3403456789108404048423630241915124040840图3-1 板厚小于或等于20mm双晶直探头检测用试块3.3a 0.1 a5ts100100图3-2 板厚大于20mm单直探头检测用试块3.4.3 板厚大于60mm时，也可取钢板无缺陷的完好部位的第一次底波来校准灵敏度，其结果应与3.4.2条的要求相一致。3.5 检测方法3.5.1 检测面可选钢板的任一轧制平面进行检测。若检测人员认为需要或设计上有要求时，也可对钢板的上下两轧

18、制平面分别进行检测。3.5.2 扫查方式 100 100 100 压延方向(a)剖口预定线100%扫查区 (b)图3-3 探头扫查示意图a、探头沿垂直于钢板压延方向，间距为100的平行线进行扫查。在钢板剖口预定线两侧各50(当板厚超过100时，以板厚的一半为准)内应作100%扫查，扫查示意图如图3-3。b、根据合同、技术协议书或图样的要求，也可进行其它形式的扫查。3.6 缺陷记录3.6.1 在检测过程中，发现下列三种情况之一者即作为缺陷：a、缺陷第一次反射波（f1）波高大于或等于满刻度的50%，即f150%者。b、当底面第一次反射波（b1）波高未达到满刻度，此时，缺陷第一次反射波（f1）波高与

19、底面第一次反射波之比大于或等于50%，即b1100%，而f1/b150%者。c、当底面第一次反射波（b1）波高低于满刻度的50%，即b150%者。3.6.2 缺陷的边或指示长度的测定方法a、 检出缺陷后，应在它的周围继续进行检测，以确定缺陷的延伸。b、 用双晶直的探头确定缺陷的边界或指示长度时，探头的移动方向应与探头的声波分割面相垂直，并使缺陷波下降到检测灵敏度条件下荧光屏满刻度的25%或使缺陷第一次反射波高与底面第一次反射波高之比为50%。此时，探头中心的移动距离即为缺陷的指示长度，探头中心点即为缺陷的边界点。丙种方法测行的结果以较者为准。c、 用单直探头确定缺陷的边界或指示长度时，移动探头

20、，使缺陷波第一次反射波高下降到检测灵敏度条件下荧光屏满刻度的25%或使缺陷第一次反射波与底面第一次反射波高比为50%.此时，探头中心移动距离即为缺陷的指示长度，探头中心即为缺陷的边界点。两种方法测行的结果以较严重者为准。d、 确定8.1.6.1c条缺陷的边界或指示长度时，移动探头，使底面第一次反射波升高到荧光屏满刻度的50%。此时，探头中心移动距离即为缺陷的指示长度。探头中心点即为缺陷的边界点。e、 当采用第二次缺陷波和第二次底波来评定缺陷时，检测灵敏度应以相应的第二次反射波来校准。3.7 缺陷的评定方法3.7.1 缺陷指示长度的评定规则一个缺陷按其指示的最大长度作为该缺陷的指示长度。3.7.

21、2 单个缺陷指示面积的评定规则 a、一个缺陷按其指示的最大面积作为该缺陷的单个指示面积。当其小于表3-3的规定时，可不作记录。 b、多个缺陷其相邻间距小于100或间距小于相邻小缺陷的指示长度(取其较大值)时，其各块缺陷面积之和作为单个缺陷指示面积。3.7.3 缺陷面积占有率评定规则 在任一1m1m检测面积内，按缺陷面积所占的百分比来确定。表3-3 等级单个缺陷指示长度单个缺陷指示面积2 在任-1m1m检测面积内存在的缺陷面积百分比 % 以下单个缺陷指示面积不记 2608012015025501001003451091525253.8 钢板缺陷条块等级评定3.8.1 钢板缺陷等级划分按jb473

22、0-94第8.1。1general requirements1.1 scope of testing1.1.1 the guidelines are written in accordance with jb4730-1994 nondestructive testing of pressure equipments.1.1.2 ultrasonic testing refers to the whole process that inner defects are found by scanning manually using an a-model pulse reflection ult

23、rasonic flaw detector and then classified into grades. the scope of testing includes ultrasonic testing of raw materials and weld of pressure equipments, pressure pipes and store tanks.1.2 ndt personnel1.2.1 personnel engaging in ndt should have received technical trainings and passed qualification

24、tests in accordance with rules of certification for ndt personnel on boiler pressure equipments (1995) and gb9445 national standard.1.2.2 technicians who have passed certain levels of ndt qualification tests should perform ndt tasks equivalent to that level and be liable to such responsibilities.1.3

25、 flaw detector, probe and system performance1.3.1 flaw detectorfor a digital ultrasonic flaw detector of a-model pulse reflection with 1-5mhz working frequency, the apparatus should display linearly in at least 80% of full scale of the fluorescent screen. the flaw detector should has a 0-110db gain

26、range with stepping increments of 0.1，2.0 and 6.0db. the precision of the flaw detector is two arbitrary points that distance 12db with error within 1db and the maximum accumulative error not exceeding 1db. its horizontal linearity error is not exceeding 1% and vertical linearity error not exceeding

27、 5%. the other criterions should meet requirements of zb y 230.1.3.2 probe1.3.2.1 probes of ut include single straight beam probe, single angle probe and double crystal probe.1.3.2.2 generally the effective area of wafer should not exceed 500mm2, and the length of either side should not exceed 25mm.

28、1.3.2.3 for the single angle probe, the angle by which the horizontal ultrasonic beam axis deviates from the probe axis should be less than 2. main beam at vertical direction should not produce obvious double peaks. the testing method should meet requirements of zb y 231.1.3.3 system performance of

29、the ultrasonic flaw detector and probe1.3.3.1 when the detector reaches its maximum beam path length of the tested workpiece, the remaining effective sensitivity should exceed or equal to 10db.1.3.3.2 far-field resolution of the straight beam probe should exceed or equal to 40db, and far-field resol

30、ution of the angle probe should exceed or equal to 6db.1.4 ultrasonic testing method1.4.1 percentage of scan coverage when testing，the whole area to be inspected should be scanned. every scan of the probe should cover more than 15% of the probes diameter.1.4.2 scan speed of the probe scan speed of t

31、he probe should not exceed 150mm/s。1.4.3 scan sensitivity scan sensitivity should be at least 6db higher than norm sensitivity.1.4.4 couplants couplants that have good sound transparency and do not damage the surface tested should be used, such as engine oil, paste, glycerol and water, etc.1.4.5 tes

32、ted surface 1.4.5.1 in principle, surface and area being tested should be guaranteed to cover the whole volume of the tested part of the workpiece. to steel plate, the whole workpiece should be inspected, while to fusion jointing weld, the whole weld should be inspected.1.4.5.2 the tested surface sh

33、ould pass appearance check. all surface rusts, splashes and contaminants that would affect ut operation should be removed. surface roughness should meet requirements of the test. 1.4.5.3 coupling compensation a. compensation because of surface roughness when testing and quantification of defects, en

34、ergy waste caused by roughness of the tested surface should be compensated.1.5 calibration calibration should be done on reference test block. in calibrating, main sound beam should aim vertically at the axis of the reflecting block to obtain stable and maximal reflected signals.1.5.1 calibration of

35、 instrument instrument should be certified for acceptance before use. during service period, horizontal and vertical linearity of the instrument should be checked at least every three months.1.5.2 calibration of probe probe should be calibrated comprehensively for performance in accordance with requ

36、irements of zb y231.1.5.2.1 calibration of squint angle probe squint angle probe should be, before use, at least calibrated for leading edge distance, “k” value, main beam deviation, remaining sensitivity and resolution, etc. during service period, leading edge distance, “k” value and main beam devi

37、ation should be inspected in each workday.1.5.2.2 calibration of straight beam probe before use and at every other month, the straight beam probe should be checked for occupying width of initial pulse, remaining sensitivity and resolution.1.5.3 rechecking of the instrument and probe 1.5.3.1 rechecki

38、ng occasions scan line and sensitivity should be rechecked before each test. if the following circumstances occur, the system should be rechecked again at any time. a. changes occur to the probe and the couplant that have been calibrated; b. voltage of open circuit fluctuates or tester doubts about

39、its sensitivity; c. continuous working over 4h; d. completion of testing.1.5.3.2 rechecking the distance-amplitude curve in rechecking, if amplitude at any point on the curve declines by 2db, all test results starting from last inspection should be rechecked; if amplitude rises by 2db，all recorded s

40、ignals should be reassessed .1.5.4 attentionsin calibration, recheck and linearity test，any influence to the linearity of the equipment caused by controllers, such as suppressers, should be kept at the minimum level.1.6 reports and acceptance 1.6.1 a report should at least include the following item

41、s:a. client, report number；b. workpieces name, serial number, materials, heat-treated condition and roughness of the tested surface；c. flaw detector, probe, test block and test sensitivity;d. area of ut should be marked on the draft. parts impossible to be inspected because of limitation on geometry

42、 should be noted on the draft;e. type of defects, size, location and distribution；f. test results and defect grade evaluation;g. test personnel, responsible personnel and their technical qualifications;h. test date.2 ultrasonic testing of welds2.1 scope of testing and general requirementsthe guideli

43、nes stipulate the ultrasonic testing method of welding defects. the guidelines are applicable to the ultrasonic testing of fusion butt-jointed through welds whose thickness of base material is 8-300mm. the guidelines are not applicable to the ultrasonic testing of following welds: welds of cast stee

44、ls and austenite steels, welds of butt-jointed steel pipelines with outer diameter less than 159mm, fillet welds of pipe saddles with inner diameter less than or equal to 200mm, longitudinal welds with outer diameter less than 250mm or ratio of outer and inner diameters less than 80%.2.2 test prepar

45、ation2.2.1 test surface a. the testing of the pressure vessel welds usually adopts a “k” value probe and the entire welded joint is inspected by one reflection technique on both sides of single surface of the weld. if the thickness of the base material exceeds 46mm, the weld is tested by normal inci

46、dence on both sides of the double surfaces. for the weld with stricter requirements, the excess base metal on the welded surface may be grinded smooth if needed and be tested directly on the weld.b. the width of the test area should be the weld itself plus an area at both sides of the weld that equa

47、ls to 30% thickness of the base metal. such area should be at least 10mm.c. welding splashes, iron chippings, oil crusts and other impurities should be removed away from the probe movement area. the test surface should remain smooth for the probe to scan freely. surface roughness “ra” should be 6.3m

48、. usually, polishing is necessary. (1) in reflection or tandem scanning, probe movement area should be no less than 1.25p, while: p=2tk or p=2ttgwhich: p- skip distance, mm； t-thickness of the base metal, mm； k- “k” value of the probe; - refraction angle of the probe, ()。 (2) in normal incidence tes

49、ting, probe movement area should be no less than 0.75p. d. excess welding metal should be removed and grinded to the same level with adjacent base metal. welds whose excess weld metal need to be preserved should be grinded accordingly, if undercuts, larger humps and pits exist on the welded surface.

50、 and smooth transition on the surface should be guaranteed so that these surface irregularities would not affect test results.2.2.2 “k” value of the probe(angle) a. refer to table 1-1 for the selection of “k” values (angle) of the squint angle probe. select a probe with greater “k” value when condit

51、ions permit.table 1-1 recommended “k” value of squint angle probe plate thickness t mmk 8252546461201203003.02.0(7260)2.51.5(6856)2.01.0(6045)2.01.0(6045)b. for tandem scan, two “k1” probes whose actual refraction angles differ no more than 2are recommended. leading lengths of the probes should diff

52、er less than 2mm. to facilitate detection of defects caused by incomplete fusion at the edge of groove of thick weld, probes with different “k” values may be selected, but their “k” values should be among the range of 0.71.43.2.2.3 testing of base materialsthe base material through which sound beam

53、transmitted using squint angle probe should be pre-tested first by straight beam probe in order to find out whether delamination or other types of defects that could affect testing results of squint angle probe exist. the pre-test is only for recording. it does not belongs to acceptance criteria of

54、base materials. the essentials in the testing regulation of base materials are as follow:a. method: contact-type pulse reflection using straight beam probe of 25mhz working frequency with wafer of 10-25mm diameter.b. sensitivity: the second bottom wave at non-defect part is adjusted to 100% of the fluorescent screen. c. note: any part whose amplitude of defect signal exceed 20% of full amplitude of the fluorescent screen should be marked on the weldment surface and noted down.2.3 plotting distance-amplitude curve2.3.1