西柏坡电厂扩建工程2锅炉型号B＆W-1025/18.3-M,其尾部顶棚过热器前部分设计为110根(?)42mm×5mm膜式管排.锅炉安装完毕进行风压试验时,焊点处发现两处漏风,确认为径向贯穿裂纹,周向长度10～15mm(图1).1 探伤方法及仪器试块的选择由图1可见,在应力最集中的焊点处,裂纹由管材外表向内沿伸,且有时隐藏在焊点下侧.受几何位置限制,难于作射线检验,加之表面凹凸不平,着色及磁粉检验也难达到目的,所以考虑用超声检验.仪器选用CTS-22型超声波探伤仪.探头晶片尺寸4mm×6mm,前沿l=4.5mm,K=1.5(保证一、二次波扫查点焊处覆盖的管材),频率4MHz,探头接触面修磨成与(?)42mm圆弧接近.耦合剂为水质浆糊.试块型号为HD-1(图2),图中三孔均为(?)1mm×4mm孔,用此试块测定前沿,调整扫描比例.自制对比试块见图3,选用同材质同规格的备用管,在其表面锯一3mm深垂直槽,然后在其表面焊一δ5mm Xibaipo power plant expansion project 2 boiler model B & W-1025 / 18.3-M, the tail of the front part of the superheater is designed to be 110 (?) 42mm × 5mm film tube row. Boiler installation is carried out wind pressure test, the solder joints Found two air leakage, confirmed as radial through the cracks, the circumferential length of 10 ~ 15mm (Figure 1) .1 flaw detection method and the choice of test block shown in Figure 1, the stress concentration of the solder joints, cracks by the pipe surface Inward extension, and sometimes hidden in the solder joints under the constraints by the geometric position, difficult to make ray inspection, combined with uneven surface, coloring and magnetic particle inspection is also difficult to achieve the goal, so consider using ultrasonic testing. Instrument Selection CTS-22 Ultrasonic Flaw Detector The probe chip size is 4mm × 6mm, the leading edge is l = 4.5mm, K = 1.5 (to ensure the primary and secondary wave scanning spot welding pipe cover), the frequency of 4MHz, 42mm arc close. Coupling agent for the water quality paste. Block type HD-1 (Figure 2), the figure three holes are (?) 1mm × 4mm hole, using this test block to determine the front, adjust the scan ratio. Compare the test block shown in Figure 3, the choice of the same material with the specifications of the spare pipe saw a 3mm deep vertical groove on the surface, and then welded a δ5mm