The new generation pillow plate heat exchanger (PPHX) is a type of PHXs with a complex wavy structure with desirable thermal-hydraulic characteristics. For the main structure of PPHX, edge welding joints are usually a common and economical design. However, the stress concentration and presence of corrosive media often lead to premature failure of welding structure. In this study, the leakage failure of PHX after 80,000 hours of service was evaluated. The crack at the edge joints of corrugated 316L steel plates was detected by dye permeability detection. The failure of welding joints was studied by optical microscope, scanning electron microscope(SEM), EBSD and X-ray diffraction(XRD). The corrosion product was observed only at inside of the edge joints. The mud pattern morphology and EDS analysis of high Cl ion concentration(2.87 wt.%) on fracture surface revealed the stress corrosion cracking mechanism. Chloride and hydrogen ions were enriched as an occluded cell mechanism on the narrow gap between plates. The carbide precipitated on the grain boundary of the HAZ during the welding process, which initiates cracking under the crevice corrosion environment. Based on the studies carried out, a structure modification welding without narrow gap, duplex or ferrite stainless steel replace the 316L stainless steel, periodic inspection and strict deionization of cooling water were suggested to eliminate such failures.

新一代枕板式热交换器（PPHX）是一种具有复杂波浪结构且具有理想的热工液压特性的PHX。对于PPHX的主要结构，边缘焊接接头通常是一种常见且经济的设计。但是，应力集中和腐蚀性介质的存在通常会导致焊接结构过早失效。在这项研究中，评估了80,000小时的服务后PHX的泄漏故障。通过染料渗透性检测来检测波纹316L钢板的边缘接缝处的裂纹。通过光学显微镜，扫描电子显微镜（SEM），EBSD和X射线衍射（XRD）研究了焊接接头的失效。仅在边缘接头的内部观察到腐蚀产物。高Cl离子浓度（2.87 wt。％）的泥浆形态和EDS分析 ％）在断裂表面上揭示了应力腐蚀开裂的机理。氯离子和氢离子作为富集的细胞机制富集在板之间的狭窄缝隙上。在焊接过程中，碳化物沉淀在热影响区的晶界上，从而在缝隙腐蚀环境下引发裂纹。在进行的研究的基础上，建议采用无窄缝隙，双相或铁素体不锈钢代替316L不锈钢的结构变型焊接，定期检查和对冷却水进行严格的去离子处理来消除此类故障。在缝隙腐蚀环境下会引发裂纹。在进行的研究的基础上，建议采用无窄缝隙，双相或铁素体不锈钢代替316L不锈钢的结构变型焊接，定期检查和对冷却水进行严格的去离子处理来消除此类故障。在缝隙腐蚀环境下会引发裂纹。在进行的研究的基础上，建议采用无窄缝隙，双相或铁素体不锈钢代替316L不锈钢的结构变型焊接，定期检查和对冷却水进行严格的去离子处理来消除此类故障。