在高温高压H2下稳态运行期间，溶解在钢制压力容器厚壁中的氢，会导致亚临界裂纹缓慢扩展，以及停堆和启动期间的不稳定灾难性断裂。这种行为在第2节中有定义。因此，对最低加压温度（MPT）和适用性（FFS）的现代断裂力学评估必须包括H对亚临界和不稳定内部氢辅助开裂（IHAC）的有害影响。有两种方法正在起草阶段，以制定满足这一需求的标准程序；API 934-F推荐规程和ASME/API 579的WRC公告562基础。本技术报告的目的是建立必要的技术基础，以实现和验证这些最佳实践，从而量化氢对厚壁加氢处理反应器（a）MPT和（b）FFS的影响。 该方法包括两部分。第1部分强调了两种主要H型开裂性能的临界评估和收集；在缓慢上升的应力强度（KIH）下，亚临界H裂纹开始的临界应力强度，以及由H（KIC-H）促进的不稳定灾难性解理样裂纹扩展开始的临界应力强度。第2部分重点介绍了使用这些数据定量预测MPT的方法，该MPT可防止停堆和启动期间H开裂。这两部分的总和、经过验证的大量IHAC数据和基于科学的工程分析，建立了一个单一的技术基础，可以一致地纳入API 934-F和API/ASME 579控制H裂纹的推荐做法中。第3节记录了大量KIHand KIC Hdata，这些数据保守地描述了2¼Cr-1Mo焊接金属和基板中的IHAC。 记录了关键变量的影响，包括热暴露后FATT的回火脆化程度、总H浓度和应力温度。KIHdata是三类钢纯度的总和。第3节还介绍了美国石油学会最近赞助的一项研究的结果，该研究建立了与钒改性铬钼钢MPT和FFS评估相关的材料性能数据。第4节使用第3节中提供的断裂力学数据，为MPT和FFS评估提供技术基础。基于裂纹尖端H浓度相似性的基本概念，有效地模拟了H浓度、温度和裂纹体几何形状对KIHare的影响。第5节列出了MPT确定的拟议架构，该架构由稳定IHAC和不稳定快速断裂标准定义。 每个标准有三个级别的评估。1级是最简单、最保守的方法，而3级是最复杂、最不保守的程序。

Hydrogen, dissolved in the thick wall of a steel pressure vessel during steady-state operation in elevated temperature, high-pressure H2, can cause both slow-subcritical crack advance as well as unstable-catastrophic fracture during shutdown and startup. This behavior is defined in Section 2. It follows that modern fracture-mechanics assessments of the minimum pressurization temperature (MPT) and fitness for service (FFS) must include the deleterious effect of H on both subcritical and unstable internal hydrogen assisted cracking (IHAC). Two approaches are in draft stage to develop standard procedures that address this need; an API 934-F recommended practice and a WRC Bulletin 562 basis for ASME/API 579.The objective of this technical report is to establish the technical basis necessary to enable and validate these best practices for quantifying the effects of hydrogen on (a) the MPT, and (b) FFS of a thick wall hydroprocessing reactor. The approach entails two parts.Part 1 emphasizes critical assessment and collection of two primary H-cracking properties; the threshold stress intensity for the onset of subcritical H cracking under slow-rising stress intensity (KIH), and the critical stress intensity for the onset of unstable-catastrophic cleavage-like crack growth promoted by H (KIC-H).Part 2 focuses on the methods to use these data to quantitatively predict an MPT that precludes H cracking during shutdown and startup. The sum of these two parts, validated-extensive IHAC data, and science-based engineering analysis, establishes a single technical basis that can be consistently incorporated in API 934-F and API/ASME 579 recommended practices to control H cracking.Section 3 documents extensive KIHand KIC-Hdata that conservatively characterize IHAC in 2¼Cr-1Mo weld metal and base plate. The effects of critical variables are documented, including the degree of temper embrittlement in terms of the FATT after thermal exposure, total H concentration, and stressing temperature. KIHdata are aggregated for three classes of steel purity. Section 3 also presents results from a recent API-sponsored study that established the material-property data relevant to MPT and FFS assessment for V-modified Cr-Mo steel.Section 4 develops the technical basis for MPT and FFS assessments using the fracture-mechanics data presented in Section 3. The effects of H concentration, temperature, and cracked body geometry on KIHare effectively modeled based on the fundamental concept of crack tip H concentration similitude.Section 5 lays out the proposed architecture for the MPT determination, which is defined by both stable IHAC and unstable fast fracture criteria. There are three levels of assessment for each criterion. Level 1 constitutes the simplest and most conservative method, while Level 3 is the most complex procedure and is the least conservative.