本公告涵盖了可用于服务适用性（FFS）服务评估的各种焊接部件的一致残余应力估计值的制定，以及执行局部焊后热处理（L-PWHT）的推荐程序的制定。使用有限元方法进行了大量残余应力和局部焊后热处理分析。主要研究结果总结如下。全厚度残余应力分布可分解为三个基本部分:全厚度薄膜；全厚度弯曲；通过厚度自平衡。 组合峰值残余应力值可根据材料的屈服强度进行缩放。薄膜和弯曲部件主要由关节约束条件决定，包括平移约束和旋转约束条件。管道壁厚和壁厚与管道半径之比是两个重要参数，它们决定了环焊缝在环向上给定净收缩力下的实际截面弯矩量。自平衡部分主要由焊接工艺相关参数控制，如完成焊接的焊道总层数、接头结构和焊道沉积顺序的数量。 尽管残余应力分布的自平衡部分可能在板或管壁厚度上表现出复杂的变化，但FFS评估中使用的断裂力学处理表明，只有这种变化的最低阶近似值才是重要的。回火珠、热影响区相变和其他小尺度现象主要导致高阶变化。经证明，残余应力分解技术同样适用于不同的焊接结构，如缝焊、接管到容器的焊接、补焊。已为环焊缝、缝焊、补焊、搭接角连接焊缝和接管焊缝生成了贯穿厚度的残余应力分布（在文献中也称为剖面）。 横向残余应力（垂直于焊缝）分布对服务适用性评估特别重要，也可能与纵向残余应力（平行于焊缝）的一些贯穿厚度分布特征唯一相关。已经开发了参数方程，可用于自由流速度评估，以产生整个厚度的轴向残余应力分布，其大小由材料的屈服强度来衡量。如果部件在使用前进行了水压试验，则可以实现残余应力整体幅度降低的额外好处。 水压试验前后，残余应力分布特征基本相同。这表明，在水压试验后，除了残余应力的大小根据接头几何形状和水压试验条件而减小外，可使用与焊接状态相同的函数形式来近似整个厚度分布。在热应力和残余应力降低方面，为L-PWHT提供了详细的观察结果和建议。出于FFS目的，全厚度残余应力分布的函数形式与as下的相同- 只要满足第5.3节中提出的要求，焊接条件可用于近似焊接区域内局部焊后热处理后的残余应力分布。然而，必须考虑在距离焊缝一定距离处产生的附加残余应力。

The development of consistent residual stress estimates for various welded components that may be used in a Fitness-For-Service (FFS) service assessment and the development of recommended procedures for performing local post-weld heat treatment (L-PWHT) are covered in this Bulletin. A large number of residual stress and local PWHT analyses using the finite element method were carried out. The major findings are summarized as follows.The through-thickness residual stress distributions can be decomposed into three basic parts: through-thickness membrane; through-thickness bending; and through-thickness self-equilibrating. The combined peak residual stress value may be scaled by the yield strength of material. The membrane and bending components are dominated by joint restraint conditions in terms of translational restraint and rotation restraint conditions. The pipe wall thickness and thickness to pipe radius ratio serve as two important parameters determining the actual amount of sectional bending moment under a given net shrinkage force of a girth weld in the hoop direction. The self-equilibrating part is dominated by welding procedure related parameters such as the total layers of weld passes to complete weld, joint configuration, and the number of weld pass deposition sequences. Although the self-equilibrating part of the residual stress distributions can exhibit a complex variation over plate or pipe wall thickness, the fracture mechanics treatment used in an FFS assessment indicates that only the lowest order approximation of such variations is important. Temper bead, HAZ phase change, and other small scale level phenomena mostly contributes to a higher order variations. The residual stress decomposition technique is shown proven to be equally applicable for different weld configurations such as seam welds, nozzle to vessel welds, repair welds. Through-thickness residual stress distributions (also referred as profiles in literature) have been generated for girth welds, seam welds, repair welds, lap fillet attachment welds and nozzle welds. The transverse residual stress (perpendicular to weld) distributions, which are of particular interest to fitness for service assessment, may also be uniquely related to some of the through-thickness distribution characteristics of the longitudinal residual stresses (parallel to weld). Parametric equations have been developed that can be used in an FFS assessment to generate a through-thickness axial residual stress distribution with the magnitude scaled by yield strength of the material. If a component is subjected to hydro proof test before service, additional benefits in the form of an overall magnitude reduction in the residual stresses may be realized. The residual stress distribution characteristics remain essentially the same both before and after hydro proof tests. This suggests the same functional form used for the as-welded condition may be used to approximate the through-thickness distribution after hydro proof test, except the magnitude in residual stress is reduced depending up joint geometry and hydro proof test conditions.Detailed observations and recommendations are provided for L-PWHT in in terms of both thermal stress and residual stress reductions. For FFS purposes, the same functional form of the through-thickness residual stress profile as that under as-welded conditions can be used to approximate the residual stress profile after local PWHT within the weld area for most of cases investigated, as long as the requirements proposed in Section 5.3 are satisfied. However, considerations must be given to the additional residual stress generated at some distance away from the weld.