过去，压力容器中的开口已根据面积置换规则进行加固。这样设计的船只总体上表现令人满意；然而，在压力容器出现问题的相对较少的情况下；这些问题通常与喷嘴或开口有关。在过去几年的工作之前，人们对压力容器中喷嘴的应力水平、抗疲劳载荷能力和最大压力能力只有非常粗略的了解。 压力容器设计中使用更高强度材料和更高标称应力的趋势，以及具有极高可靠性要求的核容器的出现，使得人们更加需要更好地了解压力容器中加固开口的性能。 鉴于这一需要，压力容器研究委员会加强开口小组委员会赞助了一项广泛的实验和分析工作计划，旨在确定压力容器中加强开口的行为，同时考虑内部压力和外部荷载的影响。J.L.Mershon总结了这项工作，截至出版时。 本报告涵盖了压力容器加固开口整体问题的一个阶段；具体而言，开发了球形壳体中承受内压的径向喷嘴的设计程序。 设计程序旨在为球形容器中的径向喷嘴、半球形封头、复曲面封头定义可接受的加强细节，前提是开口位于球形截面中，与环形截面足够远，且椭圆形封头位于中心截面。如果需要加固，则假定加固与壳体是连续的，这与“焊接”衬垫不同。由于极限分析用于确定设计程序，因此隐含的假设是，壳体和焊缝金属的材料具有延展性，例如，在容器可能加载的所有温度下，能够承受复杂应力场中的局部应变的百分之几。

In the past, openings in pressure vessels have been reinforced according to the area-replacement rule. Vessels so designed have, by and large, performed satisfactorily; however, in the relatively few cases where problems have developed in pressure vessels; those problems have often been associated with the nozzles or openings. Prior to the work of the past few years, the stress levels, fatigue loading resistance, and maximum pressure capacities of nozzles in pressure vessels were known only very roughly. The trend towards the use of higher strength materials and higher nominal stresses in pressure vessel design, along with the advent of nuclear vessels with their very high reliability requirements, intensified the need for better knowledge of the behavior of reinforced openings in pressure vessels. In recognition of this need, the Subcommittee on Reinforced Openings of the Pressure Vessel Research Committee has sponsored a broad program of both experimental and analytical work directed toward the determination of the behavior of reinforced openings in pressure vessels, considering both the effects of internal pressure and external loads. A summary of this work, as of the time of publication, is given by J.L. Mershon. This report covers one phase of the overall problem of reinforced openings in pressure vessels; specifically, the development of a design procedure for radial nozzles in spherical shells loaded with internal pressure. The design procedure is intended to define acceptable reinforcing details for radial nozzles in spherical vessels, hemispherical heads, torispherical heads provided the opening is in the spherical section sufficiently away from the toroidal section, and ellipsoidal heads in the central section. Reinforcing, if any is required, is assumed to be continuous with the shells, as contrasted to "welded-on" pads. Since limit analysis is used to establish the design procedure, an implied assumption is that the material of the shells and the weld metal is ductile, e.g., is capable of withstanding several percent of local strain in a complex stress field at all temperatures at which the vessel may be loaded.