Pressure vessels (PVs) are classified as fracture critical items in most space systems including the space shuttle, launch vehicles, and spacecraft. Fracture control requirements specified in MIL-STD-1522A are being implemented to the metallic PVs used in most of the space programs. However, requirements in "-1522A" are not applicable to composite overwrapped pressure vessels (COPVs), which are widely used in current space programs. A research, development, test, and evaluation (RDT&E) program is being conducted to generate database needed for establishing fracture control requirements for the COPVs. This paper provides an overview of the fracture control of the metallic PVs and reports important findings obtained from this RDT&E program. The important COPV findings include fatigue and fracture analysis methods used for the metallic liners, nondestructive evaluation techniques, and impact damage effects on the composite overwraps.

Fracture control practices are the engineering procedures and requirements that contribute to the prevention of fracture in metal structures. These practices are identified as the elements of fracture control and each element is defined and described. The systematic application of these practices to the prevention of fracture in a particular structure is accomplished by either the code approach or the performance specification approach to fracture control. In these two approaches, the consideration given to each of the elements of fracture control is discussed and illustrated with examples for specific types of structures. Selected practices that may be of use in Naval systems are discussed. An Appendix contains detailed summaries of the fracture control practices used in each of thirteen classes of metal structures, including ships, offshore structures, bridges, cryogenic tanks, pressure vessels, piping, power generation equipment, and aerospace structures.