ASME B31.1a-2008 pdf download.Addenda to ASME B31.1-2007 Power Piping.
displacement stress: a stress developed by the self- constraint of the structure. It must satisfy an imposed strain pattern rather than being in equilibrium with an external load. The basic characteristic of a displacement stress is that it is self-limiting. Local yielding and minor distortions can satisfy the displacement or expansion conditions which cause the stress to occur. Failure from one application of the stress is not to be expected. Fur- ther, the displacement stresses calculated in this Code are “effective” stresses and are generally lower than those predicted by theory or measured in strain-gage tests. 1 peak stress: the highest stress in the region under con- sideration. The basic characteristic of a peak stress is that it causes no significant distortion and is objection- able only as a possible source ofa fatigue crack initiation or a brittle fracture. This Code does not utilize peak stress as a design basis, but rather uses effective stress values for sustained stress and for displacement stress; the peak stress effect is combined with the displacement stress effect in the displacement stress range calculation. sustainedstress: astressdeveloped byanimposedload- ing which is necessary to satisfy the laws of equilibrium between external and internal forces and moments. The basic characteristic of a sustained stress is that it is not self-limiting. If a sustained stress exceeds the yield strength of the material through the entire thickness, the prevention of failure is entirely dependent on the strain- hardening properties of the material. A thermal stress is notclassified as a sustained stress. Further, the sustained stresses calculated in this Code are “effective” stresses and are generally lower than those predicted by theory or measured in strain-gage tests. stress-relieving: see heat treatments.
actual: the shortest distance from the root of a fillet weld to its face. theoretical: the distance from the beginning of the root of the joint perpendicular to the hypotenuse of the larg- est right triangle that can be inscribed within the fillet weld cross section. toe of weld: the junction between the face of the weld and the base metal. tube: refer to pipe and tube. tungsten electrode: a nonfiller metal electrode used in arc welding, consisting of a tungsten wire. undercut: a groove melted into the base metal adjacent to the toe of a weld and not filled with weld metal. visual examination: the observation of whatever portions of components, joints, and other piping elements that are exposed to such observation either before, during, or after manufacture, fabrication, assembly, erection, inspection, or testing. This examination may include verification of the applicable requirements for materials, components, dimensions, joint preparation, alignment, welding or joining, supports, assembly, and erection. weld: a localized coalescence of metal which is produced by heating to suitable temperatures, with or without the application of pressure, and with or without the use of filler metal. The filler metal shall have a melting point approximately the same as the base metal. welder: one who is capable of performing a manual or semiautomatic welding operation. Welder/WeldingOperatorPerformanceQualification (WPQ): demonstration of a welder’s ability to produce welds in amannerdescribedinaWeldingProcedureSpecification that meets prescribed standards. weldingoperator: one who operates machine or automatic welding equipment. Welding Procedure Specification (WPS): a written qualified welding procedure prepared to provide direction for making production welds to Code requirements. The WPS or other documents may be used to provide direc- tion to the welder or welding operator to assure compli- ance with the Code requirements.
101 DESIGN CONDITIONS 101.1 General These design conditions define the pressures, temper- atures and various forces applicable to the design of power piping systems. Power piping systems shall be designed for the most severe condition of coincident pressure, temperature and loading, except as herein stated. The most severe condition shall be that which results in the greatest required pipe wall thickness and the highest flange rating. 101.2 Pressure All pressures referred to in this Code are expressed in pounds per square inch and kilopascals above atmo- spheric pressure, i.e., psig [kPa (gage)], unless otherwise stated. 101.2.2 Internal Design Pressure. The internal design pressure shall be not less than the maximum sustained operating pressure (MSOP) within the piping system including the effects of static head. 101.2.4 External Design Pressure. Piping subject to external pressure shall be designed for the maximum differential pressure anticipated during operating, shut- down, or test conditions. 101.2.5 Pressure Cycling. This Code does not address the contribution to fatigue in fittings and com- ponents caused by pressure cycling. Special consider- ation may be necessary where systems are subjected to a very high number of large pressure cycles. 101.3 Temperature 101.3.1 All temperatures referred to in this Code, unless otherwise stated, are the average metal tempera- tures of the respective materials expressed in degrees Fahrenheit, i.e., °F (Celsius, i.e., °C).