ASME B31E-2008 pdf download.Standard for the Seismic Design and Retrofit of Above-Ground Piping Systems.
2 MATERIALS 2.1 Applicability This Standard applies to metallic ductile piping sys- tems, listed in the applicable ASME B31 Code section. 2.2 Retrofit The seismic retrofit of existing piping systems shall take into account the condition of the system and its restraints. As part of the seismic retrofit, the piping sys- tem shall be inspected to identify defects in the piping or its supports and current and anticipated degradation that could prevent the system from performing its seis- mic function. 3 DESIGN 3.1 Seismic Loading The seismic loading to be applied may be in the form of horizontal and vertical seismic static coefficients, or horizontal and vertical seismic response spectra. The seismic inputis to be specified by the engineering design in accordance with the applicable standard (such as ASCE 7) or site-specific seismic loading (para. 1.3). The seismic loading shall be specified for each of three orthogonal directions (typically plant east–west, north–south, and vertical). The seismic design should be based on either a three-directional excitation, east–west plus north–south plus vertical, combined by square-root sum of the squares (SRSS), or a two-directional design approach based on the envelope of the SRSS of the east–west plus vertical and north–south plus vertical seismic loading. The seismic loading applied to piping systems inside buildings or structures shall account for the in-structure amplification of the free-field accelerations by the struc- ture. The in-structure amplification may be determined based on applicable standards (such as the in-structure seismic coefficient in ASCE 7) or by a facility-specific dynamic evaluation. The damping for design earthquake response spec- trum evaluation of piping system shall be 5% of critical damping.
3.7.2 The seismic adequacy of seismic restraints shall be determined on the basis of vendor catalogs, and the applicable design method and standard, such as MSS SP-58 or MSS SP-69 for standard support compo- nents, AISC or AISI for steel members, and ACI for concrete anchor bolts. The qualification of seismic restraints shall also address the prevention of buckling. 3.7.3 The seismic adequacy of nonseismic restraints shall also be verified if they are expected to perform a function after the earthquake. For example, spring hangers should not be permitted to pull off the wall if they are necessary to support the pipe weight after the earthquake. 3.7.4 For lateral seismic restraints, a total diametric gap equal to 1 ⁄ 2 in. (12 mm) is acceptable. A gap up to 0.1D or 2 in. (50 mm), whichever is smaller, is permitted, provided the seismic load, calculated on the basis of zero gap, is multiplied by an impact factor of 2. Larger gaps or smaller impact factors may be justified by analy- sis or test. 3.7.5 Short rod hangers [typically less than 12 in. (300 mm) long] may provide a restoring force that tends to limit side-sway of hung pipe, and may be considered as seismic restraints, provided they are designed to sus- tain the seismic loads and movements. 3.8 Equipment and Components The seismic and concurrent loads applied by the pipe at equipment and component nozzles shall be qualified as part of the seismic design or retrofit of the piping system, to a degree commensurate with the required system function, as specified in para. 1.3. For position retention, it is usually sufficient to show that the piping loads on equipment and components will not cause rupture. For leak tightness, the stress shall be maintained withinyield or shownnotto cause fatigue ruptures. For operability, the piping loads shall be kept within operability limits established by detailed analy- sis, testing, or similarity to seismically qualified equip- ment or components.
4 INTERACTIONS Piping systems shall be evaluated for seismic interac- tions. Credible and significant interactions shall be iden- tified and resolved by analysis, testing, or hardware modification. 5 DOCUMENTATION The engineering design shall specify the documenta- tion to be submitted by the designer. 6 MAINTENANCE The piping system shall be maintained in a condition that meets the seismic design requirements for the operating life of the system. In particular, changes to layout, supports, components, or function, as well as material degradation in service shall be evaluated to verify the continued seismic adequacy of the system.