ASME NTB-2:2019 pdf free download.Background Information for Addressing Adequacy or Optimization of ASME BPVC Section lll, Division 5 Rules for Metallic Components.

HBB-T- 1430 Limits Using Elastic Analysis

The discussion in Section 17.4.4.7.5 is an overview of the creep-fatigue damage evaluation procedure developed by Severud 1101; it was developed in response to concerns that the original pnwedures were overly conservative and did not account for stress relaxation. The provisions for consideration of inelastic strain concentralion. elastic follow-up. stress relasation. creep shakedown and multiaxial effects are described. The categorization of prcssurc induced secondary stress as primary for thc purposes of creep- damage evaluation in TIIIB-T-l43() is supported by references liii and 1121. The background on elastic follow-up, which led to the overly conservative restrictions in the original procedure. is discussed in Section 17.4.4.3.9.3. Consikrcuion’i for Flu.siic Follow-Up.

HBB-T- 1500 Buckling and Instability

HBB-T-l$l0 Time Independent Buckling and Instability Limits

In Section 17.4.4.3.8 there is a general discussion comparing the approach to evaluation of buckling and instability in Subsection NB. which does not consider creep. to the approach in lIBEl, which does. Also included is a description of bow time-dependent creep buckling differs from time-independent buckling and the difference between load-controlled and strain-controlled buckling.

HBB-T- 1520 Buckling Limits

HBB-T- 1521 lime Independent Buckling

Section 17.4.4.18.1 provides the basis for the time-independent rules in HBH-T-l521.

HBB.T-1522 Time-Dependent Buckling

Section 17.4.4.3.8.2 provides the basis for the time-dependent limits in HI3B-T-l522. When interaction between load-controlled and strain-controlled buckling is present the load-controlled rules of IILIB-T-1522 apply. Section 17.4.4.3.8.4 describes the temperature limit figures in HBB-T-l522 that pcnnit the usc of Subsection NB buckling and instability charts when satisfied.

HBB-T-l710 Special Strain Requirements at Welds

The various factors influencing weld integrity are discussed and the precautions taken to account for them in HBB-T-l7lO are described in Section 17,4.4.3.9.1. Note that this also includes a discussion of the creep rupture strength reduction factors. Additional fabrication and inspection requirements related to weld configuration analyses are in HBB-3353.

IIBB-T-l720 Strain Requirements for Bolting

Section 17.4.4.3.9.2 provides the background for the primary stress Design Limits for bolts in IIBB-3232,

Service Level A and B limits in HBB-3233. Service Level C in HBB-3234. and Service Level D in

HIIB-3235. Also discussed are the rules tr deformation controlled stress and the special provisions in HBB-T- 1721 and HBB-T- 1722 for creep-fatigue damage evaluation.

Scction 5.0 Design Rules for Load-Conirolkd Stresses in Structures other than Bolts is still generally applicable. Section 5.1 on Design Conditions is related to HBB-3222.l. The criteria for determining the time dependent allowable stress values l1r S, based on crcep-rupwrc strength. accumulated strain and onset of third stage creep are identified in Section 5.2. These criteria are in IIHB-322l1b) except that the criteria on stress to produce 1% strain in HBB-322l(b) is based on the average stress not the minimum stress. The discussion in Section 5.3 relates to the allowable stress levels for different loading conditions as shown in FIBB-3222.2. HBB-3223, l-1B13-3224. and HBB-3225. however, the terminology has changed and Normal. LTpset, Emergency, and Faulted have been replaced by Level A. B, C and 1) Service Loadings, respectively, corresponding to a general change in terminology in Section III. The background for loading involving bending is in Section 5.4 and corresponds to the criteria shown in HBB.3222.2. HHB-3223. HBB-3224, and HBB-3225, The usc-fraction discussion in Section 5.5 corresponds to the limits of HBB-3224. which also include HBII-2222 and HBB-2221 The current version of Division 5 also has additional Service Level D criteria based on the strength of weldnwnts as discussed in Section 2.1 of this background document under HBH-3221 which references Section 17.4.4.5.2 of the Companion Guide.

Section 6.0 Design Rules and Limits on Strain for Structural Integrity is still relevant, however. based on additional analytical studies, additional limits have been identified as discussed above in Section 2.1 of this background docLiment under HBB-T-1330 which references Section 17.4.4.3.6.3 of the Companion Guide. The discussion in Section 6.4.1 applies to the rules in 1-IBB-T-l321. 1-IBB.T-1322 and HBB-T-1323. The discussion in Section 6.4.2 applies to the rules in IIBB-T—l330 except for the noted additional limits. Based on additional analyses the geometry restrictions on the applicability of the O’Donncll-Porowsky methodology L141 discussed in Section 64.2 have also been somewhat relaxed in HI3H-T-13311a) to structures in which the peak stress is negligible. The discussion on cycle definition in Section 6.4.3 is still generally applicable.

# ASME NTB-2:2019 pdf free download

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