Experimental Evaluation of the Markl Fatigue Methods and ASME Piping Stress Intensification Factors

Abstract

Experimental results of ten girth weld and two unreinforced piping intersections recently tested at Paulin Research Group (PRG) are reported. Results are compared to the original Markl work [1–5] and to current ASME piping design code practices [6]. In addition, approximately 800 experimental tests from the literature [7–32] are compared to the new test results and the existing Mark1 equations. Findings indicate that the original mean girth weld equation provided by Mark1, which serves as the basis of the ASME piping codes, does not match trends expected for as-welded fatigue data. Discrepancies are apparent in the low and high cycle regimes. Finally, the new PRG test data and the existing data from literature are used to develop a new mean girth butt weld curve and to modify the existing ASME piping design codes.

Bridge Safety Dangers - Fatigue Cracks, Brittle Failures and Grit Blasting

“…A 95% confidence level is common for instrumentation calibrations and many applications, but in some cases 99% confidence (one out of 200 permitted failures) is used, e.g., some nuclear power processes. For example, The ASME B31.3 fatigue curves for high cycle fatigue [24,25], are recommended for a 3σ > 99% uncertainty, but a 2σ > 95% uncertainty may be used and is shown in Figure 13. Perhaps a 99% confidence level or higher is appropriate for bridges as well.…”

A post‐processing procedure for predicting high‐ and low‐cycle fatigue life of welded structures based on the master E–N curve

“…The co-authors of the paper performed a series of HCF tests on load/non-load carrying cruciform made from high-strength steel, 59 aluminum alloy, 62 and titanium alloy 58 Besides the fatigue experiments conducted by ourselves, we also collected several HCF and LCF fatigue data of different joint types made of various base metals. These fatigue data include the HCF data of T-and butt joints made of AZ31 magnesium alloy under load-controlled conditions (Figure 11C), 24,67 the low-cycle test of AA5083 deck panel joint (Figure 11D), 60 the LCF test of pipe joint made of SA-106B steel under displacement-control cantilever bending condition (Figure 11E), 61 the HCF test of AL5083/7005 cruciform joints (Figure 11F), 64 the LCF test of longitudinal gusset weld made of various highstrength steel under both load-and displacement-control condition (Figure 11G), 63 LCF test of fillet welds of ship structure under displacement-control condition (Figure 11I), 65 and LCF test of pipe joint made from A53-F carbon steel, under displacement-control fourpoint bending condition (Figure 11K). 63,66 One can refer to the original literature for the details of these experimental tests.…”

“…) corresponding to Δε s,i based on the master E-N curve; and D is fatigue damage fraction and the component is usually considered failure if D ≥ 1.F I G U R E 1 1 Fatigue data of different types of joint analyzed in this study: (A) HCF test of titanium cruciform joints,58 (B) HCF test of steel cruciform joints,59 (C) HCF test of T-and butt joints made from magnesium alloy,23 (D) LCF test of AA5083 deck panel joint,60 (E) LCF test of pipe joint under cantilever bending condition,61 (F) HCF test of AL6082 cruciform joints,62 (G) low-cycle fatigue test of longitudinal gusset weld,63 (H) high-cycle fatigue test of AL5083/7005 cruciform joints,64 (I) low-cycle fatigue test of fillet welds of ship structure,65 (J) LCF test of Q450 steel and T4003 stainless steel,49 and (K) low-cycle fatigue test of pipe joint under four-point bending condition 66. [Colour figure can be viewed at wileyonlinelibrary.com]…”

An analytically formulated structural strain method for fatigue evaluation of welded components incorporating nonlinear hardening effects

“…Three independent sets of fatigue test data of welded components with fatigue lives spanning both high‐cycle and low‐cycle regimes are considered here. The first set represents filleted welded plate‐gusset specimen tests performed by The Welding Institute (TWI), the second set contain girth‐welded pipes sponsored by Welding Research Council (WRC), and the third involves fatigue tests of girth welded pipe to nozzle fitting connections by Paulin Research Group (PRG) . Materials used in these tests involve high‐strength low alloy steels, low carbon steels, and 304 stainless steel.…”

“…Details can be found in their reports. It should also be noted that the gusset‐on‐plate specimen tests by TWI were carried out under load‐controlled conditions, while the tests by PRG and WRC were performed under displacement‐controlled conditions. Nominal strain measurements are available for tests performed by PRG and WRC, while only nominal stress range is available for tests performed by TWI.…”