Probabilistic Life Prediction of Hydrogen Steel Pressure Vessels in Industrial Electric Trucks

2014 ◽  
Author(s):  
Constantinos Minas ◽  
Sejalben Patel

Fuel cell powered industrial electric trucks are widely used in industry where more than 4000 systems are currently installed, achieving more than 20 million operating hours. The electric trucks are equipped with fuel cell power systems instead of an array of lead-acid batteries, which incorporate a permanently mounted pressure vessel containing compressed hydrogen gas and enabling onboard fueling. Fueling can be performed several times a day subjecting the pressure vessel to a large number of pressure cycles. It is critical to design the pressure vessel to withstand the required number of cycles which is in the thousands, over the life of the fuel cell power system estimated at 20000 hours. Steel pressure vessels which are subjected to hydrogen embrittlement are widely used in this application. In order to ensure the safety of the design, a linear elastic fracture mechanics model was developed in order to predict the life of the steel pressure vessel. The developed model was based on the ASME pressure vessel code section KD-10, which uses fatigue crack growth laws based on the relationship between the fatigue crack growth rate (da/dN) and the cyclic intensity factor (ΔK). Two samples were tested under hydrogen cyclic pressure loading. The experimental data was used to obtain estimates for the crack initiation phase. Statistical data was obtained from several hundred systems of the installed base, in order to determine the distributions of the maximum and minimum pressures the vessel is typically subjected to. The probabilistic LEFM model was used in a Monte Carlo simulation where the maximum and minimum pressure assumed a random value based on the equivalent random generator of their associated statistical distribution that is an extreme distribution and a Johnson SB distribution, respectively. The results indicated an increase by a factor of two, in the number of cycles when compared to the cycle prediction based on a constant R-ratio (maximum/minimum fill pressure). The analysis was repeated with normal distribution random generators which resulted in similar results. The results from this analysis ensure the safety of the steel pressure vessel design.

Author(s):  
Kevin A. Nibur ◽  
Chris San Marchi ◽  
Brian P. Somerday

Fatigue crack growth rates and rising displacement fracture thresholds have been measured for a 4130X steel in 45 MPa hydrogen gas. The ratio of minimum to maximum load (R-ratio) and cyclic frequency was varied to assess the effects of these variables on fatigue crack growth rates. Decreasing frequency and increasing R were both found to increase crack growth rate, however, these variables are not independent of each other. Changing frequency from 0.1 Hz to 1 Hz reduced crack growth rates at R = 0.5, but had no effect at R = 0.1. When applied to a design life calculation for a steel pressure vessel consistent with a typical hydrogen trailer tube, the measured fatigue and fracture data predicted a re-inspection interval of nearly 29 years, consistent with the excellent service history of such vessels which have been in use for many years.


Author(s):  
Hiroshi Okano ◽  
Akihide Nagao ◽  
Kazuki Matsubara ◽  
Nobuyuki Ishikawa ◽  
Shusaku Takagi ◽  
...  

Abstract A Type 2 pressure vessel for hydrogen storage, which is made of a combination of a seamless linepipe steel liner and carbon fiber reinforced plastic (CFRP), was developed for hydrogen refueling stations operated at over 70 MPa hydrogen. This newly developed vessel was designed based on various standards such as ASME Sec. VIII Div. 3. However, a leak before break (LBB) methodology has not yet been established for hydrogen. The current study assessed LBB of the Type 2 vessel by a cyclic pressure test in a hydrogen gas atmosphere. The vessel with an artificial flaw was subjected to a cyclic test at pressures between 35 and 93 MPa hydrogen. Hydrogen gas leaked at 7,973 cycles. Eventually, LBB failure was confirmed. This number of cycles to leak was in good agreement with the simulated number, of 9,082 cycles using the crack growth properties in the presence of hydrogen and stress distribution of the thickness direction of the liner calculated by a finite element method. It is suggested that the fatigue crack growth behavior of the pressure vessel can be accurately estimated by using the fatigue crack growth properties in the presence of hydrogen, which correspond to the crack-tip stress-intensity range of an actual pressure vessel.


1994 ◽  
Vol 116 (1) ◽  
pp. 30-35 ◽  
Author(s):  
J. M. Bloom

Current fatigue crack growth procedures in the commercial nuclear industry do not clearly specify how compressive loads are to be handled and, therefore, regulatory agencies usually recommend a conservative approach requiring full consideration of the loads. This paper demonstrates that a more realistic approach to account for compressive loads can be formulated using crack closure concepts. Several empirical plasticity-induced crack closure models were evaluated. An approach in the Section XI ASME Code for tensile loading only has been extended and evaluated for negative R-ratios. However, the paper shows this approach to be overly conservative. The approaches using crack closure models are shown to be more accurate. An analytically based crack closure model, while more complicated, is shown to give a theoretical basis to the empirically derived crack closure models. The paper concludes with a recommendation for modifying the current ASME Code practices consistent with the crack closure models and fatigue crack growth data from negative R-ratio tests.


Author(s):  
Hajime Fukumoto ◽  
Yoru Wada ◽  
Hisao Matsunaga ◽  
Takeru Sano ◽  
Hiroshi Kobayashi

As is well known, low alloy steels are widely used as materials for high pressure vessels because of their high tensile strength and reasonable price, but also show severe hydrogen embrittlement. Therefore, in 2016, the authors introduced a scenario for the safe use of low alloy steels in highly pressurized hydrogen gas as a “Guideline” at ASME PVP 2016 [1]. Following discussions with stakeholders and experts in recent years, we published Technical Document (TD) as an industrial standard prior to regulation, on the safe use of ground storage vessels made of low alloy steels in Hydrogen Refueling Stations (HRSs) based on performance requirements. This article presents an outline of the TD describing the required types of testing as performance requirements for confirming the good hydrogen compatibility of low alloy steels, such as controlling tensile strength in an appropriate range, confirming leak-before-break, determining the life of ground storage vessels by fatigue testing and determining the inspection term by fatigue crack growth analysis using the fatigue crack growth rate in highly pressurized hydrogen.


Author(s):  
Joseph Ronevich ◽  
Chris San Marchi ◽  
Kevin A. Nibur ◽  
Paolo Bortot ◽  
Gianluca Bassanini ◽  
...  

Abstract Following the ASME codes, the design of pipelines and pressure vessels for transportation or storage of high-pressure hydrogen gas requires measurements of fatigue crack growth rates at design pressure. However, performing tests in high pressure hydrogen gas can be very costly as only a few laboratories have the unique capabilities. Recently, Code Case 2938 was accepted in ASME Boiler and Pressure Vessel Code (BPVC) VIII-3 allowing for design curves to be used in lieu of performing fatigue crack growth rate (da/dN vs. ΔK) and fracture threshold (KIH) testing in hydrogen gas. The design curves were based on data generated at 100 MPa H2 on SA-372 and SA-723 grade steels; however, the data used to generate the design curves are limited to measurements of ΔK values greater than 6 MPa m1/2. The design curves can be extrapolated to lower ΔK (< 6 MPa m1/2), but the threshold stress intensity factor (ΔKth) has not been measured in hydrogen gas. In this work, decreasing ΔK tests were performed at select hydrogen pressures to explore threshold (ΔKth) for ferritic-based structural steels (e.g. pipelines and pressure vessels). The results were compared to decreasing ΔK tests in air, showing that the fatigue crack growth rates in hydrogen gas appear to yield similar or even slightly lower da/dN values compared to the curves in air at low ΔK values when tests were performed at stress ratios of 0.5 and 0.7. Correction for crack closure was implemented, which resulted in better agreement with the design curves and provide an upper bound throughout the entire ΔK range, even as the crack growth rates approach ΔKth. This work gives further evidence of the utility of the design curves described in Code Case 2938 of the ASME BPVC VIII-3 for construction of high pressure hydrogen vessels.


Author(s):  
Brian Somerday ◽  
Chris San Marchi ◽  
Kevin Nibur

The objective of this work is to enable the safe design of hydrogen pressure vessels by measuring the fatigue crack growth rates of ASME code-qualified steels in high-pressure hydrogen gas. While a design-life calculation framework has recently been established for high-pressure hydrogen vessels, a material property database does not exist to support the analysis. This study addresses such voids in the database by measuring the fatigue crack growth rates for three heats of ASME SA-372 Grade J steel in 100 MPa hydrogen gas at two different load ratios (R). Results show that fatigue crack growth rates are similar for all three steel heats and are only a mild function of R. Hydrogen accelerates the fatigue crack growth rates of the steels by at least an order of magnitude relative to crack growth rates in inert environments. Despite such dramatic effects of hydrogen on the fatigue crack growth rates, measurement of these properties enables reliable definition of the design life of steel hydrogen containment vessels.


2004 ◽  
Vol 126 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Yanyao Jiang ◽  
Miaolin Feng

Fatigue crack propagation was modeled by using the cyclic plasticity material properties and fatigue constants for crack initiation. The cyclic elastic-plastic stress-strain field near the crack tip was analyzed using the finite element method with the implementation of a robust cyclic plasticity theory. An incremental multiaxial fatigue criterion was employed to determine the fatigue damage. A straightforward method was developed to determine the fatigue crack growth rate. Crack propagation behavior of a material was obtained without any additional assumptions or fitting. Benchmark Mode I fatigue crack growth experiments were conducted using 1070 steel at room temperature. The approach developed was able to quantitatively capture all the important fatigue crack propagation behaviors including the overload and the R-ratio effects on crack propagation and threshold. The models provide a new perspective for the R-ratio effects. The results support the notion that the fatigue crack initiation and propagation behaviors are governed by the same fatigue damage mechanisms. Crack growth can be treated as a process of continuous crack nucleation.


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