scholarly journals Measurement of Fatigue and Static Crack Growth Rate of X65 Line Pipe Steel in 3.5% NaCl containing CO2 under Cathodic Polarization

2020 ◽  
Author(s):  
Joseph Tylczak
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Cathodic Polarization ◽  
Pipe Steel ◽  
Line Pipe ◽  
Static Crack ◽  
Line Pipe Steel

Fatigue and Static Crack Growth Rate of Alloy 718 Under Cathodic Polarization

CORROSION ◽  
10.5006/3572 ◽  
2021 ◽  
Author(s):  
Ramgopal Thodla ◽  
Anand Venkatesh
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Cathodic Polarization ◽  
Alloy 718 ◽  
Static Crack ◽  
Rate Behavior

Fatigue crack growth rate was developed on three heats of alloy 718 (UNS N07718) under cathodic polarization, over a wide range of loading conditions. Fatigue crack growth rate increased with decreasing frequency over a range of Kmax and K conditions. In most cases, there was no evidence of a plateau in fatigue crack growth rate at low frequencies. The fatigue crack growth rate over the range of conditions evaluated were influenced by static crack growth rate at Kmax. The principle of superposition of fatigue crack growth and static crack growth was used to rationalize the observed crack growth rate response. Static crack growth rate of alloy 718 measured under constant K conditions, was lower than that measured under rising displacement conditions. A crack tip strain rate based model was used to rationalize the fatigue crack growth rate behavior and the static crack growth rate behavior under constant K. However, the formulation of the model for the rising K was not able to rationalize the crack growth rate under rising displacement conditions.

Fatigue crack growth rates in arctic-grade line pipe steel at high ΔK

1992 ◽  
Vol 26 (11) ◽  
pp. 1693-1694
Author(s):  
C.R. Wake ◽  
J.G. Byrne
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Pipe Steel ◽  
Line Pipe ◽  
Line Pipe Steel ◽  
Crack Growth Rates

Environmentally Assisted Cracking of Subsea Pipelines in Oil & Gas Production Environments—Effect of Static Loading

CORROSION ◽  
10.5006/2896 ◽  
2020 ◽  
Vol 76 (3) ◽  
pp. 312-323
Author(s):  
Ramgopal Thodla ◽  
Feng Gui ◽  
Colum Holtam
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Steady State ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Tip ◽  
Metal Dissolution ◽  
Low Frequencies ◽  
Static Crack

Fatigue crack growth rate of line pipe steels in sour environments typically exhibits a steady-state value at low frequencies. However, in highly inhibited sour environments, there is no evidence of a steady-state fatigue crack growth at low frequencies. This is likely a result of static crack growth rate at Kmax. Stable static crack growth measured under constant stress intensity factor (K) conditions in inhibited sour environments was in the range of 10−7 mm/s to 10−8 mm/s. The crack growth rate in inhibited sour environments is likely associated with crack tip processes associated with metal dissolution/film formation and associated hydrogen evolution. The results obtained were modeled based on a crack tip strain rate based approach, where the rate limiting step was the metal dissolution/FeS formation and the corresponding hydrogen generation reaction.

Fatigue-Crack Growth in an X-65 Line-Pipe Steel at Low Cyclic Frequencies in Aqueous Environments

1975 ◽  
Vol 97 (4) ◽  
pp. 298-304 ◽  
Author(s):  
O. Vosikovsky
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Pipe Steel ◽  
Functional Dependence ◽  
Distinct Pattern ◽  
Cathodic Potential ◽  
Line Pipe ◽  
Line Pipe Steel

The effects of salt and distilled water environments on fatigue-crack growth rates have been evaluated for an X-65 line-pipe steel. Tests were conducted over a frequency range between 10 and 0.01 Hz, under conditions of cathodic potential and free corrosion. A distinct pattern in the functional dependence of growth rates on ΔK and frequency has been found. Maximum environmental enhancement of growth rates was 50 times that of air at a cathodic potential of −1.04V, and 10 times that of air at a free-corrosion potential of −0.68V. In each case it occurred at the lowest frequency and at relatively high values of ΔK. Hydrogen embrittlement and the two-stage cracking process are examined as the main mechanisms of growth acceleration.

Effect of Reeling and pH on the Fatigue Crack Growth Behavior of C-Mn Line Pipe Steels Exposed to Acidizing Environments

2016 ◽  
Author(s):  
Apurva Batra ◽  
Jonathan Bowman ◽  
Weiwei Yu ◽  
Ramgopal Thodla ◽  
Colum Holtam ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Corrosion Rate ◽  
Crack Growth ◽  
Pipe Steel ◽  
Small Scale ◽  
Crack Growth Behavior ◽  
Line Pipe ◽  
Frequency Scan ◽  
Line Pipe Steel

Acidizing treatments are typically performed intermittently during the life of a well. However, more recently there has been a desire to perform an increased number of acidizing treatments in order to improve production. The acidizing treatments typically involve highly corrosive acids, such as hydrofluoric (HF), hydrochloric (HCl) and acetic acid, which are known to cause significant corrosion, but could also lead to environmentally assisted fatigue and fracture. A study was performed to evaluate the effect of cyclic plastic strains associated with reeling installation on the subsequent fatigue crack growth rate (FCGR) behavior of welded C-Mn line pipe steel in acidizing environments. The influence of the pH of the acidizing environment on the FCGR performance was also investigated as part of this study. This paper compares the results of FCGR tests on as-welded (i.e. unstrained) pipe with those from strained and aged welds, as well as quantifying the effect of the pH of the acidizing treatments. Strained and aged welds were obtained by subjecting the as-welded pipe to 4 cycles of full-scale reeling simulation, with each cycle corresponding to 1% strain. Small-scale compact tension (CT) specimens were then extracted from the strained welds and aged at 250°C for one hour to simulate strain aging. FCGR tests were performed in spent acid with corrosion inhibitor on specimens notched in the parent pipe (PP), heat affected zone (HAZ) and weld centerline (WCL) in both the as-welded and strained and aged condition. The majority of the tests were conducted at room temperature (RT) along with a select few tests at elevated temperature (165°F / 74°C). Overall, the results of frequency scan tests indicated that reeling did not have a significant effect on the FCGR behavior of welded C-Mn line pipe steel in spent acid with inhibitor, regardless of which microstructure was sampled. Frequency scan FCGR tests were also performed on strained and aged samples extracted from the intrados side of the strained welds and notched in the PP, HAZ and WCL to investigate the influence of pH on FCGR behavior. Tests were performed in spent acid with inhibitor at RT, with the pH ranging from 3.7 to 6. The observed FCGRs were higher than in air and all microstructures exhibited a frequency dependence (i.e. the FCGR increased with decreasing frequency). At pH = 3.7, the maximum FCGR was approximately 30 times higher than in air and at pH = 5 the FCGR increased to approximately 80 times higher than in air. However, a further increase in pH to 6 produced a decrease in FCGR. The increase in the maximum FCGR is believed to be due to the decrease in corrosion rate with increasing pH leading to reduced crack closure/blunting. However, as the pH increased to around 6, the corrosion rate decreased substantially, which is likely due to a substantial decrease in the concentration of hydrogen being generated, resulting in a lower FCGR. Paris curve FCGR tests were subsequently conducted on strained and aged samples at 0.1Hz.

Fatigue Crack Growth in an X65 Line-Pipe Steel in Sour Crude Oil

CORROSION ◽  
1976 ◽  
Vol 32 (12) ◽  
pp. 472-475 ◽  
Author(s):  
O. VOSIKOVSKY
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crude Oil ◽  
Crack Growth ◽  
Pipe Steel ◽  
Line Pipe ◽  
Sour Crude ◽  
Line Pipe Steel

Hydrogen Embrittlement of Low Alloy Steels Under Cathodic Polarization

CORROSION ◽  
10.5006/3240 ◽  
2020 ◽  
Vol 76 (3) ◽  
pp. 299-311 ◽  
Author(s):  
Ramgopal Thodla ◽  
Narasi Sridhar ◽  
Herman Amaya ◽  
Behrang Fahimi ◽  
Christopher Taylor
Keyword(s):  
Growth Rate ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Water Adsorption ◽  
Cathodic Polarization ◽  
Low Alloy Steels ◽  
Applied Potential ◽  
Alloy Steels ◽  
Rate Limiting

Hydrogen embrittlement of low alloys steels at three different strength levels (745 Mega Pascals [MPa], 904 MPa, and 1,166 MPa) were evaluated under cathodic polarization. Crack growth rate measurements were performed under constant stress intensity (K) conditions, as a function of applied K values as well as applied potential to characterize the behavior of the three different steels. At −1,050 mVSCE saturated calomel electrode (SCE), the threshold stress intensity (Kth) value increased from 44 MPa√m to 60 MPa√m as the yield strength decreased from 1,166 MPa to 745 MPa. The crack growth rate at 66 MPa√m and −1,050 mVSCE decreased from 3 × 10−5 mm/s to 4 × 10−8 mm/s as the yield strength decreased from 1,166 MPa to 745 MPa. For the 1,166 MPa steel at low values of K, the crack growth rate decreased by two orders of magnitude as the potential decreased from −1,000 mVSCE to −950 mVSCE. At higher values of K, the effect of potential on the crack growth rate was not as significant. The 745 MPa steel in general exhibited slow crack growth rate values (2 to 4 × 10−8 mm/s) over the range of K values and applied potentials in which it was evaluated. Water adsorption on fresh metal surfaces in the estimated crack tip chemistry was modeled using density functional theory. The variation in crack growth rate with applied potential at low and intermediate values of K correlated with the fractional coverage of water adsorption on the fresh metal surface. It is proposed that the water reduction reaction and the subsequent generation of hydrogen are the rate limiting steps in the slow subcritical crack growth rate processes for low alloy steels under the conditions evaluated. For the higher values of K, where the crack growth rate showed a weak dependence on applied potential, water reduction, and generation of hydrogen are likely not the rate limiting steps.

Sign in / Sign up

Export Citation Format

Share Document