scholarly journals Potential for Stress Corrosion Cracking of A537 Carbon Steel Nuclear Waste Tanks Containing Highly Caustic Solutions

2010 ◽  
Author(s):  
Poh-Sang Lam ◽  
Craig S. Stripling ◽  
Donald L. Fisher ◽  
James B. Elder
Keyword(s):  
Carbon Steel ◽  
Stress Corrosion ◽  
Nuclear Waste ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Welding Residual Stress ◽  
Caustic Solution ◽  
Experimental Program ◽  
General Corrosion ◽  
Waste Tanks

The evaporator recycle streams of nuclear waste tanks may contain waste in a chemistry and temperature regime that exceeds the current corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history found that two of these A537 carbon steel tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved tanks of similar construction. Therefore, it appears that the efficacy of stress relief of welding residual stress is the primary corrosion-limiting mechanism. The objective of this experimental program is to test A537 carbon steel small scale welded U-bend specimens and large welded plates (30.48 × 30.38 × 2.54 cm) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 °C). These conditions simulate worst-case situations in these nuclear waste tanks. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test was completed after 12 weeks of immersion in a similar solution at 125 °C except that the aluminate concentration was reduced to 0.3 M. Visual inspection of the plate revealed that stress corrosion cracking had not initiated from the machined crack tips in the weld or in the heat affected zone. NDE ultrasonic testing also confirmed subsurface cracking did not occur. Based on these results, it can be concluded that the environmental condition of these tests was unable to develop stress corrosion cracking within the test periods for the small welded U-bends and for the large plates, which were welded with an identical procedure as used in the construction of the actual nuclear waste tanks in the 1960s. The absence of evidence of stress corrosion cracking and general corrosion in the laboratory-scaled specimens indicate that this type of nuclear waste tank is not susceptible to highly caustic solutions up to 12 M hydroxide at 125 °C when sufficient nitrite inhibitor is present.

scholarly journals Stress Corrosion Cracking of Carbon Steel Weldments

2005 ◽  
Author(s):  
Poh-Sang Lam ◽  
Changmin Cheng ◽  
Yuh J. Chao ◽  
Robert L. Sindelar ◽  
Tina M. Stefek ◽  
...  
Keyword(s):  
Residual Stress ◽  
Carbon Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Welding Process ◽  
Corrosion Cracking ◽  
Welding Residual Stress ◽  
Temperature History ◽  
Element Analysis ◽  
Nuclear Waste Storage

An experiment was conducted to investigate the role of weld residual stress on stress corrosion cracking in welded carbon steel plates prototypic to those used for nuclear waste storage tanks. Carbon steel specimen plates were butt-joined with Gas Metal Arc Welding technique. Initial cracks (seed cracks) were machined across the weld and in the heat affected zone. These specimen plates were then submerged in a simulated high level radioactive waste chemistry environment. Stress corrosion cracking occurred in the as-welded plate but not in the stress-relieved duplicate. A detailed finite element analysis to simulate exactly the welding process was carried out, and the resulting temperature history was used to calculate the residual stress distribution in the plate for characterizing the observed stress corrosion cracking. It was shown that the cracking can be predicted for the through-thickness cracks perpendicular to the weld by comparing the experimental KISCC to the calculated stress intensity factors due to the welding residual stress. The predicted crack lengths agree reasonably well with the test data. The final crack lengths appear to be dependent on the details of welding and the sequence of machining the seed cracks, consistent with the prediction.

scholarly journals CRACKING CORROSION OF LOW CARBON STEEL IN ENVIRONMENT WITH A HIGH CONCENTRATION OF CO2 AND H2S

2018 ◽  
Vol 55 (5B) ◽  
pp. 210
Author(s):  
Nguyen Thi Le Hien
Keyword(s):  
Carbon Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Low Carbon Steel ◽  
Corrosion Cracking ◽  
Test Method ◽  
General Corrosion ◽  
Low Carbon ◽  
Hydrogen Induced Cracking ◽  
Sulfide Stress

Cracking corrosion of API 5CT Grade L80 Type 1 low carbon steel has been studied in a in brine solutions with H2S 12.3 psia and CO2 9.4 psia. Testing was performed according to the methodology reference from the NACE TM0177, Bent-beam test method in solution B for stress corrosion cracking and sulfide stress corrosion cracking test and NACE TM0284, immersion test method in solution A for Hydrogen induced cracking test.The obtained results showed pitting and general corrosion at both temperatures of 24 oC and 82 oC. In case of stress corrosion cracking (SCC) testing at 82 °C, microscopy of the samples tested for 30 days developed pitting corrosion in the surface and cracking starting in the surface of the samples. The cracks, mostly found in the middle of the samples where the maximum bending occurred. General corrosion was also observed in the samples, with significant decrease in the dimensions of the samples after testing (due to general corrosion). However, in case of sulfide stress corrosion (SSC) and hydrogen induced cracking (HIC) tests at room temperature (24-25 oC), no cracking was observed on the sample. 

NRC/EPRI Residual Stress Validation Program Phase I: Experimental Specimen Modeling and Measurement

2011 ◽  
Author(s):  
J. Broussard ◽  
P. Crooker
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Phase 1 ◽  
Measurement Techniques ◽  
Corrosion Cracking ◽  
Welding Residual Stress ◽  
Hole Drilling ◽  
Pressurized Water

The US Nuclear Regulatory Commission (NRC) and the Electric Power Research Institute (EPRI) are working cooperatively under a memorandum of understanding to validate welding residual stress predictions in pressurized water reactor primary cooling loop components containing dissimilar metal welds. These stresses are of interest as DM welds in pressurized water reactors are susceptible to primary water stress corrosion cracking (PWSCC) and tensile weld residual stresses are one of the primary drivers of this stress corrosion cracking mechanism. The NRC/EPRI weld residual stress (WRS) program currently consists of four phases, with each phase increasing in complexity from lab size specimens to component mock-ups and ex-plant material. This paper describes the Phase 1 program, which comprised an initial period of learning and research for both FEA methods and measurement techniques using simple welded specimens. The Phase 1 specimens include a number of plate and cylinder geometries, each designed to provide a controlled configuration for maximum repeatability of measurements and modeling. A spectrum of surface and through-wall residual stress measurement techniques have been explored using the Phase 1 specimens, including incremental hole drilling, ring-core, and x-ray diffraction for surface stresses and neutron diffraction, deep-hole drilling, and contour method for through-wall stresses. The measured residual stresses are compared to the predicted stress results from a number of researchers employing a variety of modeling techniques. Comparisons between the various measurement techniques and among the modeling results have allowed for greater insight into the impact of various parameters on predicted versus measured residual stress. This paper will also discuss the technical challenges and lessons learned as part of the DM weld materials residual stress measurements.

Stress Corrosion Cracking of Carbon Steel in Ethanol

CORROSION ◽  
2006 ◽  
Vol 62 (8) ◽  
pp. 687-702 ◽  
Author(s):  
N. Sridhar ◽  
K. Price ◽  
J. Buckingham ◽  
J. Dante
Keyword(s):  
Carbon Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking
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