Hydrogeninduced delayed fracture under mode ii loading. This form of cracking is often seen in the low hardness heat affected zone haz region of welds. Sulfide stress cracking oil and gas pipelines wiley online library. Hic test, hydrogen induced cracking test, step wise. The key to success with this steel is the vacuum degassing and calcium treatment for sul. Investigation of stressoriented hydrogeninduced cracking sohic. Corrosionpedia what is hydrogeninduced cracking hic. Stress orientated hydrogen induced cracking sohic is a manifestation of sulfide stress cracking ssc in cmn steels by a mechanism involving the linking of planar cracks normal to. Hisc hydrogen induced stress considerations 1 day course.
If you recall, we mentioned you need all three factors to be present in order to have hic. It involves atomic hydrogen, which is the smallest atom, that diffuses into a metallic structure. Prior to 2003 hydrogen induced cracking hic was not covered by nace mr0175 and it was left to the user to decide on how to address hic concerns. Hydrogen induced cracking hic is a failure mechanism resulting in sudden exposures and cracks due to growing laminations inside the base material and welds. Hydrogen induced cracking hic of austenitic stainless steel ss under mode iii loading can occur during dynamic charging of hydrogen, and the normalized threshold stress was. Sohic is a type of cracking that can easily lead to failure and needs to be mitigated. Important factors on the failure of pipeline steels with. It is characterized by the brittle fracture of a normally ductile alloy under sustained load in the presence of hydrogen.
Hydrogeninduced craking hic, also referred to as hydrogen stress cracking or static fatigue, is a typical form of hydrogen embrittlement. O ur last post factors influencing hydrogen induced cracking went over the factors that contribute to hydrogeninduced cracking. Hic steel is plate which is tested to reduce the effects of hydrogen induced cracking in a wet h 2 s or sour service environment. Hydrogen induced cracking hic damage is a degradation mechanism active in the oil and gas industry. Cracking occurs due to a significant loss in ductility. The steps of a possible mechanism of hydrogeninduced cracking hic can be, first, interstitial diffusion of hydrogen atoms under the steel surface. In this project hydrogen charged samples of alloy 718 and alloy 725 have been exposed under tensile stress to establish critical stress levels for initiation of hisc. Hydrogen induced cracking is a mechanical fracture caused by penetration and diffusion of atomic hydrogen into the internal structure of steel, which changes into molecular. Stress corrosion cracking scc of highstrength steel in aqueous environment and hydrogen induced cracking hic during dynamic charging under mode iii loading were investigated. Unstressed test specimens are exposed to a solution at temperature of.
Prior to 2003, hydrogen induced cracking hic testing was not. Hydrogen induced cracking of pipeline and pressure vessel steels. Sulfide stress cracking oil and gas pipelines wiley. Hydrogeninduced cracking susceptibility in highstrength. The methane molecules create a pressure which leads. Hic, hydrogen induced cracking, hydrogen induced cracking test, ultrasonic, cscan, cscan. Hydrogen induced stress cracking hisc resistance and. Hydrogeninduced cracking susceptibility in highstrength weld metal a formula is proposed to estimate minimum preheat and interpass temperatures which help prevent hydrogeninduced cracking n. Steels with different microstructures were produced by a thermomechanically controlled process tmcp from two different heats.
Stress corrosion cracking in high strength steel under. Hic usually occurs due to the effects of aqueous hydrogen charging of steel in wet h2s refinery process environments. The threshold stress intensities for scc and hic under modes iii and i were measured and compared. It is a complex process that is not completely understood because of the variety and complexity of mechanisms that can lead to embrittlement. Hydrogen induced cracking steel features, applications. Hic is often fairly innocuous but not always, while sohic is a type of cracking that can easily lead to. Susceptibility to sohic for linepipepressure vessel.
Sulfide stress cracking ssc is just one of several forms of hydrogen. Hisc hydrogen induced stress cracking design and material considerations 1 day course if you would like further information on this course, please contact yeechin tang. Preventing hydrogen induced cracking welding answers. Hydrogen induced cracking hic from advanced ndt solutions. Hydrogen induced cracks either follow a linear or stepwise path within the material, hence the term stepwise cracking. Our hic quality plate is ordered to meet more stringent requirements when hydrogen induced cracking tests per the. Region 0 many users did not specify requirements for hic testing or the use of hic resistant. Investigation of stressoriented hydrogeninduced cracking.
Hydrogen induced cracking hic is a common form of wet h2s cracking caused by the blistering of a metal due to a high concentration of hydrogen. Pdf hydrogen induced cracking of api x52 and x60 sour. Hydrogen induced cracking of subsea duplex stainless steel. Hydrogen induced cracking of pipeline and pressure vessel. Hydrogeninduced cracking an overview sciencedirect topics. Hic testing is recommended to evaluate the resistance of pipeline and pressure vessel plate steels to hydrogen induced cracking corrosion caused by hydrogen absorption from aqueous sulfide corrosion. Stressoriented hydrogen induced cracking sohic is a common, insidious form of wet h2s cracking. Processes or conditions involving wet hydrogen sulfide, i. Review of hydrogenassisted cracking models for application to. Effect of nonmetallic inclusions on hydrogen induced cracking.
Naceastm g193 1 includes the following description of hydrogen blistering. Hydrogeninduced cracking hic in steel is a risk problem when steels are charged with hydrogen in service as in various hydrogen sulfide environments like sour oil and gas wells and some power plants. Hydrogen embrittlement susceptibility of 7050 aluminum alloy under various aging states has been investigated by means of cathodic hydrogen permeation, slow strain rate test, hydrogen determinator, xray diffraction, and scanning electron microscope, and effect of hydrogen on atomic binding force of charged alloy has been calculated by free electron theory in this paper. The path of crack growth in hydrogen embrittled steels is a function of the stress intensity factor, k mpavm. Sa516 6070 hic tested plate astm a516516m asme sa516516m grade 606570 hic hydrogen induced cracking tested, sscc sulphide stress corrosion cracking tested, sohic stress oriented hydrogen induced cracking tested fine grained pressure.
Sulfide stress cracking ssc vs hydrogen induced cracking hlc posted in refining, hydrocarbons, oil, and gas. In the case of a crystal lattice becoming saturated. A test project to examine the susceptibility of hydrogen induced stress cracking hisc has been executed. Also high strength structural steels which are welded are exposed to a certain hydrogen pickup which means a risk at fracture and blistering due to hic. We will now go over how to prevent hic from happening. Quantitative experiments indicate a threshold hydrogen concentration for hic below which no cracking will initiate. Pdf hydrogen induced cracking safe materials operating limits. Hydrogen induced crack resistant hic steel plate brown mcfarlane offers the widest range of carbon and stainless steel plate, available exstock. However, under certain stress and material conditions, the cracks can be arranged in a ladderlike array known as stress orientated hydrogen induced cracking sohic. Two types of cracking, namely sulphide stress cracking ssc and hydrogeninduced cracking hic, were evaluated in linepipe steels using nace standard solution to establish the metallurgical parameters that control hic and ssc.
Hic is a unique embrittlement phenomenon as it does not require an externally applied stress or residual stress, though. It is also called hydrogen assisted cracking hac and delayed cracking since it does not occur right after welding, but a few hours or days after the weld has completely cooled down to ambient temperature. The ssc of medium strength steels has been a continuing source of trouble in the oil fields, and from these troubles has evolved in international standards 6. Ssc is one of the many environmental cracking mechanisms resulting in pipeline steels exposed to aqueous sour service environments. In the presence of h 2 s, hydrogen atoms originating from the cathodic reduction reaction driving the anodic dissolution reaction can diffuse into the steel, resulting in cracking mechanisms such as hydrogeninduced cracking hic, sulphide stress cracking ssc and stressoriented hydrogeninduced cracking sohic.
Hic hydrogen induced cracking the project definition. Sulfide stress cracking ssc vs hydrogen induced cracking. Previous studies showed that sulphide stress cracking, hydrogen induced cracking hic and stress corrosion cracking are the main destructive factors in these types of pipes. The formation of subsurface planar cavities, called hydrogen blisters, in a metal resulting from excessive internal hydrogen pressure. S 1700 mpa under mode ii loading were investigated using notched specimens. A hydrogen induced cracking hic is a common form of wet h2s cracking caused by the blistering of a metal due to a high concentration of hydrogen. As we know that both form of cracking are due to the absorption of atomic hydrogen that is produced by. Hydrogen which is produced at cathode due to corrosion reaction, diffuses into the steel and result in cracking in wet hydrogen sulfide environment. The result shows hic and scc under mode ii loading initiated at the back of the notch tip, i. Combining action of atomic hydrogen into hydrogen gas is a cumulative process and builds up of hydrogen gas pressure eventually leads to hydrogen induced cracking hlc. A small number of duplex and superduplex stainless steel components have failed in subsea service due to hydrogen induced stress cracking hisc.
This paper focused on the hic related failure in pipeline steel, since the role of texture and grain boundary character has not been completely recognized. The pressure of the hydrogen gas causes localized internal cracks, known as hydrogen induced cracks. Factors influencing hydrogen induced cracking welding. Failure investigation of hydrogen induced cracking of. More often, fracture occurs at sustained loads below the yield strength of the material. Hydrogen embrittlement he also known as hydrogen assisted cracking hac and hydrogeninduced cracking hic, describes the embrittling of metal after being exposed to hydrogen. The stress field around the notch tip was analyzed by means of finite element method. Stress oriented hydrogen induced cracking sohic sulfide stress cracking ssc banding micro structural alignment e1268 step cooling. Abstract hydrogeninduced cracking hic has been studied phenomenologically. The effect of microstructure on hic is discussed for steels having two different levels of nonmetallic inclusions.
The effect o f accelerated cooling after controlled rolling on the hydrogen induced cracking hic resistance of line pipe steels produced from continuously cast slabs was examined, and the. Effect of microstructure on hydrogeninduced cracking of. The significance of these failures has led to research to define critical loading conditions for hisc, to allow confident design of components in future. Effects of different parameters on initiation and propagation of. The hydrogen atom is the smallest of all atoms and hydrogen attack is similarly insidious and hidden from simple inspection techniques. Stressoriented hydrogeninduced cracking sohic of an amine absorber column made of a hydrogen induced cracking hic resistant steel and operating. Hydrogen combines with carbon within the alloy and forms methane. Steel pipelines and pressurised equipment can operate satisfactorily for up to 8 to 10 years before any cracks are discovered.
Susceptibility to hydrogen induced stress cracking of. Hydrogen induced cracking hic and stressoriented hydrogen induced cracking sohic. Intergranular fracture was identified as the dominant cracking mode. Hydrogeninduced cracking and stress corrosion cracking of. Cracks can develop by both transgranular and intergranular paths. Hydrogeninduced cracking hic is a far too common type of failure. It can occur at relatively low temperatures, largely as a result of atomic hydrogen from wet h2s corrosion reactions which enter the steel and collect at inclusions or.
Stress concentration location based on fe analysis is coincident with experimental observation. Hydrogen embrittlement susceptibility and hydrogeninduced. Detection and characterization of stress corrosion. It is made up of a series of hic hydrogen induced cracking cracks that are stacked perpendicularly in the direction of through wall cracks and driven by high residual or applied stresses. The blistering damage tends to form parallel to the surface and to the direction of hoop stress. Pdf hydrogen induced cracking safe materials operating. Hydrogen induced cracking associated with service loads resulted in catastrophic. It occurs at a rate that depends on the packaging of the iron unit cell, that is, greater diffusibility in the ferrite phase bcc than in. Evidence of undesired loads caused by improper maintenance activities were identified.
298 841 1264 58 75 414 270 1279 253 426 525 698 152 350 32 1027 1105 747 1365 444 1120 1042 1025 710 954 183 696 799 179 664