NACE MR0175 Exam- Post exam reading on past edition MR0175-2003

Views:
 
Category: Entertainment
     
 

Presentation Description

Post exam reading on earlier version

Comments

Presentation Transcript

slide 1:

NACE MR0175 NACE MR0175 Written Exam Written Exam Post exam reading on past edition MR0175-2003 Historical Reviews of MR0175-2003 2017 Nov 15 th 2017 Nov 15 Reading 10 Hydrogen Sulfide H Charlie Chong/ Fion Zhang

slide 2:

DO NoT Read DO NoT Read This PPT This PPT This is a post exam PASSED di PASSED reading on past edition of MR0175-2003 It may confuse you It may confuse you You need to know the history to be expert Charlie Chong/ Fion Zhang

slide 3:

This is a Post Exam Readimg for those who PASSED only Charlie Chong/ Fion Zhang

slide 4:

Oil Exploration Production p Charlie Chong/ Fion Zhang

slide 5:

Oil Exploration Production p Charlie Chong/ Fion Zhang

slide 6:

Oil Exploration Production p Charlie Chong/ Fion Zhang

slide 7:

Oil Exploration Production p Charlie Chong/ Fion Zhang

slide 8:

Oil Exploration Production p Charlie Chong/ Fion Zhang

slide 9:

Oil Exploration Production p Charlie Chong/ Fion Zhang

slide 10:

Charlie Chong/ Fion Zhang

slide 11:

Charlie Chong/ Fion Zhang

slide 12:

NACE MR0175 Written Exam NACE MR0175 Written Exam Charlie Chong/ Fion Zhang

slide 13:

Introduction The MR0175 CRA written exam is designed to The MR0175 CRA written exam is designed to assess whether a candidate has the requisite knowledge and skills that a minimally qualified MR0175 Certified User-CRA must possess. The exam comprises 50 multiple-choice questions that are based on the MR0175 Standard Parts NACE MR0175 CRA Written Exam that are based on the MR0175 Standard Parts 1 and 3. Test Name TNACE- MR0175 CRA written Written Exam NACE MR0175 CRA-001 Exam Preparation Guide June 2017 Test Name TNACE MR0175 CRA written  Exam T est C ode NA CE-MR0175-CRA-001 T est C ode NA CE-MR0175-CRA-001 Time 4hours Time 4  hour s Number o f Questions 5 0 Format Comput er Based T esting CB T Format Comput er  Based Testing  CB T P a ssing S cor e P ass/F a il Charlie Chong/ Fion Zhang https://www.naceinstitute.org/uploadedFiles/Certification/Specialty_Program/MR0175-CRA-EPG.pdf

slide 14:

Reading 1 Reading 1 SULFIDE STRESS CRACKING – PRACTICAL APPLICATION TO THE OGS S OIL AND GAS INDUSTRY Becky L. Ogden Southwest Petroleum Short Course Southwest Petroleum Short Course Texas Tech University 2005 http://www.halliburton.com/public/multichem/contents/Papers_and_Articles/web/Sulfide-Stress-Cracking-SWPSC-2005.pdf NACE MR0175-2003 NACE MR0175 2003 Charlie Chong/ Fion Zhang

slide 15:

On 20th March 2003 the United States UK and other coalition forces marched into Iraq. Charlie Chong/ Fion Zhang https://www.wessexscene.co.uk/headline/2013/03/20/iraq-10-years-on/

slide 16:

On 20th March 2003 the United States UK and other coalition forces other coalition forces marched into Iraq. Charlie Chong/ Fion Zhang https://www.wessexscene.co.uk/headline/2013/03/20/iraq-10-years-on/

slide 17:

On 20th March 2003 the United States UK and other coalition forces marched into Iraq. Charlie Chong/ Fion Zhang https://www.wessexscene.co.uk/headline/2013/03/20/iraq-10-years-on/

slide 18:

On 20th March 2003 the United States UK and other coalition forces marched into forces marched into Iraq. Charlie Chong/ Fion Zhang https://www.wessexscene.co.uk/headline/2013/03/20/iraq-10-years-on/

slide 19:

ABSTRACT The phenomenon of sulfide stress cracking SSC can result in catastrophic failures of pressurized equipment and piping resulting in extensive damage injuries and possible fatalities Sulfide stress cracking was first identified as a serious problem in possible fatalities. Sulfide stress cracking was first identified as a serious problem in the oil industry in the late 1950’s with the development of deeper sour reservoirs. The high strength materials required for these wells began to fail as a result of brittle fracture that was later identified as SSC Research began on this phenomenon and a fracture that was later identified as SSC. Research began on this phenomenon and a task group was formed which later became associated with the National Association of Corrosion Engineers NACE now known as NACE International. The T-1B itt f NACE bli h d d d ti dd i th t lli committee of NACE published a recommended practice addressing the metallic material requirements for protection against SSC. This recommended practice was later issued in 1975 as the Materials Requirement MR-0175 known today as “Metals fS f S C S C C S Of for Sulfide Stress Cracking and Stress Corrosion Cracking Resistance in Sour Oilfield Environments”. Recently NACE International has issued the International Standard MR0175/ISO 15156 addressing multiple forms of cracking associated with the presence of aqueous hydrogen sulfide. This paper will concentrate on and identify the requirements for SSC to occur and give designers and operators practical options for the prevention of SSC in equipment operating in an aqueous H2S environment. pqppgq While this paper will primarily discuss SSC some insight will be given to address the concerns of other forms of cracking. Charlie Chong/ Fion Zhang

slide 20:

Key Words: hydrogen sulfide cracking sulfide stress cracking SSC partial pressure heat affected zone post weld heat treatment hardness sour environment metallurgy metallurgy Charlie Chong/ Fion Zhang

slide 21:

INTRODUCTION Aqueous hydrogen sulfide H2S in oil and gas production operations can result in many challenges. H2S is a poisonous gas that can result in severe metal loss corrosion as well as catastrophic brittle fractures of pressurized metal loss corrosion as well as catastrophic brittle fractures of pressurized equipment and piping. These brittle fractures to metallic structures can happen quickly with little to no warning or may take years of exposure to pp q y g y y p occur. Several variables can influence a material’s likelihood or its resistance to cracking from exposure to hydrogen sulfide. The physical properties of the material the chemical properties of the material and the environment to material the chemical properties of the material and the environment to which it is exposed all play an important role in determining whether a material is susceptible to SSC. Sulfide stress cracking or SSC is defined by NACE as the “Cracking of a metal under the combined action of tensile stress and corrosion in the metal under the combined action of tensile stress and corrosion in the presence of water and H2S a form of hydrogen stress cracking.” Through the review of this definition several factors must be present for SSC to occur. These factors are 1 a susceptible material 2 tensile stress 3 hydrogen sulfide and 4 water. If any one of these factors is missing sulfide stress cracking will not occur. Charlie Chong/ Fion Zhang cracking will not occur.

slide 22:

Through the review of this definition several factors must be present for SSC tThft to occur. These factors are: 1. a susceptible material 2 tensile stress 2. tensile stress 3. hydrogen sulfide and 4. water. If any one of these factors is missing sulfide stress cracking will not occur. susceptible material tensile stress hydrogen sulfide SSC Charlie Chong/ Fion Zhang

slide 23:

SCC Through the review of this definition several factors must be present for SSC to occur. These factors are 1 a susceptible material 2 tensile stress 3 hydrogen sulfide and 4 water If any one of these factors is missing sulfide hydrogen sulfide and 4 water. If any one of these factors is missing sulfide stress cracking will not occur. susceptible material p tensile stress hydrogen sulfide SSC Aqueous Environment Charlie Chong/ Fion Zhang

slide 24:

Hydrogen Stress Cracking HSC yg g susceptible material SSC tensile stress Applied or residual Nascent Hydrogen Welding/ H 2 S etc. Charlie Chong/ Fion Zhang

slide 25:

Stress Corrosion Cracking g susceptible material SCC tensile stress Applied or residual Environment Cl - /H 2 S etc. Charlie Chong/ Fion Zhang

slide 26:

Stress Corrosion Cracking g Charlie Chong/ Fion Zhang

slide 27:

Cl - Stress Corrosion Cracking g susceptible material Cl - SCC tensile stress Applied or residual Cl - Environment Charlie Chong/ Fion Zhang

slide 28:

■ ωσμ· Ωπ∆ º ≠δ≤ ηθφФρ| β≠Ɛ ∠ ʋ λ α ρτ√ ≠≥ѵФε ≠≥ѵФ : Cl - Stress Corrosion Cracking – Originated from surface protective film rupture protective film rupture Charlie Chong/ Fion Zhang

slide 29:

Cl - Stress Corrosion Cracking – Originated from surface protective film rupture protective film rupture Charlie Chong/ Fion Zhang

slide 30:

Cl - Stress Corrosion Cracking – Originated from surface protective film rupture protective film rupture Charlie Chong/ Fion Zhang

slide 31:

Cl - Stress Corrosion Cracking- Duplex Steel – Originated from surface protective film rupture Originated from surface protective film rupture Charlie Chong/ Fion Zhang

slide 32:

Cl - Stress Corrosion Cracking Duplex Steel – Originated from surface protective film rupture Originated from surface protective film rupture Charlie Chong/ Fion Zhang

slide 33:

Cl - Stress Corrosion Cracking – Originated from surface protective film rupture protective film rupture Charlie Chong/ Fion Zhang

slide 34:

MATERIAL PROPERTIES Steel is essentially a combination of iron and carbon with minor amounts of alloying elements added that enable that iron/carbon combination to perform the mechanical and chemical requirements of a particular grade of steel or the mechanical and chemical requirements of a particular grade of steel or alloy. The primary elements added include manganese silicon phosphorus chromium nickel and molybdenum. Each of these elements is added in y varying concentrations so as to enhance the steel’s properties. However with regards to sulfide stress cracking or other forms of cracking these alloying elements must be reviewed and in some cases minimized elements must be reviewed and in some cases minimized. Charlie Chong/ Fion Zhang

slide 35:

Materials have to be strong enough to perform under the conditions we require for our production conditions and designs. However generally with strength comes brittleness. Steels must be strong to perform yet ductile enough to prevent brittle fractures. A delicate balance must be obtained. As a result of laboratory testing and field experience NACE MR-0175:2003 details the parameters of acceptable chemical composition physical properties manufacturing processes and fabrication processes that will yield a material acceptable for processes and fabrication processes that will yield a material acceptable for use in a NACE defined sour environment. These parameters as they pertain to carbon steel materials will be detailed in a later section of this paper. Keywords:  strong to perform gp  ductile enough to prevent brittle fractures  NACE MR-0175:2003 details the parameters of acceptable: of laboratory testing and field experience prescribed/documented • of laboratory testing and field experience prescribed/documented • chemical composition physical properties manufacturing processes and fabrication processes. Charlie Chong/ Fion Zhang p

slide 36:

FACTORS AFFECTING SULFIDE STRESS CRACKING Generally speaking an environment that produces hydrogen sulfide is considered “sour”. However for the environment to be defined as NACE sour it must exhibit characteristics that are favorable for the initiation of sulfide it must exhibit characteristics that are favorable for the initiation of sulfide stress cracking. NACE MR0175:2003 defines the conditions in which SSC can occur. For the purpose of this discussion a “sour” environment shall be one in which the conditions are conducive to cracking by hydrogen sulfide conditions are conducive to cracking by hydrogen sulfide. It is important to understand that the environments which can result in the SSC of materials are very specific in their compositions. SSC does not occur under all operating conditions. Several factors affect whether or not SSC will occur to a particular metallic structure. Charlie Chong/ Fion Zhang

slide 37:

These factors include The Materials Characteristics 1 the alloy composition 2 the material’s yield strength and 3 hardness properties 4 heat treatment 4 heat treatment 5 microstructure Th S i C diti The Service Conditions a fluid pH b partial pressure of H2S pp c total applied tensile stress and d cold work e temperature and e temperature and f time. How each of these impacts the SSC potential is discussed below. Charlie Chong/ Fion Zhang

slide 38:

Alloy Composition The composition of a metallic material determines its susceptibility or resistance to various forms of cracking when exposed to particular environments Generally speaking iron based materials or ferrous metals environments. Generally speaking iron based materials or ferrous metals are more susceptible to SSC than nickel based alloys or non-ferrous materials. Additionally various levels of resistance/susceptibility to SSC can be found within a given family of alloys due to chemical compositional differences. Therefore each material should be reviewed prior to use to ensure it is acceptable for the intended use ensure it is acceptable for the intended use. Yield Strength and Hardness Properties Ilthhihthtthf llthhdth tildth In general the higher the strength of an alloy the harder the material and the more susceptible it is to sulfide stress cracking. Although yield strength is a true material property hardness is not. pp y Charlie Chong/ Fion Zhang

slide 39:

However there is a correlation between the two measurements. Generally the higher the yield strength the higher the hardness value. In most commercial grades of ferrous alloys the maximum strength level In most commercial grades of ferrous alloys the maximum strength level suitable for sour service use is:  90000 psi yield strength. This roughly correlates to 22 Rockwell C HRC or 235 Brinell BHN hardness. This is often quoted for ferrous steels used in a NACE sour service. However through controlling steel chemistry and using special mill processing this li it b i d T ti d lifi ti f t i l b upper limit can be increased. Testing and qualification of materials can be performed to determine its suitability for use in sour systems. Charlie Chong/ Fion Zhang

slide 40:

Although hardness is not a true material property it is the preferred method of testing because it is simple and easy to perform relatively non-destructive and in most cases portable. Hardness values can be utilized by manufacturers and procurement agents as a quality control method during the manufacturers and procurement agents as a quality control method during the 1 fabrication process or 2 by the field personnel as a field inspection technique. Additional discussions on hardness determinations are discussed in the next section section. Charlie Chong/ Fion Zhang

slide 41:

Keywords:  In most commercial grades of ferrous alloys the maximum strength level suitable for sour service use is 90000 psi yield strength. This roughly correlates to 22 Rockwell C HRC or 235 Brinell BHN hardness correlates to 22 Rockwell C HRC or 235 Brinell BHN hardness.  However through controlling steel chemistry and using special mill processing this upper limit can be increased. Testing and qualification of materials can be performed to determine its suitability for use in sour systems systems. Charlie Chong/ Fion Zhang

slide 42:

Heat Treatment The type of heat treatment applied to a particular alloy can affect the material’s microstructure and ultimately its susceptibility to sulfide stress cracking A microstructure comprised of tempered martensite with fine grains cracking. A microstructure comprised of tempered martensite with fine grains will result in materials of superior resistance to SSC. Carbon and low alloy steels are acceptable in the as-milled condition as long Carbon and low alloy steels are acceptable in the as milled condition as long as they contain less than 1 nickel meet the hardness requirements and are in one of the following heat-treatment conditions:  ht ll d b t l l  hot-rolled carbon steels only  annealed  normalized  normalized and tempered  normalized austenitized quenched and tempered or  austenitized quenched and tempered  austenitized quenched and tempered. It should be noted that field fabrication cold working and welding of “approved” materials can alter the microstructure making the material approved materials can alter the microstructure making the material susceptible to SSC. It may be necessary to thermally stress relieve the materials following these processes to “reinstate” their resistance to SSC. Charlie Chong/ Fion Zhang

slide 43:

Materials Heat Treatment 1. Anneal Usually refers heating a cold-worked metal to soften it by allowing it to recrystallize. yg yg y 2. Austenitic or Normalize Heating a ferrous alloy above its upper critical temperature – to the austenite phase on the phase diagram. 3. Cold-work Plastic deformation of metal usually at room temperature to increase hardness. 4. Hot-working A tl f i ti th t i f d b t l’ t lli ti t t Any metal-forming operation that is performed above a metal’s recrystallization temperature. 5. Precipitation/age hardened Hardening and strengthening of a metal alloy by extremely small and uniformly dispersed particles that precipitate from a supersaturated solid solution particles that precipitate from a supersaturated solid solution. 6. Solid solution Single crystalline phase containing two or more elements 7. Solution-annealing 7. Solution annealing Heating a material to and holding it at temperature for long enough to dissolve any carbides followed by rapid cooling to ensure carbides cannot re-precipitate and reduce corrosion resistance. 8. Stress relieved Heating a metal to a suitable temperature and holding for long enough to reduce residual stresses and then cooling slowly enough to minimize the development of new residual stresses 9. Tempered Heating steel to a temperature below the lower critical temperature to decrease hardness dith fh d d t l Charlie Chong/ Fion Zhang and increase toughness of hardened steel

slide 44:

Hotwork anneal quanched and tempered Charlie Chong/ Fion Zhang

slide 45:

Quanched and tempered martensite Charlie Chong/ Fion Zhang

slide 46:

Quanched and tempered Charlie Chong/ Fion Zhang

slide 47:

Quanched and tempered Charlie Chong/ Fion Zhang

slide 48:

Critical inter-critical and sub-critical anneal Stress relif Charlie Chong/ Fion Zhang

slide 49:

Stress Relief Charlie Chong/ Fion Zhang

slide 50:

Cryogenic soaked Dual tempered Charlie Chong/ Fion Zhang https://www.industrialheating.com/articles/93199-temperature-control-during-cryogenic-processing

slide 51:

Microstructure Although susceptibility to SSC increases with increasing hardness some microstructures are more susceptible to cracking than others at the same hardness levels As stated above the tempered martensite is more resistant hardness levels. As stated above the tempered martensite is more resistant to SSC than the tempered bainite or mixed structures of the same hardness. Additionally the degree of segregation and the type size shape and distribution of inclusions are other microstructural variables that can influence the resistance to sulfide stress cracking. Fluid pH The higher the fluid pH the more resistant materials are to SSC. This t d bl d illi ti t tili hi h t th t i l i tendency enables drilling operations to utilize high strength materials in zones known to produce H 2 S. Although pH control is acceptable and manageable in drilling operations it is not readily utilized in production scenarios. Maintaining gp y p g a constant pH in production would prove troublesome and impractical. Therefore hardness limitations and alloy selections are the preferred method for controlling SSC for controlling SSC. Charlie Chong/ Fion Zhang

slide 52:

Partial Pressure of H2S P H2S As the partial pressure of H2S increases the susceptibility of a material to SSC increases. The partial pressure of H2S is defined as the portion of the total pressure associated with the specific component of interest in this case total pressure associated with the specific component of interest in this case H2S. The partial pressure is calculated by multiplying the total system pressure by the mole fraction of H2S in the gas phase. If the calculated partial pressure of H2S is above 0.05 psia in a gas system SSC is possible. Figures 1 and 2 show the relationship to H2S system pressure and partial pressure for gas and multiphase systems as illustrated by NACE pressure for gas and multiphase systems as illustrated by NACE MR0175:2003 edition. It should be noted that these limits are a “practical” limit due to other factors affecting SSC materials have failed at partial bl 005 i Th f h ldb t k t i ll pressures below 0.05 psia. Therefore care should be taken to review all factors involved in the material selection. Charlie Chong/ Fion Zhang

slide 53:

Total Applied Tensile Stress and Cold Work Different alloys possess different threshold levels at which SSC will occur. Understanding this threshold level will enable the designer to ensure that the stresses applied to a material will not result in cracking It needs to be stresses applied to a material will not result in cracking. It needs to be understood that the total stresses working on a material are the combination of both the applied stress i.e. pressure and the residual stress fabrication/manufacturing stresses. The higher the applied stress on a material the more susceptible to SSC it becomes. Cold work or cold formed materials may be susceptible to SSC at hardness levels below HRC 22 BHN 235. Cold working will 1 alter the microstructure d 2 i th id l f t il t and 2 increase the residual surface tensile stresses. For this reason heat treatment is recommended for cold worked or cold formed low alloy steels before they are used in a sour environment. An annealing or normalizing heat treatment will return the material to its original SSC resistance following cold working SSC resistance following cold working. Charlie Chong/ Fion Zhang

slide 54:

Temperature The potential for SSC decreases as temperatures increase. Therefore additional high strength tubing and casing materials can be utilized above threshold temperatures However if a well is to be completed or operated in threshold temperatures. However if a well is to be completed or operated in a sour zone with a temperature above a threshold temperature for a particular material the engineer must confirm that the environment in contact with the material does not drop below that critical temperature. Below this temperature these high strength materials are susceptible to SSC and cannot be utilized. Table A3 an excerpt from the NACE MR0175:2003 standard illustrates the Table A.3 an excerpt from the NACE MR0175:2003 standard illustrates the temperature dependence of tubing and casing materials in oil and gas wells. Charlie Chong/ Fion Zhang

slide 55:

Table A.3 — Environmental conditions for which grades of casing and tubing are acceptable Charlie Chong/ Fion Zhang

slide 56:

...the engineer must confirm that the environment in contact with the material does not drop below that contact with the material does not drop below that critical temperature. Charlie Chong/ Fion Zhang

slide 57:

...the engineer must confirm that the environment in contact with the material does not drop below that critical temperature that critical temperature. Charlie Chong/ Fion Zhang

slide 58:

...the engineer must confirm that the environment in contact with the material does not drop below that critical temperature. Charlie Chong/ Fion Zhang

slide 59:

Time The general rule of thumb is “the longer the time of exposure at a constant stress level the greater the danger of SSC for susceptible alloys”. Under laboratory controlled conditions it is possible to determine the time to failure laboratory controlled conditions it is possible to determine the time to failure of a given alloy under a particular set of conditions. However in actual field conditions projecting a time to failure is extremely difficult. The time it takes for a material to fail due to SSC is dependent on the aggressiveness of the environment and the degree of susceptibility of the material. SSC can happen quickly or may take years to develop Therefore it is critical that a review of quickly or may take years to develop. Therefore it is critical that a review of the materials and environment be conducted prior to specifying the completion equipment. SSC resistant materials should be utilized. Charlie Chong/ Fion Zhang

slide 60:

Time Charlie Chong/ Fion Zhang

slide 61:

HARDNESS TESTING OF MATERIALS While hardness testing is a simple procedure it must be performed correctly and must represent the material in the as-received or as-fabricated condition. Hardness by definition is the resistance of a metal to plastic deformation Hardness by definition is the resistance of a metal to plastic deformation usually by an indention. Hardness testers utilize an indenter which is forced into the metal surface by a known loading. The relationship to the area or yg p depth of the indentions to the load applied is known as the hardness of the material. Hardness can be measured on multiple “scales”. NACE MR0175 utilizes the:  Rockwell C scale HRC or  the Brinell scale BHN. If hardness values are specified for the parent metal and any heat affected If hardness values are specified for the parent metal and any heat affected zones left in the as-welded or as-milled condition there shall be a sufficient number of hardness tests performed to ensure the readings are below the specified value as noted within NACE MR0175/ISO 15156:2003 for that particular material. Controlling hardness is an acceptable method for preventing SSC. Charlie Chong/ Fion Zhang preventing SSC.

slide 62:

MR0175/ISO 15156:2003 does not specify the number or locations of hardness tests on the parent material. However if hardness control is to be utilized for approving a welding However if hardness control is to be utilized for approving a welding procedure for use in sour services specific locations and numbers of tests must be performed. These are noted within the International NACE MR0175/ISO 15156:2003 standard for Vickers and Rockwell Hardness measurements for fillet welds butt welds and repair/partial penetration welds. These illustrations must be followed for weld procedure qualifications These illustrations must be followed for weld procedure qualifications. Charlie Chong/ Fion Zhang

slide 63:

WELDING AND ITS IMPACT ON SSC Welding is a “necessary evil” in sour systems in the oil and gas industry however steps can be taken to minimize its negative impacts. When steel is welded the parent material and consumables are variables that must be welded the parent material and consumables are variables that must be reviewed and controlled. But these are not the only variables that need to be considered when welding in sour service. g The effects of rapid cooling in the heat affected zone HAZ of a weld can result in areas of localized hardness The HAZ is that area around the actual result in areas of localized hardness. The HAZ is that area around the actual weldment that has been exposed to high temperatures but not high enough to actually liquefy the material. However as a result of this heat input phase transformations do occur resulting in a microstructure has been “partially melted” recrystalized and altered due to the heat of welding. This altered HAZ is now more susceptible to SSC due to its increased hardness A parent HAZ is now more susceptible to SSC due to its increased hardness. A parent material that was suitable and acceptable in regard to SSC in its as-received as-milled condition may be susceptible to SSC following fabrication that involves welding. Therefore fabrication processes involving welding must be reviewed for their potential impact on the SSC potential of the parent material. Charlie Chong/ Fion Zhang

slide 64:

Weld procedures can be written and qualified as being in compliance with NACE with regard to both SSC and other forms of cracking associated with the presence of aqueous hydrogen sulfide. The qualification requirements for hardness measurements traverse across the weld are detailed in the NACE hardness measurements traverse across the weld are detailed in the NACE MR0175/ISO 15156:2003 Standard as stated in the previous section on hardness measurements. However in lieu of qualifying a weld procedure to NACE one also has the option to post weld heat treat PWHT following the completion of the welding option to post weld heat treat PWHT following the completion of the welding. The use of a PWHT technique tempers the welded material. This reduces the residual internal stresses created when the weld metal solidified and tempers t it th t b t i t fi ti f l i t l t i any martensite that may be present into a configuration of lower internal strain. The process of PWHT will be specific for each type and thickness of material and the procedures are described within ASME Boiler and Pressure p Vessel Code Section 8 Division 1. Charlie Chong/ Fion Zhang

slide 65:

When specifying line pipe for sour service it has been this author’s experience to prefer the seamless line pipe over Electric Resistance Weld ERW pipe. When ERW pipe was utilized the specification always called for full body normalizing following manufacturing verses only seam annealing full body normalizing following manufacturing verses only seam annealing following manufacturing. In my experience this proved to provide better resistance to SSC when exposed to the severe H2S environments in the Permian Basin area of West Texas and Southeastern New Mexico. Charlie Chong/ Fion Zhang

slide 66:

Heat Affected Zone Charlie Chong/ Fion Zhang

slide 67:

Heat Affected Zone Charlie Chong/ Fion Zhang

slide 68:

Heat Affected Zone Charlie Chong/ Fion Zhang

slide 69:

Heat Affected Zone Charlie Chong/ Fion Zhang http://www.kobelco-welding.jp/education-center/medium/medium02.html

slide 70:

Heat Affected Zone http://pubs.sciepub.com/jmpc/1/4/1/ Charlie Chong/ Fion Zhang

slide 71:

USE OF PLATINGS AND COATINGS While platings and coatings are an acceptable barrier for generalized corrosion they are not acceptable for use in the prevention of SSC as per NACE MR0175 2003 NACE MR0175-2003. Charlie Chong/ Fion Zhang

slide 72:

DETERMINING A SOUR ENVIRONMENT Hydrogen sulfide is one of the most serious corrosion agents encountered in the oil and gas industry. In addition to its ability to crack metals it can also result in pitting corrosion with subsequent failures The release of H2S as a result in pitting corrosion with subsequent failures. The release of H2S as a result of corrosion or cracking can endanger the lives of people working around or in near proximity to the release point. H2S can be fatal at py p concentrations as low as 500 ppm. Therefore designing equipment resistant to H2S cracking is critical. Additionally prevention of corrosion by H2S is also highly recommended Inhibition of corrosion can be obtained through material highly recommended. Inhibition of corrosion can be obtained through material selection internal coatings or the application of corrosion inhibitor. However to prevent cracking the NACE standard must be strictly adhered to and followed. Charlie Chong/ Fion Zhang

slide 73:

It is the responsibility of the owner/user to determine whether a given environment falls within the parameters of a sour environment thus requiring SSC resistant materials. Information concerning the environment’s operating pressure H2S content water content pH and temperature all play a role in pressure H2S content water content pH and temperature all play a role in making this determination. Designing for SSC resistance is not only a prudent and good engineering practice but it is a requirement of many regulatory agencies. Specifically the Texas Railroad Commission Rule 36 the BLM On- Shore Order 6 and the New Mexico Statewide Rule 118 all specify that SSC resistant materials must be utilized in an H2S environment Therefore SSC resistant materials must be utilized in an H2S environment. Therefore this is both critical for safety and regulatory compliance Charlie Chong/ Fion Zhang

slide 74:

Note: Currently the regulations still specify NACE MR0175 latest edition as the standard for compliance. It is unknown as of the writing of this paper as to whether the agencies will adopt the new International MR0175/ISO 15156 Standard However producers should be aware of the changes published in Standard. However producers should be aware of the changes published in the new standard and be prepared to make appropriate modifications to fabrication and engineering specifications. Charlie Chong/ Fion Zhang

slide 75:

Referring again to Figures 1 and 2 will enable the user/owner to evaluate his/her system based on H2S content and pressure assuming the presence of free water. It should be noted that hydrogen sulfide can be present naturally in produced fluids or can be introduced as a result of contamination by incompatible waters or sulfate reducing bacteria. Frequent surveys of non-sour or “sweet” fluids should be conducted to determine if hydrogen sulfide generation is occurring over the life of a well or producing field All safety precautions occurring over the life of a well or producing field. All safety precautions should be exercised when determining the concentration of H2S in production fluids. Because of the dangers associated with low concentrations of H2S it iddtl H2Si tdlftht is recommended to always assume H2S is present regardless of the past history of a field lease or individual well. Charlie Chong/ Fion Zhang

slide 76:

OTHER FORMS OF HYDROGEN DAMAGE In addition to SSC there are other forms of hydrogen damage and cracking that can occur in aqueous hydrogen sulfide environments. Because the potential for catastrophic failures associated with these forms of cracking also potential for catastrophic failures associated with these forms of cracking also exists NACE has recently published a joint international standard NACE MR0175/ISO 15156:2003. This standard addresses the concerns for all types yp of cracking associated with sour production and makes recommendations for materials and operating conditions to prevent such failures. Charlie Chong/ Fion Zhang

slide 77:

Hydrogen Induced Cracking HIC Hydrogen Induced Cracking HIC is defined as a “hydrogen attack induced by decarburization”. This type of attack occurs at elevated temperatures HTHA and is caused by atomic hydrogen permeating through the steel and HTHA and is caused by atomic hydrogen permeating through the steel and reacting to form other gases. Hydrogen reacts with the carbon in the steel to form methane gas which cannot diffuse out of the steel’s matrix. Accumulation of this methane at grain boundaries and other steel discontinuities results in localized high stresses from which cracks can occur. HIC attack generally occurs at temperatures greater than 500 ° F and is dependant on the occurs at temperatures greater than 500 F and is dependant on the hydrogen partial pressure. Consult the API Publication 941 Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum R fi i d P t h i l Pl t f dditi l i f ti thi Refineries and Petrochemical Plants for additional information on this phenomenon. Charlie Chong/ Fion Zhang

slide 78:

ISO 15156-1:2009E 3.12 hydrogen-induced cracking HIC HIC planar cracking that occurs in carbon and low alloy steels when atomic hydrogen diffuses into the steel and then combines to form molecular hydrogen at trap sites NOTE Cracking results from the pressurization of trap sites by hydrogen No NOTE Cracking results from the pressurization of trap sites by hydrogen. No externally applied stress is required for the formation of hydrogen-induced cracks. Trap sites capable of causing HIC are commonly found in steels with hi h i itllthth hihdit f high impurity levels that have a high density of: 1 planar inclusions and/or p 2 regions of anomalous microstructure e.g. banding produced by segregation of impurity and alloying elements in the steel. This form of hydrogen-induced cracking is not related to welding. Charlie Chong/ Fion Zhang

slide 79:

HTHA- High Temperature Hydrogen Attack Charlie Chong/ Fion Zhang http://www.csb.gov/csb-investigation-finds-2010-tesoro-refinery-fatal-explosion-resulted-from-high- temperature-hydrogen-attack-damage-to-heat-exchanger/

slide 80:

HTHA- High Temperature Hydrogen Attack Charlie Chong/ Fion Zhang

slide 81:

HTHA- High Temperature Hydrogen Attack Charlie Chong/ Fion Zhang

slide 82:

HTHA- High Temperature Hydrogen Attack Charlie Chong/ Fion Zhang

slide 83:

HTHA- High Temperature Hydrogen Attack Charlie Chong/ Fion Zhang

slide 84:

Step Wise Cracking SWC Step Wise Cracking SWC is defined as “hydrogen cracks which lie parallel to each other and are connected by cracks between them”. This type of cracking can be either discrete cracks or an array of cracks The cracks that cracking can be either discrete cracks or an array of cracks. The cracks that connect the “main cracks” and lead to SWC are caused by the shear stresses between the main cracks. This type of cracking can lead to catastrophic failures due to the potential for the cracks to propagate through the thickness of the material resulting in a considerable loss of strength and ultimate failure. Charlie Chong/ Fion Zhang

slide 85:

ISO 15156-1:2009E 3.20 stepwise cracking SWC SWC cracking that connects hydrogen-induced cracks on adjacent planes in a steel NOTE This term describes the crack appearance. The linking of hydrogen-induced cracks to produce stepwise cracking is dependent on the local strain between cracks to produce stepwise cracking is dependent on the local strain between the cracks and the embrittlement of the surrounding steel by dissolved hydrogen. HIC/SWC is usually associated with low-strength plate steels used in the production of pipes and vessels. ppp Charlie Chong/ Fion Zhang

slide 86:

Stress Oriented Hydrogen Induced Cracking SOHIC Stress Oriented Hydrogen Induced Cracking SOHIC is defined as “hydrogen induced cracking propagated by high internal stresses typically hoop stress” This type of high internal stresses typically hoop stress . This type of cracking is similar to HIC and SSC but the cracking is transgranular or across the grains in the through thickness direction. These cracks initiate and propagate in the direction normal to the applied stress and are typically observed in the HAZ of relatively high hardness typically observed in the HAZ of relatively high hardness microstructures. The application of a high external stress i.e. pressure typically contributes to the failure. Charlie Chong/ Fion Zhang

slide 87:

ISO 15156-1:2009E 3.22 stress-oriented hydrogen-induced cracking SOHIC SOHIC staggered small cracks formed approximately perpendicular to the principal stress residual or applied resulting in a “ladder-like” crack array linking sometimes small pre-existing HIC cracks NOTE The mode of cracking can be categorized as SSC caused by a NOTE The mode of cracking can be categorized as SSC caused by a combination of external stress and the local strain around hydrogen-induced cracks. SOHIC is related to SSC and HIC/SWC. It has been observed in t til flitdi ll lddi dithh t ff t d parent material of longitudinally welded pipe and in the heat-affected zone HAZ of welds in pressure vessels. SOHIC is a relatively uncommon phenomenon usually associated with low-strength ferritic pipe and pressure- py gpp p vessel steels. Charlie Chong/ Fion Zhang

slide 88:

Hydrogen Blistering Hydrogen Blistering is defined as the “subsurface cracking from absorption and concentration of hydrogen”. Blistering occurs when hydrogen enters the steel and combines into molecular hydrogen at defects present in the steel steel and combines into molecular hydrogen at defects present in the steel plate typically non-metallic inclusions such as sulfides. Hydrogen blistering generally occurs in low pressure equipment such as tanks and pipeline equipment that are exposed to a corrosive environment that contains hydrogen sulfide. Because of the nature of the manufacturing process of rolled plates Because of the nature of the manufacturing process of rolled plates inclusions present in the steels become elongated with the larger inclusions present and aligned along the centerline of the plate. It is at these larger i l i th t h d bli t i t d t Th hi h i t l inclusions that hydrogen blistering tends to occur. The high internal pressures present with the formation of the molecular hydrogen create high internal stresses within the steel that can greatly exceed the yield strength of a gy y g material and result in the formation of blisters. These blisters can often be visually observed on the exterior surface of steels in the form of an area of localized “swelling” They often resemble a “paint blister” but they are indeed localized swelling”. They often resemble a paint blister” but they are indeed a blister in the steel plate. Charlie Chong/ Fion Zhang

slide 89:

The best prevention for this type of cracking is to specify “HIC resistant material” when procuring steel plates. This material has substantially lower sulfur content usually 0.005 maximum sulfur and is commonly calcium- treated for sulfur shape control This lower sulfur content reduces the amount treated for sulfur shape control. This lower sulfur content reduces the amount of inclusions present in the steel thereby reducing the number of available sites for hydrogen to accumulate and form molecular hydrogen. The calcium treatments help to “round” any inclusions that may be present in the low sulfur steel thereby making it more difficult for hydrogen to enter. Charlie Chong/ Fion Zhang

slide 90:

Blistering H 0 + H 0 → H 2 Charlie Chong/ Fion Zhang

slide 91:

CONCLUSIONS It is the goal of design engineers and operators to prevent failures whether they are annoying seeps or catastrophic failures. It is a considerable economic benefit for users of steels to understand the environment in which economic benefit for users of steels to understand the environment in which that steel will be placed and the hazards associated with its exposure to that environment. By understanding the various forms of cracking that can occur yg g to steels the designer/operator can implement specification changes or modify the environment to eliminate that mechanism. This will extend the effective life of the equipment reduce the potential for failures reduce effective life of the equipment reduce the potential for failures reduce downtime associated with equipment repairs and make the production area safer with respect to equipment failure incidents. Charlie Chong/ Fion Zhang

slide 92:

It is vital when selecting a manufacturing/fabrication process to consider the preventative measures for reducing the susceptibility of steel to various forms of cracking. Some Regulatory agencies require that equipment be manufactured fabricated and maintained in a condition that is resistant to manufactured fabricated and maintained in a condition that is resistant to Sulfide Stress Cracking SSC. Therefore it is critical during the early stages of a project to specify “NACE” trim and “NACE” compliance on all equipment in a sour environment. However it must be noted that any modifications made to such equipment following its installation must be made such that this “NACE” condition is not negated NACE condition is not negated. By following the Standards published by NACE the designer/operator can be fid t th t th ifi d i t i t bl f i confident that the specified equipment is acceptable for use in a sour environment and is resistant to SSC. By applying the details found in the new International Standard NACE MR0175/ISO 15156: 2003 additional protection p from other forms of cracking can be integrated into the design specifications. Charlie Chong/ Fion Zhang

slide 93:

Further Reading g  https://www.engineersjournal.ie/2016/11/01/process-safety-failures-heat- exchangers/ exchangers/  https://www.slideshare.net/ArijitKarmakar1/htha-report-ioclpublish Charlie Chong/ Fion Zhang

slide 94:

Charlie Chong/ Fion Zhang

authorStream Live Help