In such cases, the tests and acceptance criteria shall be agreed with the equipment user. The AYS shall be as defined in the product specification or the 0. Control to within a range of 0,1 pH units is achievable in practice.
When evaluating welds, 7. Alternative tests are under development. The equipment user may choose other tests at his discretion. The justification of the use of such tests shall be documented. Steels selected using A. For small-scale testing of welds, specimens shall be taken transverse to the weld. Measure the tensile strength of the specimen. No ladder-like HIC indications nor cracks exceeding a length of 0.
Below any magnetic particle indications running perpendicular to the stress axis, metallographic sectioning shall be made perpendicular to the indications or, in the absence of magnetic particle indications, at least two metallographic sections shall be made parallel to the stress axis of the specimen. No ladder-like HIC features nor cracks exceeding a length of 0. It is sometimes considered that such stresses in field situations are better represented in large-scale specimens.
Such tests may be required to improve confidence in the results obtained. Other acceptance criteria may be agreed between the supplier and the equipment user. If the system total pressure and concentration of H2S are known, H2S partial pressures can also be estimated using Figure C. NOTE For a liquid-full pipeline downstream of gas separation units, a good approximation for bubble-point pressure is the total pressure of the last gas separator. This value can be used to determine whether a system is sour in accordance with option 1 see 7.
Figures D. In Figures D. The in situ pH can also be influenced by the presence of organic acids, such as acetic acid, propionic acid, etc. The importance of the influences of these acids on in situ pH and on the results of conventional water analyses are described in EFC Publication 17, Appendix 2.
Analysis for these components should be made in order to make the necessary adjustments to the calculated in situ pH. Clause 8 b Material for specific sour- and B. Table B. UT test specimens by Table B. Description of test Default values per conditions Table B. Practical aspects of the influence of in situ pH on H2S-induced cracking. In more recent editions, NACE MR has also provided application limits for some corrosion-resistant alloys in terms of environmental composition and pH, temperature, and H2S partial pressures.
These documents are generally complementary to those of NACE, though they differed in scope and detail. The changes were developed by and approved by the ballot of representative groups from within the oil and gas production industry. It is the equipment user's responsibility to select the CRAs and other alloys suitable for the intended service. It can be applied to help avoid costly corrosion damage to the equipment itself. It supplements, but does not replace, the materials requirements of the appropriate design codes, standards, or regulations.
These limits are dependent on the material type or the individual alloy. In defining the severity of H2S-containing environments, exposures that can occur during system upsets or shutdowns, etc. Such exposures can include unbuffered, low pH condensed water. The limits given in the tables in Annex A are for production environments and do not cover conditions occurring during injection or flowback of chemicals that can reduce the in situ pH.
CRAs and other alloys shall be selected using Annex A or following qualification by successful laboratory testing in accordance with Annex B. Qualification based on satisfactory field experience is also acceptable. In Annex A, materials are identified by materials groups. Within each group, alloys are identified by materials type within compositional limits or as individual alloys.
Acceptable metallurgical conditions and environmental limits are given for which alloys are expected to resist cracking. Environmental limits are given for H2S partial pressure, temperature, chloride concentration, and elemental sulfur. A CRA or other alloy can be qualified by testing for use under operating conditions that are more severe than the environmental limits given in Annex A. Similarly, a CRA or other alloy can be qualified for use in different metallurgical conditions higher strength, alternative heat treatment, etc.
The equipment user shall verify qualifications see B. The user may establish the required conversion tables. Welded joints can have a greater susceptibility to cracking than the parent material s joined. The equipment user may allow the cracking susceptibility of weldments to govern the limits of safe service conditions for a fabricated system. Processes and consumables used in welding should be selected in accordance with good practice and to achieve the required corrosion and cracking resistances.
Welding PQRs shall include documented evidence demonstrating satisfactory cracking resistance under conditions at least as severe as those of the proposed application. Such evidence shall be based upon one or more of the following: — compliance with the requirements and recommendations for the specific materials group of Annex A see also 6.
The requirements and recommendations given in Annex A might not be appropriate for all combinations of parent and weld metals used in the fabrication of equipment and components. The equipment user may require evidence of successful cracking-resistance testing as part of the welding procedure qualification to ensure the weldment produced provides adequate resistance to SSC, SCC, and GHSC for the application.
The use of other methods shall require explicit user approval. Hardness acceptance criteria can also be established from successful cracking-resistance testing of welded samples. Testing shall be in accordance with Annex B. Qualification testing shall be specified as part of the qualification of burning and cutting processes if any HAZ remains in the final product.
The requirements and acceptance criteria of 6. The form and location of the samples used for evaluation and testing shall be acceptable to the equipment user. With the absolute method, an observed value or a calculated value is not to be rounded, but is to be compared directly with the specified limiting value.
Conformance or non-conformance with the specification is based on this comparison. Nominal composition is used for general classification only. Though useful, these indices are not directly indicative of corrosion resistance in H2S-containing oil field environments.
If the purchaser intends to make use of such agreements, extensions, and qualifications, the appropriate additional information shall be clearly indicated in the materials purchasing specification. Suggested formats are given in Annex C. The tables in Annex C provide designations that can be used. Subject to A. Information on the use of copper and aluminium alloys is contained in A.
These subclauses also often contain materials selection tables showing the less restrictive environmental limits of the materials when used for named equipment or components. These limits apply 2 collectively. The pH used in the tables corresponds to the minimum in situ pH. In US Customary units, these are commonly expressed in parts per million ppm.
NOTE 4 In preparing the materials selection tables, it is assumed that no oxygen is present in the service environment. Where no specified limit for a variable can be defined in a table, explanatory remarks that reflect current knowledge have been included in the table. The environmental limits for an alloy are valid only within any additional metallurgical limits given for the alloy in the text of the same table.
Where tempering of a material is required, the tempering time shall be sufficient to ensure the achievement of the required through-thickness hardness. When purchasing materials, metallurgical properties known to affect the materials' performance in H2S- containing oil and gas environments in addition to those specifically listed in this Annex should also be considered.
For the composition, cracking-resistance and use of overlays, see A. Metallic coatings electroplated and electroless plated , conversion coatings, plastic coatings, or linings may be used, but are not acceptable for preventing cracking. The effect of their application on the cracking-resistance of the substrate shall be considered. Nitriding with a maximum case depth of 0. The use of nitriding as a means of preventing cracking in sour service is not acceptable.
The use of conventional sharp V-stamping is acceptable in low-stress areas such as the outside diameter of flanges. Conventional sharp V-stamping shall not be performed in high-stress areas unless agreed with the equipment user.
It also provides a guide to additional materials selection tables for specific named equipment or components when other, less restrictive, environmental, or metallurgical limits may be applied. Other alloying elements are permitted. Higher carbon contents for UNS S and S are acceptable up to the limits of their respective specifications. The alloys listed in Table D. In some cases, more restrictive chemistries are required to comply with the requirements of this materials group.
See also A. It is common industry practice to dual certify series stainless steels as standard grade and low carbon grade such as S and S L. The environmental limits given for low carbon series stainless steels are acceptable for the dual certified grades. Free-machining austenitic stainless steel products shall not be used. The stress corrosion cracking resistance of all austenitic stainless steels of the material type described in A. The following conditions shall apply: — the material shall be free from cold work caused by shaping, forming, cold reducing, tension, expansion, etc.
For these applications, the following material restrictions shall also apply: — UNS S at a maximum hardness level of 35 HRC may be used in the cold-worked condition provided this cold working is preceded by solution annealing. No limits on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.
UNS S stainless steel may be used for compression fittings and instrument tubing even though it might not satisfy the requirements stated for any equipment or component in Table A.
For these applications, the following materials restrictions shall apply; — J, J API compression seal rings and gaskets made of centrifugally cast material in the as-cast or solution-annealed condition shall have a hardness of HBW 83 HRB maximum; — S, S, S or S API compression seal rings and gaskets made of wrought material in the solution- annealed condition shall have a hardness of HBW 83 HRB maximum.
For these applications, these materials shall also — be in the solution-annealed and quenched or annealed and stabilized heat-treatment condition, — be free of cold work intended to enhance their mechanical properties, and — have a maximum hardness of 22 HRC. A limit on the martensite content of these austenitic stainless steels should be considered. The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable.
Weldments may be repair-welded if they meet the welding procedure requirements. However, in some cases, this requires production within more restricted ranges of chemical analysis than those specified in Table D. Austenitic stainless steels included in Table D. Free-machining highly alloyed austenitic stainless steels shall not be used. All the above alloys shall be in the solution-annealed and cold-worked condition with a maximum hardness of 35 HRC.
The symbol w represents the percentage mass fraction of the element indicated by the subscript. Wrought N for use as instrument tubing shall be in the annealed condition with a maximum hardness of HV The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable.
Weldments may be repair-welded if they meet the weld procedure requirements. Table D. In some cases, more restrictive compositions than those shown in Table D. Wrought or cast solid-solution nickel-based products made from alloys of types 4a and 4b shall be in the solution-annealed or annealed condition. Wellhead and christmas tree components shall also be in accordance with ISO N bearing pins, e. No limits column column column column on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.
There are no hardness requirements for welding solid-solution nickel-based alloys with solid-solution nickel-based weld metal. These materials shall be in the annealed condition and shall have a maximum hardness of 22 HRC. Hardness testing of qualification welds shall be carried out and the maximum hardness shall be HV or, if a different hardness test method is permitted, its equivalent. No S limits on these parameters are set, but some combinations of their values might not be acceptable.
Martensitic stainless steels welded with nominally matching consumables shall meet the following requirements. In some cases, more restrictive chemistries than those shown in Table D. NOTE Higher values of FPREN provide higher corrosion resistance; however, they also lead to increased risk of sigma- and alpha- prime phase formation in the materials' ferrite phase during manufacture depending on product thickness and achievable quench rate.
The ranges of FPREN quoted are typical of those found to minimize the problem of sigma- and alpha-prime phase formation. The presence of deleterious phases can reduce the cracking-resistance of duplex stainless steels. Any combination of temperature and in situ pH occurring in See See production environments Chloride column column limits have been found to be strongly dependent upon yield strength and the level of cold work.
A cross-section of the weld metal, HAZ, and base metal shall be examined as part of the welding procedure qualification. Intermetallic phases, nitrides, and carbides shall not exceed 1. The sigma phase shall not exceed 0. Austenitic precipitation-hardened stainless steels are addressed in Table A.
Martensitic precipitation-hardened stainless steels are addressed in Table A. UNS S shall have a maximum hardness of 35 HRC and shall be in either the solution-annealed and aged or solution-annealed and double-aged condition. Environmental limits for this alloy for these applications have not been established.
The hardness of the base metal after welding shall not exceed the maximum hardness allowed for the base metal and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective metal for the weld alloy.
For these applications, this material shall also comply with the following. Wrought UNS N shall have a maximum hardness of 35 HRC and shall be either a hot-worked and age-hardened, b solution-annealed, or c solution-annealed and age-hardened. For these applications, these materials shall also comply with the following: a wrought UNS N shall have a maximum hardness of 35 HRC and shall be either 1 solution-annealed and aged, 2 solution-annealed, 3 hot-worked, or 4 hot-worked and aged.
No limits on individual parameters are set, but some combinations of the values of these parameters have led to field failures. For this application these materials shall also comply with the following: — UNS N springs shall be in the cold-worked and age-hardened condition and shall have a maximum hardness of 50 HRC; — UNS N can be used for springs for compressor valves in the cold-worked and age-hardened condition with a maximum hardness of 50 HRC.
May Petroleum and natural gas industries - Materials for use in H2S-containing environments in oil and gas production - Part 2: Cracking-resistant carbon and low-alloy steels, and the use of cast irons.
Our policy towards the use of cookies Techstreet uses cookies to improve your online experience. They were placed on your computer when you launched this website. Discussion: Thermal gradient External thermal gradient?
Thermal gradient during processing? Such ch soft zones ones are ttypically picall associated with ith welds elds in carbon steels 3. Keywords: K d soft zones can yield and accumulate plastic strain locally Ponder? The linking of hydrogen-induced cracks to produce stepwise cracking is dependent on the local strain between the cracks and the embrittlement of the surrounding steel by dissolved hydrogen. It has been observed in parent material of longitudinally welded ld d pipe i and d iin the h heat-affected h ff d zone HAZ 3.
SOHIC is a relatively uncommon phenomenon usually associated with low-strength ferritic pipe and pressure vessel steels. It has been observed in parent material of longitudinally welded pipe and in the heat- heat affected zone HAZ 3. Hydrogen uptake is promoted in the presence of sulfides.
The atomic hydrogen can diffuse into the metal, reduce ductility, and increase susceptibility to cracking. Hydrogen uptake is promoted in the presence of sulfides sulfides. High-strength metallic materials and hard weld zones are prone to SSC.
No externally applied stress is required for the Cracking g formation of hydrogen-induced y g cracks. If necessary, the equipment user should advise other parties of the service conditions. Keywords: f the for h material i l selected l d iin the h condition di i iin which hi h iit enters iinto service. The defined conditions shall include both intended exposures and unintended exposures that can result from the failure of primary containment or protection methods.
Particular attention shall be paid to the quantification of those factors known to affect the susceptibility of materials to cracking caused by H2S. Factors, other than material properties, known to affect the susceptibility of metallic materials to cracking in H2S service include: 1 H2S partial pressure, 2 in situ pH, 3 the concentration of dissolved chloride or other halide, 4 the presence of elemental sulfur or other oxidant, 5 temperature, 6 galvanic effects, effects 7 mechanical stress, and 8 time of exposure to contact with a liquid water phase.
Generally, no additional laboratory testing of materials selected in these ways is required The materials listed have given acceptable performance under the stated required. The equipment user should, nevertheless, give consideration to specific testing of materials for applications where they consider the potential consequences of failure make this justifiable see WARNING.
The tolerances or ranges of properties that can occur within the material shall be described and documented. Metallurgical properties known to affect performance in H2S-containing environments include: 1 chemical composition, 2 method of manufacture, 3 product form, 4 strength, 5 hardness hardness, 6 amount of cold work, 7 heat treatment condition, and 8 microstructure. The description of the service conditions in which the experience has been gained shall meet the relevant requirements of 6.
The duration of the documented field experience shall be at least two years and should preferably involve a full examination of the equipment following field use. Comments: Where does the MR specified stress level and test temperature? The test samples shall be representative of the commercial product. For multiple batches of a material produced to a single specification, an assessment shall be made of the properties that influence cracking behavior in H2S S-containing containing environments see 8 8.
The materials in the metallurgical condition that has the greatest susceptibility to cracking in H2S service shall be used for the selection of the test samples. For qualification of a material for use in application-specific application specific service conditions, the equipment user shall take care to ensure that the test conditions and the test results obtained from them are appropriate for those specific service conditions.
The p pH applied pp shall represent p the service in situ p pH. The justification of the selection of the 1 test environment and 2 mechanical test conditions? Question: What is mechanical test conditions? The equipment user shall be responsible for ensuring that the required documentation is prepared.
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