Other test methods require the agreement of the equipment user. This differs from previous editions where HRC was the primary basis of acceptance. Previous standard versions only considered SSC as the governing cracking mechanism. For example, austenitic stainless steels e. In previous editions, only sulfide stress cracking SSC was considered; there were no temperature restrictions. In previous editions of MR, several legacy materials had no environmental restrictions, implying they were suitable for any sour service environment.
For example, wrought precipitation hardening nickel alloy UNS N had no environmental restrictions in previous editions of MR; in the current standard this alloy has H2S partial pressure limitations based on the maximum operating temperature. The environmental limits listed in Tables A. For example, austenitic steels such as AISI are limited to a maximum of kPa partial pressure of H2S at a maximum temperature of 60oC for any combination of chloride concentration and in situ pH in the production fluid.
These categories or materials groups austenitic steel, martensitic steels, etc are further split into material types similar compositional limits and individual alloys. For example, Annex A, Table A. This table is sectioned into general materials type and individual alloys, e. UNS S The individual alloys tend to have broader environmental limits than those set for the group. Suitable labeling or documentation is also acceptable. A summary of the content described below is presented in a flowchart diagram in Appendix B, see Appendix B.
For design using plastic criteria strain—based and limit states use of this standard may not be appropriate. Note: All items in this section are repeated in both Part2 and Part3 of the standard. Clause 6. Clause 8. Testing may be conducted under service conditions similar to the limits applied to pre-qualified materials or under service conditions outside these limits. The parameters affecting the behavior of carbon and low alloy steels in H2S environments are explicitly listed metallurgy, H2S partial pressure, pH, chloride content, etc.
The user must evaluate the severity of the service environment based on a combination of H2S partial pressure and in service pH. Any other test method requires explicit user approval. Clause 7. Hardness testing shall be specified as part of the qualification for fabrication methods such as burning and cutting if any HAZ remains in the final product. To address this prospect, additional testing and specific acceptance criteria may be required.
A description of the process by which these changes were approved can be found at the ISO maintenance website www. It is the equipment user's responsibility to select materials suitable for the intended service.
It can be applied to help to avoid costly corrosion damage to the equipment itself. For design utilizing strain- based design methods, see Clause 5. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document including any amendments applies.
No externally applied stress is required for the formation of hydrogen-induced cracks. This form of hydrogen-induced cracking is not related to welding. Such soft zones are typically associated with welds in carbon steels 3.
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 pipe and in the heat-affected zone HAZ 3. SOHIC is a relatively uncommon phenomenon usually associated with low-strength ferritic pipe and pressure vessel steels.
Hydrogen uptake is promoted in the presence of sulfides. The atomic hydrogen can diffuse into the metal, reduce ductility, and increase susceptibility to cracking. High-strength metallic materials and hard weld zones are prone to SSC. If necessary, the equipment user should advise other parties of the service conditions. Qualification, with respect to a particular mode of failure, for use in defined service conditions also qualifies a material for use under other service conditions that are equal to or less severe in all respects than the conditions for which qualification was carried out.
It is the equipment user's responsibility to ensure that any material specified for use in their equipment is satisfactory in the service environment. 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 H2S partial pressure, in situ pH, the concentration of dissolved chloride or other halide, the presence of elemental sulfur or other oxidant, temperature, galvanic effects, mechanical stress, and time of exposure to contact with a liquid water phase.
Generally, no additional laboratory testing of materials selected in these ways is required. 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 chemical composition, method of manufacture, product form, strength, hardness, amount of cold work, heat- treatment condition, and microstructure.
The material description shall meet the requirements of 8. 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. The severity of intended service conditions shall not exceed that of the field experience for which documented records are available.
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 behaviour in H2S-containing environments see 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.
Materials source, method of preparation, and surface condition of samples for testing shall be documented. For qualification of a material for use in 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.
All the test conditions applied shall be at least as severe, with respect to the potential mode of failure, as those defined to occur in the field service see 6. The pH applied shall represent the service in situ pH. The justification of the selection of the test environment and mechanical test conditions with respect to a specific application shall be documented by the equipment user. The equipment user shall be responsible for ensuring that the required documentation is prepared.
The changes were developed by and approved by the ballot of, representative groups from within the oil and gas production industry. A description of the process by which these changes were approved can be found at the ISO maintenance Web site: www. It is the equipment user's responsibility to select the carbon and low-alloy steels and cast irons suitable for the intended service.
It supplements, but does not replace, the materials requirements of the appropriate design codes, standards or regulations. Loss of material by general mass loss or localized corrosion is not addressed. 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.
This information may include — requirements for SSC testing see 7. Suggested formats are given in Annex E. Normally, no special precautions are required for the selection of steels for use under these conditions, nevertheless, highly susceptible steels can crack. Additional information on factors affecting susceptibility of steels and attack by cracking mechanisms other than SSC is given in 7.
For a given material, the limits of environmental and metallurgical variables defined for specific sour service or for a range of sour service by qualification in accordance with Option 2 may replace any limits of environmental and metallurgical variables listed for that material in A. Steels for other equipment may also be qualified.
In some cases, this requires an agreement between the supplier and the equipment user with respect to test and acceptance requirements. Such agreements shall be documented. Option 2 can also facilitate fitness-for-purpose evaluations of existing carbon or low-alloy steel equipment exposed to sour-service conditions more severe than assumed in the current design. Nevertheless, a number of factors, as follows, that can affect a steel's performance in this region should be considered.
Above about MPa ksi yield strength, attention should be given to steel composition and processing to ensure that these steels do not exhibit SSC or HSC in region 0 environments. In the absence of suitable choices from Annex A, carbon and low-alloy steels may be tested and qualified for use under specific sour-service conditions or for use throughout a given SSC region. NOTE The occurrence of these phenomena is rare and they are not well understood.
Their occurrence is thought to be restricted to carbon steels. The presence of sulfur or oxygen in the service environment is thought to increase the probability of damage by these mechanisms. Hardness control can be an acceptable means of obtaining SSC resistance. Other conversion tables also exist. Users may establish correlations for individual materials. Processes and consumables should be selected in accordance with good practice and to achieve the required cracking resistance.
Welding shall be carried out in compliance with appropriate codes and standards as agreed between the supplier and the purchaser.
Welding procedure specifications WPSs and procedure qualification records PQRs shall be available for inspection by the equipment user. The qualification of welding procedures for sour service shall include hardness testing in accordance with 7.
The HRC method may be used for welding procedure qualification if the design stress does not exceed two- thirds of SMYS and the welding procedure specification includes post-weld heat treatment.
The use of the HRC method for welding procedure qualification in all other cases shall require the agreement of the equipment user. NOTE Hardness surveys using the Vickers or Rockwell 15N testing method produce a more detailed picture of weld hardness and its variations.
Hardness surveys using the HRC testing method might not detect small zones in welds or HAZs where the hardness exceeds the acceptance criteria for the Vickers or Rockwell 15N testing method. The significance of such small hard zones is not well understood. The use of other hardness testing methods shall require the agreement of the equipment user. The Vickers or Rockwell 15N hardness testing method shall be used for the qualification of alternative weld- hardness acceptance criteria as permitted in 7.
HRC surveys of butt welds shall be in accordance with Figure 5. Survey requirements for other joint configurations shall be developed from these figures. Hardness surveys for qualification of overlay welding procedures shall be in accordance with Figure 6.
Figure 6 — Weld overlay 7. Alternative weld hardness acceptance criteria may be established from successful SSC testing of welded samples. SSC testing shall be in accordance with Annex B. The requirements, interpreted for the fabrication method, and hardness acceptance criteria of 7. The form and location of the samples for evaluation and testing shall be acceptable to the equipment user. The level of sulfur in the steel is of particular importance, typical maximum acceptable levels for flat-rolled and seamless products are 0.
Conventional forgings with sulfur levels less than 0. NOTE 2 The presence of rust, sulfur, or oxygen, particularly together with chloride, in the service environment is thought to increase the probability of damage.
Suitable labelling or documentation is also acceptable. For materials qualified and selected for a special application in accordance with Annex B, traceability shall include reference to the environmental conditions of the special application.
Table E. Requirements for the use of cast irons are given in A. NOTE A. Therefore, A. Nevertheless, any SSC testing that forms part of a materials manufacturing specification shall be carried out successfully and the results reported. The majority of steels that comply with the general requirements of A. The hardness limit of HRC 22 applied to most carbon and low-alloy steels is based on correlations of heat treatment, chemical composition, hardness and failure experience.
The higher hardness limits for the chromium-molybdenum steels are based on similar considerations. NOTE 2 It can be possible to qualify a carbon or low alloy steel not described or listed in the text or tables of A.
Acceptable maximum hardness values for carbon steel, carbon manganese steel and low alloy steel welds are given in Table A. As-welded carbon steels, carbon-manganese steels and low-alloy steels that comply with the hardness requirements of Table A. For these products, hardness testing of welding procedures may be waived if agreed by the equipment user.
The conditions in Table A. Carbon steel, carbon manganese and low-alloy steel weldments that do not comply with other paragraphs of this subclause shall be post weld heat treated after welding. The heat treatment temperature and its duration shall be chosen to ensure that the maximum weld zone hardness, determined in accordance with 7. Metallic coatings electroplated and electroless plated , conversion coatings, plastic coatings and linings are not acceptable for preventing SSC.
Overlays applied by thermal processes such as welding, silver brazing, or spray metallizing systems are acceptable if they comply with one of the following requirements. Joining of dissimilar materials, such as cemented carbides to steels by silver brazing, is acceptable.
Nitriding, with a maximum case depth of 0. Thermal stress relief shall be performed in accordance with an appropriate code or standard. SSC testing and qualification in accordance with Annex B may be used to justify other cold deformation limits.
Threads produced by cold forming rolling are acceptable in steels that otherwise comply with the heat treatment and hardness requirements of A. The use of conventional sharp V-stamping is acceptable in low-stress areas, such as the outside diameter of flanges.
The Canadian Association of Petroleum Producers CAPP represents companies that explore for, develop and produce natural gas, natural gas liquids, crude oil, oil sands, and elemental sulphur throughout Canada. CAPP member companies produce more than 95 per cent of Canadas natural gas and crude oil.
CAPP also has associate members that provide a wide range of services that support the upstream crude oil and natural gas industry. The responsibility for safe application of alloys is defined as follows: Manufacturers and suppliers provide materials that meet: NACE MR minimum metallurgical requirements chemistry, mechanical properties, hardness, and processing USER - specified additional metallurgical requirements Users are responsible for the materials selection and defining the environment Oil company Contractor if delegated Service if delegated NOT the manufacturer or supplier materials and components.
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