Asme API 579 -1. ASME FFS-1 new edition 2021

Following changes have been implemented in the new edition 2021 of ASME API-579–1 // ASME FFS-1:

Part 2: Fitness-For-Service Engineering Assessment Procedure:

• Added provision that permits 𝑀𝐴𝑊𝑃 to be determined using the stress analysis procedures in Annex 2D.

Annex 2C: Thickness, 𝑀𝐴𝑊𝑃, and Stress Equations for an 𝐹𝐹𝑆 Assessment:

• Added Svensson method for burst pressure calculation.
• Removed option to use ASME VIII-2 allowable stress for ASME VIII-1 equipment. This was originally a carryover from API 510 before the allowable stress criteria in ASME VIII-2 changed from a factor of safety of 3.0 to a factor or safety of 2.4.
• Removed requirement for nozzle reinforcement check for small nozzles to be consistent with ASME VIII-1.
• Removed legacy limit load nozzle reinforcement procedure which was previously eliminated in ASME VIII-1.

Annex 2D: Stress Analysis Overview for an 𝐹𝐹𝑆 Assessment.

• Elastic load cases reference ASME VIII-2 for simplicity.
• Removed option to use ASME VIII-2 allowable stress for ASME VIII-1 equipment.
• Modified coefficients for use in elastic-plastic calculation to cover the appropriate design margins with various current and legacy construction codes (including the appropriate design margins for pipelines).
• Added explicit guidance on capping the yield stress used in a limit load analysis to the yield stress at temperature to prevent misapplication of the method when evaluating components fabricated from materials that have a design Code elastic allowable stress equal to 90% of the Minimum Specific Yield Stress (MSYS).
• Limited the allowable remaining strength factor, 𝑅𝑆𝐹𝑎, for buckling assessments to no lower than 0.9.

Annex 2E: Material Properties for Stress Analysis.

• Updated the Ramberg-Osgood stress-strain model for use in a Level 3 evaluation.
• Added guidance for material properties for Level 3 evaluations involving pipeline materials.
• Updated correlations for estimating material Ultimate Tensile Strength (𝑈𝑇𝑆) using hardness testing.

Part 3: Assessment of Existing Equipment for Brittle Fracture.

• Clarified that the use of design codes/standards as an alternative to Part 3 is considered a Level 3 Assessment.
• Corrected errors related to the Minimum Allowable Temperature (𝑀𝐴𝑇) for bolting and nut material specifications.
• Expanded the definition of shock chilling and added the requirement that a Level 3 evaluation is necessary to evaluate conditions where the shock chilling screening is not satisfied.
• Added thickness limits for Level 1 impact test exemption curves to be consistent with ASME VIII-1.
• Clarified that no 𝑃𝑊𝐻𝑇 credit is permitted in a brittle fracture evaluation of a component if previous repairs were completed using alternative weld methods (such as high preheat or temper bead).
• Added supplemental inspection requirements for brittle fracture evaluations performed on component identified to have metal loss that exceeds the original design tolerances.
• Explicitly excluded mill tolerance effects in a brittle fracture assessment.
• Modified impact test exemptions for flanges to address recent changes to ASME VIII-1.
• Added requirement that components not exposed to general primary membrane tensile stress shall be evaluated using the pressure rating basis in a Level 2 Assessment.

Part 4: Assessment of General Metal Loss.

• Moved component type definitions and examples to a table to simplify designations.
• Exempted the cylinder side of 2:1 elliptical head-to-shell junctions as Type C components and structural discontinuities for metal loss assessments (applicable to Part 4, Part 5, and Part 6 Assessments).
• Revised qualifications to utilize Point Thickness Reading (PTR) approach to prevent misapplication of the method and “washing out” of local damage.
• Revised length for thickness averaging at nozzles (Figure 4.13) to ensure method does not permit greater damage at nozzle junctions vs. away from nozzle junctions.
• Revised recommended UT grid spacing for scenarios when “corroded surface is not accessible for visual inspection, 𝐿𝑠 = min[2𝑡𝑟𝑑 , 25 𝑚𝑚 (1 𝑖𝑛𝑐ℎ)].
• Documented the purpose of the minimum measured thickness limit in Level 1 and Level 2 Assessments.
• Included recommendations for validation of inspection results when thickness readings are less than or equal to 2.5 mm (0.100 inches) (also referenced in Part 5 Assessment of Local Wall Loss and Part 6 Assessment of Pitting).

Part 9: Assessment of Crack-Like Flaws.

• Redefined crack-like flaw interaction and recategorization rules to reduce conservatism and for better alignment with ASME Section XI.
• Table 9.2 updated to reflect new Wallin Master Curve fracture toughness correlation for carbon and low alloy steels in Annex 9F.

Annex 9B: Compendium of Stress Intensity Factor Solutions for Crack-like Flaws.

• Expanded K-solutions to cover thick-wall cylinders.

Annex 9C: Compendium of Reference Stress Solutions for Crack-like Flaws.

• Updated solutions for circumferential flaws in cylinders.
• Expanded reference solutions to cover thick-wall cylinders.

Annex 9F: Material Properties for Crack-like Flaws.

• Updated Wallin Master Curve fracture toughness correlation for carbon and low alloy steels.
• Added ductile tearing material property data. The data was included in the 2007 edition of API 579, but mistakenly removed in the 2016 edition.
• Updated guidance on fracture toughness estimates for stainless-steel base metal and welds.
• Incorporated guidance from WRC Bulletin 562 Recommendations for Establishing the Minimum Pressurization Temperature (MPT) for Equipment and the API white paper The Effects of Hydrogen for Establishing a Minimum Pressurization Temperature (MPT) for Heavy Wall Steel Reactor Vessels to address material toughness modifications due to hydrogen and temper embrittlement effects.
• Added guidance for ASME VIII-3 equipment (high pressure).

New Annex 9H: Constraint Effects for Surface Flaws in Carbon and Low-Alloy Steel Components in the Ductile-Brittle Transition Region.

• Established a procedure to adjust material fracture toughness to take advantage of constraint effects for surface flaws in a Level 2 Assessment.
• Technical basis is documented in WRC Bulletin 577 Constraint Effects on Fracture Toughness in Ductile-Brittle Transition.

New Annex 9I: Alternative Estimate of Mode I Stress Intensity Factors.

• Established a procedure to adjust material fracture toughness to take advantage of constraint effects for surface flaws in a Level 2 Assessment.
• Technical basis is documented in WRC Bulletin 577 Constraint Effects on Fracture Toughness in Ductile-Brittle Transition.

New Annex 9J: Determination of the Minimum Allowable Temperature (MAT) using a Fracture Mechanics Approach.

• Established procedure for using fracture mechanics to determine the 𝑀𝐴𝑇.
• Included a simplified brittle fracture screening procedure developed using fracture mechanics.
• Provided guidance on the necessary adjustments for 2.25Cr-1Mo steel in hydrogen service.

Part 10: Assessment of Components Operating in the Creep Range.

• Updated Level 1 screening curves to ensure consistency with results from a Level 2 Assessment and incorporate technology updates (updated material coefficients, etc.).
• Revised Level 1 maximum permissible damage limit to 0.8 in the evaluation of multiple operating conditions.
• Add structural thickness limit to Level 1 and Level 2 Assessments to protect against loss of containment due to the challenges and limitations associated with inspection of furnace tubes.

Annex 10B: Material Data for Creep Analysis.

• Updated existing and added new MPC Omega material coefficients.
• Added WRC Bulletin 541 revision 3 Larson-Miller material coefficients.
• Fixed elevated temperature fatigue curve coefficients.

Part 11: Assessment of Fire Damage.

• Extended the use of hardness testing to cover carbon steel, low chrome, and stainless-steel materials.

Part 12: Assessment of Dents, Gouges, and Dent-Gouge Combinations.

• Updated Level 1 and Level 2 procedures, applicability and limitations, and acceptance criteria to align with The Pipeline Defect Assessment Manual (PDAM).
• Table 12.2 updated to reflect new Wallin Master Curve fracture toughness correlation for carbon and low alloy steels in Annex 9F.

Part 14: Assessment of Fatigue Damage.

• Added closed-form equation for smooth bar fatigue curves and data for new materials.
• Added smooth bar fatigue curves based on fatigue testing in air.
• Added bounds for use of smooth bar fatigue curve equations.
• Updated fatigue screening Method C and Method D.
• Corrected plasticity correction factor, 𝐾𝑒,𝑘.
• Elastic ratcheting procedure re-written using Bree Diagram.
• Updated Level 2 procedure for Method C Fatigue Assessment.

Annex 14B: Material Properties for Fatigue Analysis.

• Added closed-form equation for smooth bar fatigue curves and added data for new materials.
• Added smooth bar fatigue curves based on fatigue testing in air.
• Added bounds for use of smooth bar fatigue curve equations.