The guidelines provided in this standard may be used to make runrepair- replace decisions to help determine if pressurized equipment containing flaws that have been identified by inspection can continue to operate safely for some period of time. Downstream Segment American Petroleum Institute, Ninth Edition , June General Application Coverage This inspection code covers the in-service inspection, repair, alteration, and rerating activities for pressure vessels and the pressure- relieving devices protecting these vessels. This inspection code applies to all refining and chemical process vessels that have been placed in service unless specifically excluded per 1. This incl It provides minimum requirements for maintaining the integrity of such tanks after they have been placed in service and addresses inspection, repair, alteration, relocation, and reconstruction.
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The last version of API was issued in , so upgrades have been 9 years in the making. There are many small corrections and tweaks and a few big changes as well. The most conspicuous change in the edition may be the Table of Contents. Previously, most of the reference information required in the analyses was relegated to the many Annexes located in the back of the document. Now, every Annex has been repositions to appear after the Part to which it applies. For example, the reference stress solutions for crack-like flaws appear in Annex 9C after Part 9 , rather than in Annex D.
No change in substance here…you just need to learn where to look. The expansion of applicable codes is a good thing. It provides direct support for the use of API in an expanded set of environments.
This can be increasingly important when dealing with jurisdictions or if a failure winds up in the courts. One of the big changes in is the addition of a new Part on fatigue assessment.
But this may not be quite as big a change as it might seem since fatigue assessment was already included in Annex B1. One personal observation on the new Part 14 Level 2 assessment is that it involves a fairly complicated set of calculations. So there is likely to be a tendency for fatigue calculations to be performed primarily by specialists. Partial Safety Factors in Flaw Assessment. One of the biggest changes is in the way the crack-like flaw assessment Part 9 handles safety factors.
But first, what are partial safety factors? Traditional safety factors are applied at the end of a calculation. If we calculate the stress to be 10 ksi, and we want a safety factor of 3 on yield, we need a material with a yield stress of 30 ksi.
Partial safety factors PSFs are safety factors applied to several inputs of a calculation. For example, we might apply one safe factor to the moment, M and a different factor to the dimension, c.
The selection of these safety factors is typically related to the uncertainty in the input parameter and in the acceptable probability of failure. In the Level 2 assessment, partial safety factors were applied to three parameters: flaw size, material toughness, and stress.
The user made choices and calculations related to the uncertainties and acceptable probability of failure. Once these selections were made, the PSFs were applied to the inputs, before the calculations were performed.
Closer reading introduces a few subtleties, but Annex 9A. Alternatively, mean values of these parameters may be used with Partial Safety Factors. If conservative lower bound values are used for the input values in the assessment, PSFs are not needed as they similarly were not need under the edition.
If, on the other hand, mean values are used, PSFs remain appropriate. But, in my opinion, routinely ignoring the PSFs i. Unfortunately, the version provides no guidance on what factors to use. Remember, joint efficiency is a knock-down factor to account for overall weld quality.
The fracture mechanics analysis is explicitly evaluating the flaw. Remaining Strength Factors. This section discusses the differences in the Burst Pressure Ratio i. If a constant burst pressure ratio is adopted, different construction codes will have different RSFs. Modification to RSF may also be based on other factors such as loading or consequence of failure. Part 5 of the version carves out a simpler and more restrictive definition of a Type A component and uses that to provide and a simpler Level 1 local thin area assessment procedure.
This change provides a somewhat simpler Level 1 procedure which eliminated the Tensile Stress Factor TSF in evaluating the circumferential extent of cylindrical shells, conical shells, and elbows. Metallurgical Investigation of Fire Damage. A new Annex 11B is included to provide guidance on the use of metallurgical techniques in the assessment of fire damage.
This annex provides guidelines for both performing a metallurgical investigation and interpreting the results. It is limited to carbon, low alloy, and stainless steels.
I think that this annex can be considered an overview and introduction to metallurgical techniques for the non-metallurgists. Another section on the interpretation of test results paragraph 11B.
Taken as a whole, this section may provide significant insight, particularly to an inexperienced non-metallurgical engineer. Creep Assessment. While the basic remaining life calculation methodology is unchanged, there have been several changes to the creep procedure of Part The residual stress section has been the subject of substantial work since the release of the edition. This has been prompted by recent improvements in the simulation of weld residual stress, which provides an opportunity for improvement.
This revision includes changes in equations and calculations, a greater emphasis on heat input, and numerous other changes, but the average user may not directly interact with this annex in great depth. There are many, many other small changes throughout, some just editorial and some substantial, but I believe this brief summary covers the most important. Many small changes are present throughout. Greg Garic has over thirty-five years of experience in analysis and fitness-for service assessment.
He has spent most of his career working in the areas of structural integrity assessment and remaining life evaluation of pressure vessels and piping. He is also an associate editor of several PVP volumes relating to fracture mechanics and fitness-for-service issues. You must Register or Login to post a comment. Stress A-Z Index.
Toggle navigation. Reorganization The most conspicuous change in the edition may be the Table of Contents.
Fatigue Assessment One of the big changes in is the addition of a new Part on fatigue assessment. Partial Safety Factors in Flaw Assessment One of the biggest changes is in the way the crack-like flaw assessment Part 9 handles safety factors. The following Table provides a summary of the component type definitions in and Metallurgical Investigation of Fire Damage A new Annex 11B is included to provide guidance on the use of metallurgical techniques in the assessment of fire damage.
Creep Assessment While the basic remaining life calculation methodology is unchanged, there have been several changes to the creep procedure of Part Residual Stress The residual stress section has been the subject of substantial work since the release of the edition. Conclusion There are many, many other small changes throughout, some just editorial and some substantial, but I believe this brief summary covers the most important.
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API 579 / ASME FFS
API 579-2 FITNESS-FOR-SERVICE EXAMPLE PROBLEM MANUAL