A Tiered Approach to Girth Weld Defect Acceptance Criteria for Stress-Based Design of Pipelines

2006 ◽  
Author(s):  
Yong-Yi Wang ◽  
Ming Liu ◽  
David Horsley ◽  
Gery Bauman
Keyword(s):  
Test Data ◽  
Plastic Collapse ◽  
Department Of Transportation ◽  
Acceptance Criteria ◽  
Weld Defect ◽  
The Us ◽  
Welding Procedure ◽  
Assessment Procedures ◽  
Technical Basis ◽  
New Procedures

Alternative girth weld defect acceptance criteria implemented in major international codes and standards vary significantly. The requirements for welding procedure qualification and the allowable defect size are often very different among the codes and standards. The assessment procedures in some of the codes and standards are more adaptive to modern micro-alloyed TMCP steels, while others are much less so as they are empirical correlations of test data available at the time of the standards creation. A major effort funded jointly by the US Department of Transportation and PRCI has produced a comprehensive update to the girth weld defect acceptance criteria. The newly proposed procedures have two options. Option 1 is given in an easy-to-use graphical format. The determination of allowable flaw size is extremely simple. Option 2 provides more flexibility and generally allows larger flaws than Option 1, at the expense of more complex computations. Option 1 also has higher fracture toughness requirements than Option 2, as it is built on the concept of plastic collapse. In comparison to some existing codes and standards, the new procedures (1) provide more consistent level of conservatism, (2) include both plastic collapse and fracture criteria, and (3) give necessary considerations to the most frequently occurring defects in modern pipeline constructions. This paper provides an overview of the technical basis of the new procedures and validation against experimental test data.

Reality Check on Girth Weld Defect Acceptance Criteria

2010 ◽  
Author(s):  
Gery Wilkowski ◽  
Do-Jun Shim ◽  
Bud Brust ◽  
Suresh Kalyanam
Keyword(s):  
Base Metal ◽  
Safety Factor ◽  
Test Data ◽  
Large Diameter ◽  
Limit Load ◽  
Failure Stress ◽  
Specimen Thickness ◽  
Tier 2 ◽  
Acceptance Criteria ◽  
Weld Defect

This paper examines the inherent conservatisms of alternative girth weld defect acceptance criteria from the 2007 API 1104 Appendix A, CSA Z662 Appendix K, and the proposed EPRG Tier 2 criteria. The API and CSA codes have the same empirical limit-load criteria, where it has previously been shown that the conservatism on the failure stress is ∼30 to 50 percent compared to pipe test data prior to applying any safety factors. In terms of flaw length, it was found that the API/CSA limit-load equation might allow a flaw of 5% of the pipe circumference, where the properly validated limit-load equation would allow a flaw of 75% of the circumference, i.e., a safety factor of 30 percent on load corresponded to a safety factor of 15 on flaw length for that example case. Similarly there are conservatisms in a proposed EPRG Tier 2 girth weld defect acceptance criterion. This proposed criterion was directly based on curved-wide-plate data to assure that toughness was sufficient to meet limit-load conditions for a curved-wide plate. However, the curved-wide plates are really an intermediate-scale test, and still require proper scaling to pipes of different diameters. The proposed Tier 2 EPRG allowable flaw length is 7T from a large database of curved-wide-plate tests with the a/t value of less than 0.5 (or a < 3mm), and the failure stress being equal to the yield strength of the base metal (also requires the weld metal overmatch the base metal strength, and the Charpy energy at the defect location have a minimum > 30 J and average > 40 J). However, the widths of those curved-wide-plate tests are typically a factor 5 to 12 times less than typical large-diameter pipes. The proper limit-load/fracture mechanics scaling solution would have the flaw length proportioned to the plate width, not the specimen thickness. Additionally, the proper limit-load solution for a pipe in bending gives a much larger tolerable flaw size at the yield stress loading than a plate or pipe under pure tension. Example calculations showed that the EPRG Tier 2 approach is conservative on the flaw lengths by approximately 9 for pure axial tension loading, and between 34 to 79 for a pipe under bending. Suggestions are presented for an improved procedure that accounts for proper limit-load solutions for pipe tests, effects of pipe diameter, effects of internal pressure, and also a much simpler approach to incorporate the material toughness than the 2007 API 1104 Appendix A Option 2 FAD-curve approach. The fracture analyses could evoke SENB, SENT testing, or have relatively simple Charpy test data to assess the transition temperatures to ensure ductile initiation will occur.

Technical Basis for Evaluation of US DOT Seamless Pressure Vessels With Defects on Threaded Neck Used for Structural Support

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Mahendra D. Rana ◽  
David Treadwell ◽  
Srikanth Ramachandran ◽  
Abani K. Khanal
Keyword(s):  
High Pressure ◽  
Test Data ◽  
Road Transport ◽  
Pressure Vessels ◽  
Department Of Transportation ◽  
The Road ◽  
Structural Support ◽  
C 23 ◽  
Technical Basis

Seamless pressure vessels (tubes) are designed per Department of Transportation (DOT) Specification 3AAX or 3 T. These tubes are used in over- the-road transport of high pressure gases. In tube trailer, these tubes are supported at ends from outside threaded necks. This paper describes the technical basis which was used in developing CGA C-23 document, which provides guideline on inspection and evaluation of tubes neck mounting surfaces. API-579/ASME FFS-1 standard and test data were used in developing the guideline for acceptance rejection criteria of the tube neck containing local thin areas and thread wear, respectively.

Technical Basis for Flaw Acceptance Criteria for Cast Austenitic Stainless Steel Piping

2017 ◽  
Author(s):  
D. J. Shim ◽  
N. G. Cofie ◽  
D. Dedhia ◽  
D. O. Harris ◽  
T. J. Griesbach ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ferrite Content ◽  
Evaluation Procedure ◽  
Acceptance Criteria ◽  
Regulatory Guidance ◽  
The Us ◽  
Asme Code ◽  
Tensile Data ◽  
Technical Basis

According to the current ASME Code Section XI, IWB-3640 and Appendix C flaw evaluation procedure, cast austenitic stainless steel (CASS) piping with ferrite content less than 20% is treated as wrought stainless steel. For CASS piping with ferrite content equal or greater than 20%, there is currently no flaw evaluation procedure in the ASME Code. In this paper, the technical basis for a proposed flaw acceptance criteria for CASS piping is presented. The procedure utilizes the current rules in ASME Code Section XI, IWB 3640/Appendix C and the existing elastic-plastic correction factors (i.e., Z-factors) for other materials in the Code. The appropriate Z-factor to use for the CASS piping is determined based on the ferrite content (using Hull’s equivalent factor). Experimentally measured fully saturated fracture toughness and tensile data of the three most common grades of CASS material in the US (CF3, CF8 and CF8M) were used to determine the flaw acceptance criteria in the proposed method. The proposed method is conservative since it utilizes the fully saturated condition of CASS materials. In addition, it is simple and consistent with current regulatory guidance on aging management of CASS piping.

The Economics of Air Traffic Control

1980 ◽  
Vol 33 (1) ◽  
pp. 23-29
Author(s):  
Angus Hislop
Keyword(s):  
Traffic Control ◽  
Air Traffic Control ◽  
Air Traffic ◽  
Air Transport ◽  
Civil Aviation ◽  
Department Of Transportation ◽  
Private Industry ◽  
The Us ◽  
The Uk

This paper is based mainly on a study carried out in 1976/7 for the UK Department of Industry into the long-term development of air traffic control systems in Europe by a team drawn from the Civil Aviation Authority, the Royal Signals and Radar Establishment and private industry, in which Coopers and Lybrand provided the economic expertise.Until the early 1970s, air traffic control was almost completely neglected by air transport economists. Economists contributed to the planning of airports and airline operations but not to the third facet of the air transport system. However, in 1970–1, in conjunction with a programme of expansion and improvement of the country's airports and airways, the US Department of Transportation launched a major study of the airport and airways system. This was designed to establish an equitable charging policy between the different categories of user but in the event its recommendations in this area have only recently begun to be followed.

Developing Weld Defect Acceptance Criteria for a Swaged Pipe-in-Pipe System

2018 ◽  
Author(s):  
D. Zhou ◽  
T. Sriskandarajah ◽  
M. Bamane ◽  
P. Tews ◽  
S. Dugat
Keyword(s):  
Acceptance Criteria ◽  
Pipe System ◽  
Weld Defect

Further Improvements to ASME Section XI Code Case N-806 for Evaluation of Metal Loss in Class 2 and 3 Metallic Piping Buried in a Back-Filled Trench

2015 ◽  
Author(s):  
Robert O. McGill ◽  
Mark A. Moenssens ◽  
George A. Antaki ◽  
Douglas A. Scarth
Keyword(s):  
Corrosion Rate ◽  
Ease Of Use ◽  
Nuclear Industry ◽  
Task Group ◽  
Metal Loss ◽  
Buried Pipe ◽  
Acceptance Criteria ◽  
Evaluation Procedures ◽  
Technical Basis

ASME Section XI Code Case N-806, for evaluation of metal loss in Class 2 and 3 metallic piping buried in a back-filled trench, was first published in 2012. This Code Case has been prepared by the ASME Section XI Task Group on Evaluation Procedures for Degraded Buried Pipe. The Code Case addresses the nuclear industry need for evaluation procedures and acceptance criteria for the disposition of metal loss that is discovered during the inspection of metallic piping buried in a back-filled trench. A number of additional improvements have been proposed for Code Case N-806. These include expanded guidance for the determination and validation of a corrosion rate and other clarifications to improve ease of use. This paper presents an update of details of the proposed revisions to Code Case N-806 and their technical basis.

Pressure Correction Factor for Strain Capacity Predictions Based on Curved Wide Plate Testing

2012 ◽  
Author(s):  
Matthias Verstraete ◽  
Wim De Waele ◽  
Rudi Denys ◽  
Stijn Hertelé
Keyword(s):  
Correction Factor ◽  
Large Scale ◽  
Strain Capacity ◽  
Defect Assessment ◽  
Ductile Crack Growth ◽  
Large Scale Testing ◽  
Weld Defect ◽  
Girth Welds ◽  
Assessment Procedures ◽  
Tensile Strain Capacity

Strain-based girth weld defect assessment procedures are essentially based on large scale testing. Ever since the 1980’s curved wide plate testing has been widely applied to determine the tensile strain capacity of flawed girth welds. However, the effect of internal pressure is not captured in curved wide plate testing. Accordingly, unconservative predictions of strain capacity occur when straightforwardly transferred to pressurized pipes. To address this anomaly, this paper presents results of finite element simulations incorporating ductile crack growth. Simulations on homogeneous and girth welded specimens indicate that a correction factor of 0.5 allows to conservatively predict the strain capacity of a pressurized pipe through wide plate testing under the considered conditions.

The Applicability of the ASME Boiler and Pressure Vessel Code, Section XII, Transport Tanks, for Use in U.S. Federal Maritime Regulations

2010 ◽  
Author(s):  
Allen Selz ◽  
Daniel R. Sharp
Keyword(s):  
Pressure Vessel ◽  
Road Transport ◽  
Pressure Vessels ◽  
Department Of Transportation ◽  
The Road ◽  
Dangerous Goods ◽  
Division 1 ◽  
The Us ◽  
Section Viii ◽  
Marine Applications

Developed at the request of the US Department of Transportation, Section XII-Transport Tanks, of the ASME Boiler and Pressure Vessel Code addresses rules for the construction and continued service of pressure vessels for the transportation of dangerous goods by road, air, rail, or water. The standard is intended to replace most of the vessel design rules and be referenced in the federal hazardous material regulations, Title 49 of the Code of Federal Regulations (CFR). While the majority of the current rules focus on over-the-road transport, there are rules for portable tanks which can be used in marine applications for the transport of liquefied gases, and for ton tanks used for rail and barge shipping of chlorine and other compressed gases. Rules for non-cryogenic portable tanks are currently provided in Section VIII, Division 2, but will be moved into Section XII. These portable tank requirements should also replace the existing references to the outmoded 1989 edition of ASME Section VIII, Division 1 cited in Title 46 of the CFR. Paper published with permission.

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