Burst Pressure Prediction of Pipes With SCC Colonies: Evaluation of Intelligent Flaw Interaction Rules Using Full-Scale Burst Tests

Author(s):  
Bo Wang ◽  
Banglin Liu ◽  
Yong-Yi Wang ◽  
Alex Wang ◽  
Steve Rapp

Abstract This is the second paper in a two-paper series which covers the PRCI-funded work aimed at the development of intelligent flaw interaction rules (termed PRCI-CRES SIA-1-5 rules). The first paper focused on the development of the rules using numerical analyses. This paper covers the evaluation of the rules through full-scale burst tests and accompanying small-scale material tests. Four full-scale burst tests were conducted on 20” and 18” OD pipe segments with SCC. The SCC colonies on the test sections were inspected using MPI, PAUT, ECA, and IWEX. The small-scale material tests were conducted to measure pipe tensile strength and Charpy impact energy. The four test sections were pressurized until burst. The burst tests were recorded using multiple video cameras to capture the global behavior and detailed crack opening process at the burst locations. With the videos and the post-test examination of the failure surfaces, the full-scale burst tests provide not only the burst pressure but also information for the validation of the fundamental principles of the new interaction rules. The modified Ln-sec method was used to predict the burst pressure using the equivalent crack size from different flaw interaction rules and the measured pipe material properties. The PRCI-CRES SIA-1-5 rules were found to provide the most accurate and precise burst pressure prediction when factors other than flaw interaction rules remain the same. The application of the PRCI-CRES SIA-1-5 rules can reduce unnecessary hydrotests and/or other remediation actions with accurate, not overly conservative, burst pressure prediction.

Author(s):  
Karl Christoph Meiwes ◽  
Susanne Höhler ◽  
Marion Erdelen-Peppler ◽  
Holger Brauer

During reel-laying repeated plastic strains are introduced into a pipeline which may affect strength properties and deformation capacity of the line pipe material. Conventionally the effect on the material is simulated by small-scale reeling simulation tests. For these, coupons are extracted from pipes that are loaded in tension and compression and thermally aged, if required. Afterwards, specimens for mechanical testing are machined from these coupons and tested according to the corresponding standards. Today customers often demand additional full-scale reeling simulation tests to assure that the structural pipe behavior meets the strain demands as well. Realistic deformations have to be introduced into a full-size pipe, followed by aging, sampling and mechanical testing comparable to small-scale reeling. In this report the fitness for use of a four-point-bending test rig for full-scale reeling simulation tests is demonstrated. Two high-frequency-induction (HFI) welded pipes of grade X65M (OD = 323.9 mm, WT = 15.9 mm) from Salzgitter Mannesmann Line Pipe GmbH (MLP) are bent with alternate loading. To investigate the influences of thermal aging from polymer-coating process one test pipe had been heat treated beforehand, in the same manner as if being PE-coated. After the tests mechanical test samples were machined out of the plastically strained pipes. A comparison of results from mechanical testing of material exposed to small- and full-scale reeling simulation is given. The results allow an evaluation of the pipe behavior as regards reeling ability and plastic deformation capacity.


Author(s):  
Satoru Takano ◽  
Masao Ono ◽  
Sotaro Masanobu

For a fundamental understanding of pipe wear under hydraulic transportation of deep-sea mining, a small scale test is conducted because there are many restrictions in conducting a full scale test. The small scale test apparatus are set up using the pipes of about 80mm in diameter and the rocks of which maximum particle diameters are about 20mm are used. In the test, the pipe materials and the pipe inclination are changed to evaluate the differential of the amount of pipe material loss. Furthermore, the amount of the pipe material loss in full scale is estimated based on the small scale test results.


Author(s):  
Doug P. Fairchild ◽  
Svetlana Shafrova ◽  
Huang Tang ◽  
Justin M. Crapps ◽  
Wentao Cheng

There are generally two reasons for conducting full-scale tests (FSTs) for the measurement of pipe or weld strain capacity, (1) to generate data useful in verifying the accuracy of a strain capacity prediction model, or (2) to test materials being considered for use. The former case involves exploring variables important to the scope of the model, while the latter involves project specific materials and girth weld procedures often combined with upper bound cases of weld misalignment. Because the challenge of strain-based design is relatively new, FSTs should be used for both reasons cited above. This paper provides observations, lessons learned, and recommendations regarding full-scale pipe strain capacity tests. This information has been developed through the conduct, witness, or review of 159 FSTs. One of the most important aspects of full-scale testing is the preparation of welded pipe test specimens. It is imperative that the specimens be fabricated with materials of known properties and that all possible measures be taken to limit variations from the intended specimen design. It has been observed that unexpected results are often due to irregularities in pipe material strength, weld strength, weld toughness, or the presence of unintended weld defects in a specimen designed to contain just man-made defects. Post-test fractography and metallurgical examination are very useful in explaining the performance of a FST; therefore, failure analysis is discussed.


Author(s):  
Israel Marines-Garcia ◽  
Jorge A. Aldana-Díaz ◽  
Philippe P. Darcis ◽  
Hector M. Quintanilla

Offshore pipelines projects, installed by reel-laying operations, are gaining momentum due to the increasing worldwide capacity of Reel Lay Vessels. It is well known that reel-laying installation causes repeated plastic straining (cyclic deformation) and, as a consequence, cyclic strain and ageing test is usually required for qualifying line pipe materials for such installation method. This qualification is typically named reeling simulation. Reeling simulations can be made via full or small scale. In practice, full scale qualification lead time and full scale reeling simulation machines availability could be a constraint, thus, small scale reeling simulation is usually the best alternative. However, the similitude of small scale versus full scale simulations could be questioned. On this basis, an extensive study was carried-out considering tensile, toughness and sour testing, in order to evaluate the material response after reeling simulation, in order to clarify if the line pipe material will behave similarly regardless the straining method (small scale or full scale). Different small scale samples configuration for straining were tested, depending on the posterior mechanical or sour test, and two different full scale reeling simulation machines were used for plain pipes straining. Five seamless plain pipes, X65 line pipe were used for this study, with 3 (three) different outer diameters of 10.75″, 11.67″ & 16″ (273 mm, 296 mm & 406 mm). The current paper will present the main mechanical results of these materials after strain and ageing condition, comparing full and small scale straining methods.


1974 ◽  
Vol 96 (4) ◽  
pp. 330-334 ◽  
Author(s):  
R. J. Podlasek ◽  
R. J. Eiber

This paper describes the use of the crack opening displacement (COD) test to predict the fracture initiation transition temperature of high toughness, low-transition temperature in line pipe. A series of COD tests using t × t and t × 2t specimens made from this line pipe material. The COD test was conducted over a range of temperatures and the point where the upper shelf COD values began to decrease with decreasing temperature was defined. To verify the full-scale significance of this temperature, a series of three experiments was conducted on 48-in. (1.22m) dia line pipe to bracket the transition temperature defined in the COD Test. The results suggest that the COD transition temperature can ve used to define the fracture initiation temperature for static loading in pipe. In addition, in the transition temperature region, the full-scale results, while limited in number, suggest that the COD values could possibly be used to predict the critical flaw sizes in the pipe material.


Author(s):  
Lee Fredette ◽  
F. W. Brust

The USNRC is anticipating updating their leak-before-break (LBB) procedures. One of the technical areas of concern in the existing procedures is the prediction of the crack-opening-displacements (COD) needed for estimating the postulated leakage crack size for a prescribed leakage detection capability. If cracks develop in the welded area of a pipe, as is often the case, residual stresses in the weld may cause the crack to be forced closed. Earlier studies have shown that pipe welding produces high residual stresses with a sharp stress gradient ranging from tension to compression through the thickness of the welded area of the pipe. The current guidelines are inadequate to predict crack size based on leak rates for cracks in welded areas of pipes. The current guidelines rely on the calculation of the crack-opening-displacement as related to pipe loading. Values from the current guidelines are used to predict a crack’s cross sectional area and, in turn, to determine the severity of an existing crack by monitoring in-service leakage rates. The equations currently in use are applicable to service loaded pipe material only. Residual stresses caused by cold work, welding, etc. are neglected. This study uses two and three dimensional finite element models and weld residual stress calculation software created at Battelle Memorial Institute to develop correction factors to be used with the traditional design equations. The correction factors will compensate for the effects of welding induced residual stresses on cracks in pipe welds. This study concentrates on type 316 stainless steel material properties, but the COD corrections should be equally applicable to all stainless steels, and also can be used for ferritic steels. A test matrix of pipe radius, thickness, and crack size was used to develop the equation correction factors. Pipe wall thicknesses (t) of 7.5 mm (0.295 in.), 15 mm (0.590 in.), 22.5 mm (0.886 in.), and 30 mm (1.181 in.) were studied in pipes with mean radius to thickness ratios of 5, 10, and 20. Cracks with half-lengths in radians of π/16, π/8, π/4, and π/2 were introduced in these virtual pipes. The matrix of results was used to produce correction factors for crack opening displacement equations applicable to a broad range of pipe sizes.


Author(s):  
Niels Kerstens ◽  
Ping Liu ◽  
Duane DeGeer

Comprising 4 pipelines over 900 km in length, with 32-in diameter and traversing water depths over 2200 m, the South Stream project requires a step-out in technology application. Following several years of preparation, the project is now approaching its implementation. In order to document the reliability of the collapse resistance for South Stream, an extensive material development program was initiated and executed, including small scale, medium scale, and full scale testing on over one hundred purposely manufactured pipe joints by world’s 5 leading mills. Testing performed included plate tests, full scale collapse tests on various combinations of plate sources, steel grades, and thermal ageing condition, pressure-bend tests, and reverse bending tests. A large number of medium and small scale tests were performed to allow the development of a suitably reliable statistical database for the probabilistic wall thickness design. In addition, programs were developed and executed for weldability tests, performing over one hundred trial welds, and for H2S resistance tests. This material development program was built on INTECSEA’s extensive experience with deep water large diameter pipelines (i.e. Oman-India, Blue Stream, Medgaz, Mardi Gras, IGI, etc.). Due to its extent and rigorous approach the South Stream material development program was able to conclusively prove the feasibility of the selected technological approach at an industrial scale. This paper provides an overview of the key design issues that were successfully addressed and the major technological advances that have been implemented as part of the linepipe material development process for deepwater pipelines in an H2S containing environment. The practical significance of this program is to optimize the wall thickness to a level that is manufacturable by the industry and hence enables the South Stream Project to proceed with its unprecedented depth and diameter combination.


Author(s):  
Robert M. Andrews ◽  
Neil A. Millwood ◽  
A. David Batte ◽  
Barbara J. Lowesmith

The drive to reduce the installed cost of high-capacity long-distance pipelines has focused attention on increasing the strength of the pipe material, in order to reduce the tonnage of material purchased, transportation and welding costs. In parallel with developments in plate rolling and pipe fabrication, the properties and performance of prototype pipe materials and construction welds have already been extensively evaluated. While these studies have provided considerable confidence in the performance of X100 pipe, a major remaining issue in the introduction of such steels has been an understanding of the resistance to propagating fractures. The scarcity of relevant fracture propagation data and concerns about the measurement and specification of toughness in high strength steel pipes have led to doubts that the existing methods for control of ductile fracture can be extrapolated to X100 strength levels. In order to provide experimental data on which to base fracture control approaches, a Joint Industry Project has been undertaken using conditions representative of potential applications. Results are presented from two full-scale fracture propagation tests on 914mm pre-production grade X100 pipes pressurised using natural gas. The full-scale results are compared with small-scale test specimen data and also with results from other full-scale tests on high strength steel pipes. This provides a valuable insight into the fracture response of these materials. Information has also been obtained concerning the predictive capability of current gas decompression models. These results provide a contribution to the development of fracture control plans in pipelines using X100 steel linepipe.


Author(s):  
M. C. Muth ◽  
A. M. Beltran

Water-cooled high temperature gas turbine technology has been under investigation by the Gas Turbine Division of the General Electric Company for the past 15 years. The transition from testing small scale laboratory-size hardware to full-scale gas turbine components was initiated in 1975 by General Electric and extended further under the U.S. Department of Energy’s High Temperature Turbine Technology (HTTT) Program. A key element in this transition was the identification of a composite (hybrid) design for the first-stage nozzles. This design permits efficient heat transfer to the water-cooling passage-ways, thus lowering effective strains and increasing part life. The results of GE’s extensive efforts over many years to develop a composite water-cooled first-stage nozzle were further confirmed through the successful fabrication and testing of full-scale hardware under the DOE/HTTT Program. This paper describes the post test metallurgical evaluation of two segments of the nozzle tested under the DOE/HTTT program. A brief description of the actual hot-gas path testing of the part is given. The bulk of the paper deals with a microstructural evaluation of the segments including microprobe traces and hardness surveys. Pre- and post-test non-destructive evaluations are also reviewed.


Author(s):  
D.M. Seyedi ◽  
C. Plúa ◽  
M. Vitel ◽  
G. Armand ◽  
J. Rutqvist ◽  
...  

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