Full-Scale Step-Load-Hold Tests on X65 and X70 Line Pipe Steels

2020 ◽  
Author(s):  
Andrew Cosham ◽  
Brian N. Leis ◽  
Mures Zarèa ◽  
Fabian Orth ◽  
Valerie Linton
Keyword(s):  
Impact Energy ◽  
Full Scale ◽  
Small Scale ◽  
Battelle Memorial Institute ◽  
Pipe Steels ◽  
Line Pipe ◽  
Delayed Failure ◽  
Hold Period ◽  
Full Scale Tests ◽  
Scale Step

Abstract A time-delayed failure due to stress-activated creep (cold-creep) will occur if the applied load is held constant at a level above the threshold. The results of small and full-scale tests on line pipe steels conducted by the Battelle Memorial Institute and the British Gas Corporation in the 1960s and 70s indicated that the (empirical) threshold for a time-delayed failure was approximately 85–95% SAPF (straight-away-pressure-to-failure). The line pipe steels were Grades X52 or X60, and the full-size equivalent Charpy V-notch impact energy (where reported) did not exceed 35 J. The strength and toughness of line pipe steels has significantly increased over the decades due to developments in steel-making and processing. The question then is whether an empirical threshold based on tests on lower strength and lower toughness steels is applicable to higher strength and higher toughness steels. A Tripartite Project was established to answer this question. The Australian Pipelines and Gas Association (APGA), the European Pipeline Research Group (EPRG) and the Pipeline Research Council International (PRCI) collaborated in conducting six full-scale step-load-hold tests on higher strength and higher toughness steels. Companion papers present the other aspects of this multi-year project. The line pipe supplied for testing is summarised below. • Identifier — Dimensions and Grade — f.s.e. Charpy V-notch impact energy at 0 C • APGA [A] — 457.0 × 9.1 mm, Grade X70M, ERW — 263 J • EPRG [E] — 1016.0 × 13.6 mm, Grade X70M, SAWL — 165 J • PRCI [P] — 609.6 × 6.4 mm, Grade X65, SAWL — 160 J Six step-load-hold tests, each with four part-through-wall defects, were conducted. Test Nos. APGA 1 and 2, and Nos. EPRG 1 and 2 were conducted at Engie, France. Test Nos. PRCI 1 and 2 were conducted at EWI, USA. The full-scale tests, and associated small-scale testing, are described and discussed. A time-delayed failure due to stress-activated creep occurred in each of the step-load-hold tests. The failures occurred during a hold-period at 93.7–104.4% SAPF, after a hold of approximately 1.0–13.9 hours. The results of the six step-load-hold tests are consistent with a threshold for a time-delayed failure of approximately 90% SAPF.

A Pressure Reduction to Prevent a Time-Delayed Failure in a Damaged Pipeline

2020 ◽  
Author(s):  
Andrew Cosham ◽  
Brian N. Leis ◽  
Paul Roovers ◽  
Mures Zarèa ◽  
Valerie Linton
Keyword(s):  
Full Scale ◽  
The Other ◽  
Battelle Memorial Institute ◽  
Pressure Reduction ◽  
Pipe Steels ◽  
Percent Reduction ◽  
Lower Strength ◽  
Line Pipe ◽  
Delayed Failure ◽  
Strength And Toughness

Abstract A time-delayed failure due to stress-activated creep (cold-creep) is a failure that occurs under a constant load and with no growth due corrosion, fatigue or some other environmentally assisted time-dependent degradation mechanism. A time-delayed failure is prevented by reducing the pressure. ASME B31.4 and B31.8 recommend a 20 percent reduction, to 80 percent of the pressure at the time of damage or discovery. T/PM/P/11 Management Procedure for Inspection, assessment and repair of damaged (non-leaking) steel pipelines, an internal procedure used by National Grid, specifies a 15 percent reduction. The guidance in ASME B31.4 and B31.8, and in T/PM/P/11, is directly or indirectly based on the results of tests on the long term stability of defects conducted by the Battelle Memorial Institute and British Gas Corporation in the 1960s and 70s. The line pipe steels were Grades X52 or X60, and the full-size equivalent Charpy V-notch impact energy (where reported) did not exceed 35 J. The tests indicated that the threshold for a time-delayed failure was approximately 85–95% SAPF (straightaway-pressure-to-failure). The strength and toughness of line pipe steels has significantly increased over the decades due to developments in steel-making and processing. The question then is whether an empirical threshold based on tests on lower strength and lower toughness steels is applicable to higher strength and higher toughness steels. In the Tripartite Project, the Australian Pipelines and Gas Association (APGA), the European Pipeline Research Group (EPRG) and the Pipeline Research Council International (PRCI) collaborated in conducting full-scale six step-load-hold tests on higher strength and higher toughness steels. Companion papers present the other aspects of this multi-year project. An empirical threshold for a time-delayed failure is estimated using the results of the six step-load-hold tests. That estimate is also informed by the other published small and full-scale tests (on lower strength and lower toughness steels). The Ductile Flaw Growth Model is used to infer the effect of strength and toughness on the threshold for a time-delayed failure. A 15 percent pressure reduction, to 85 percent of the pressure at the time of damage (or of the maximum pressure that has occurred since the time of damage), is considered to be sufficient to prevent a time-delayed failure due to stress-activated creep in lower and higher toughness, in lower and higher strength, and in older and newer line pipe steels.

TurkStream Collapse Test Program

2018 ◽  
Author(s):  
Chris Timms ◽  
Doug Swanek ◽  
Duane DeGeer ◽  
Arjen Meijer ◽  
Ping Liu ◽  
...  
Keyword(s):  
Thermal Ageing ◽  
Full Scale ◽  
The Black Sea ◽  
Small Scale ◽  
Test Program ◽  
Line Pipe ◽  
Medium Scale ◽  
Collapse Resistance ◽  
Full Scale Tests ◽  
The Impact

The TurkStream pipeline project is designed to transport approximately 32 billion cubic meters of natural gas annually from Russia to Turkey under the Black Sea, with more than 85% of the deep-water route being deeper than 2000 m. The offshore section is intended to consist of two parallel lines, each approximately 900 km long. The preliminary stages of the front end engineering design (pre-FEED) phase was managed by INTECSEA. To support the analyses and design of the deepest portions, a full scale collapse test program was performed by C-FER Technologies (C-FER). This collapse test program, which included 62 full-scale collapse and pressure+bend tests, 54 medium-scale ring collapse tests, and hundreds of small-scale tests, was primarily aimed at measuring, quantifying and documenting the increase in pipe strength and collapse resistance resulting from the thermal induction heat treatment effect (thermal ageing) that arises during the pipe coating process. Two grades of 32-inch (813 mm) outside diameter (OD) line-pipe, SAWL450 and SAWL485 with wall thicknesses of 39.0 mm or 37.4 mm, respectively, were supplied from various mills for testing. The collapse test program objectives were as follows: • Determine the collapse resistance of line pipes originating from various pipe mills; • Determine the pressure+bend performance of line pipes originating from various pipe mills; • Measure the effect of thermal ageing on material and collapse testing results, including the impact of multiple thermal cycles; and • Evaluate the results of medium-scale ring collapse tests as compared to full-scale tests. This paper presents selected results of this work, along with some comparisons to predictive equations.

The Misconception of Employing CVN Toughness as Key-Measure in Ductile Crack Arrest Prediction for Modern Line-Pipe Steels

2014 ◽  
Author(s):  
Alexander Völling ◽  
Christoph Kalwa ◽  
Marion Erdelen-Peppler
Keyword(s):  
Ductile Fracture ◽  
Data Base ◽  
Model Calibration ◽  
Crack Arrest ◽  
Full Scale ◽  
Small Scale ◽  
Material Strength ◽  
Original Material ◽  
Pipe Steels ◽  
Line Pipe

Since the late 1960s’ the Battelle Two-curve (BTC) model is the standard method applied in setting up design requirements with regard to the prevention of long-running ductile fracture in pipelines. It is a straightforward tool employing Charpy-V notch (CVN) toughness as key-measure for material resistance against crack propagation. On basis of pipe dimensions, material strength, and under consideration of decompression behavior of the transferred media, it enables to set up requirements for a minimum CVN toughness level to achieve crack arrest. Overall applicability of the BTC model is based on calibration of the underlying equations to a sound data-base, including both full-scale burst test results and small-scale laboratory testing data involving typical line-pipe grades at that period, i.e. up to grade X70 steels with below 100 J upper-shelf CVN toughness. Now over the last decades, mechanical behavior of line-pipe steels was improved significantly. Responding to market demands, higher grades were designed and also toughness levels were raised as outcome of R&D efforts within the steel industry. Unfortunately, stepping outside the original material data-base from BTC model calibration, this method did forfeit its reliability. At the beginning, mispredictions were mainly related to higher grade steels and elevated operating pressures. But more recent full-scale tests did reveal discrepancies in application of the BTC model also for so-called new vintage steels, i.e. grades actually being inside the original data base for model calibration but from current production routes. With regard to applicability/reliability of BTC model based predictions for crack arrest, the origin of uncertainty has particularly been traced back to the involved material toughness measure. Nowadays, it is common sense that the CVN upper-shelf toughness value inadequately describes the resistance against running ductile fracture. More recent thoughts coherently argue towards closer involving stress-strain response and plastic deformation capacities of the material. On basis of results for grades X65, X80 and X100, the general relation between ductility and toughness is discussed. Finally, an elastic-plastic fracture mechanics related analytical approach is introduced which enables to quantify the resistance against ductile fracture propagation. The objective is to provide a reliable procedure for crack arrest prediction in line-pipe steels.

Development of Fatigue Design Data for the Ormen Lange Offshore Project: An Overview

2006 ◽  
Author(s):  
Hans Olav Knagenhjelm ◽  
Oddvin O̸rjasæter ◽  
Per J. Haagensen
Keyword(s):  
Crack Growth ◽  
Full Scale ◽  
Small Scale ◽  
Formation Water ◽  
Worst Case ◽  
Vortex Induced Vibrations ◽  
Welding Defects ◽  
Condensed Water ◽  
Full Scale Tests ◽  
Full Scale Testing

The Ormen Lange offshore pipelines from shore to the field go through very difficult terrain creating freespans in the range 40–80m for the 30” lines. For the 6” lines long freespans will be present prior to burial and vortex induced vibrations (VIV) will give a contribution during laying due to strong currents. Using existing codes for fatigue calculation was giving too conservative results compared to the welding technology used and experience from SCR work showed that better S-N data should be expected. A dedicated program was started as part of the Ormen Lange (OL) technology verification program overseen by Norwegian Authorities. An overview of the results is presented here. A full evaluation of the data is not yet complete. Papers will be published later presenting the full technical details and dataprocessing. Fatigue test results from the OL pipeline fatigue verification are presented focusing on the following topics: • Defect sizes in pipeline production welds; • Contractor-A: 5G welding position; • Contractor-B: 2G welding position; • 6” pipe full scale testing; • 30” pipe full scale testing; • Residual stresses; • Crack growth tests and sector specimen fatigue tests in production environments. The following are a summary of the main test variables in the program: • Mapping of actual welding defects compared to AUT results. • Welds with varying misalignment (high/low) and lack of penetration (LOP) from installation contractors tested in air. • Welds with natural welding defects in internal environment (Condensed water and formation water). • Welds with notches made by electrical discharge machining (EDM) (2×65mm and 2×15mm) in internal environment (condensed water and formation water). • Crack growth tests using large compact tension (CT) specimens in air, seawater and internal product environments (condensed water and formation water). • Full scale tests including worst case high/low, LOPs, and tests with normal welds including repair welds. The following main conclusions can be drawn from the work: • Small scale testing with representative worst case defects predicts well large scale testing results with the same features when the small scale specimen stresses are corrected for bending moments etc. arising from the cutout of the pipe. • Full scale testing of 30”×35.5mm wall thickness 2G pipes welded continuously (without start/stop) with worst case defects and high/low exceeds the D curve. • Full-scale tests of 30”×35.5mm wall thickness 5G non continuous welds with worst case defects and high/low exceeds the E curve. • Pipe welds showed low or even compressive residual stresses in the root. For continuously welded pipes the stress levels were low but more varying, also on the cap side. This partly explains the good results. • It is verified that the fatigue loads during operation are below the threshold of crack growth, and thus fatigue will not be a probable failure mechanism. This is under the condition that the measurements of vortex induced vibrations (VIV) during operation confirm the engineering calculations.

Full-Scale Reeling Tests of HFI Welded Line Pipe for Offshore Reel-Laying Installation

2014 ◽  
Author(s):  
Karl Christoph Meiwes ◽  
Susanne Höhler ◽  
Marion Erdelen-Peppler ◽  
Holger Brauer
Keyword(s):  
Mechanical Testing ◽  
Mechanical Test ◽  
Strength Properties ◽  
Full Scale ◽  
Bending Test ◽  
Small Scale ◽  
Pipe Material ◽  
Deformation Capacity ◽  
Line Pipe ◽  
Tension And Compression

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.

Effects of Soil Cohesiveness and Depth on Dynamic Ductile Fracture Speeds

2008 ◽  
Author(s):  
D. Rudland ◽  
D.-J. Shim ◽  
G. M. Wilkowski ◽  
S. Kawaguchi ◽  
N. Hagiwara ◽  
...  
Keyword(s):  
Ductile Fracture ◽  
Large Scale ◽  
Soil Depth ◽  
Crack Arrest ◽  
Small Scale ◽  
Total Density ◽  
Pipe Material ◽  
Pipe Steels ◽  
Line Pipe ◽  
Fracture Arrest

The ductile fracture resistance of newer line pipe steels is of concern for high grade/strength steels and higher-pressure pipeline designs. Although there have been several attempts to make improved ductile fracture arrest models, the model that is still used most frequently is the Battelle Two-Curve Method (TCM). This analysis incorporates the gas-decompression behavior with the fracture toughness of the pipe material to predict the minimum Charpy energy required for crack arrest. For this analysis, the influence of the backfill is lumped into one empirically developed “soil” coefficient which is not specific to soil type, density or strength. No attempt has been made to quantify the effects of soil depth, type, total density or strength on the fracture speeds of propagating cracks in line pipe steels. In this paper, results from small-scale and large-scale burst tests with well-controlled backfill conditions are presented and analyzed to determine the effects of soil depth and cohesiveness on the fracture speeds. Combining this data with the past full-scale burst data used in generating the original backfill coefficient provides additional insight into the effects of the soil properties on the fracture speeds and the arrest of running ductile fractures in line pipe materials.

scholarly journals Some Aspects of the Comparison of Model and Full Scale Tests

1925 ◽  
Vol 29 (175) ◽  
pp. 299-332
Author(s):  
D. W. Taylor
Keyword(s):  
United States ◽  
Advisory Committee ◽  
Human Life ◽  
The United States ◽  
Full Scale ◽  
Large Field ◽  
Small Scale ◽  
Free Flight ◽  
Flight Tests ◽  
Full Scale Tests

Aeronautics now covers a large field. The bibliography alone, compiled and published annually by the United States National Advisory Committee for Aeronautics, requires something like two hundred pages of a book seven inches by ten inches. Needless to say, I am not undertaking to review the whole field.Owing to the difficulties of conducting free flight tests of performance and the fact that we cannot afford to make many mistakes in an appliance whose operation involves the risk of human life, it is peculiarly desirable that we may be able to predict the performance of the completed airplane from small-scale experiments; and probably in no other branch of mechanical science have we at present so many research laboratories.

Performance Evaluation of High Quality HFW Linepipe by a Series of Full-Scale Pipe Tests

2014 ◽  
Author(s):  
Satoshi Igi ◽  
Teruki Sadasue ◽  
Kenji Oi ◽  
Satoru Yabumoto ◽  
Shunsuke Toyoda
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Internal Pressure ◽  
Fatigue Test ◽  
Full Scale ◽  
Safety Performance ◽  
Small Scale ◽  
High Quality ◽  
Burst Test ◽  
Full Scale Tests

Newly-developed high quality high frequency electric resistance welded (HFW) linepipes have recently been used in pipelines in reel-lay applications and low temperature service environments because of their excellent low temperature weld toughness and cost effectiveness. In order to clarify the safety performance of these HFW linepipes, a series of full-scale tests including a hydrostatic burst test at low temperature, fatigue test and tension test under high internal pressure was conducted, together with small-scale tests such as impact energy and standard fracture toughness tests, which are generally used in mill production and pre-qualification tests. The Charpy transition curve of the developed HFW pipe occurred at a temperature much lower than −45°C. Based on the low-temperature hydrostatic burst test with a notched weld seam at −45°C, the weld of the HFW linepipe presented the same level of leak-before-break (LBB) behavior, as observed in UOE pipes. A full-pipe fatigue test of HFW pipes with repeated internal pressurizing was conducted. The fatigue strength of the developed HFW linepipe shows better performance than butt weld joints because of the smoothness at its weld portion, which is achieved by mechanical grinding of the weld reinforcement. Full-scale pipe tensile tests of girth welded joints were performed with an artificial surface notch at the heat affected zone in the girth weld. The influence of internal pressure was clearly observed in these tests. Based on the above-mentioned full-scale tests, the safety performance of high quality HFW linepipe is discussed in comparison with the mechanical properties in the small-scale tests such as the Charpy and standard fracture toughness tests, especially when the notch was placed in the welded seam.

How New Vintage Line-Pipe Steel Fracture Properties Differ From Old Vintage Line-Pipe Steels

2012 ◽  
Author(s):  
G. Wilkowski ◽  
D.-J. Shim ◽  
Y. Hioe ◽  
S. Kalyanam ◽  
F. Brust
Keyword(s):  
Brittle Fracture ◽  
Fracture Behavior ◽  
Pipe Steel ◽  
Full Scale ◽  
Actual Behavior ◽  
Correction Factors ◽  
Pipe Steels ◽  
Line Pipe ◽  
Line Pipe Steel ◽  
Fracture Control

Newer vintage line-pipe steels, even for lower grades (i.e., X60 to X70) have much different fracture behavior than older line-pipe steels. These differences significantly affect the fracture control aspects for both brittle fracture and ductile fracture of new pipelines. Perhaps one of the most significant effects is with brittle fracture control for new line-pipe steels. From past work brittle fracture control was achieved through the specification of the drop-weight-tear test (DWTT) in API 5L3. With the very high Charpy energy materials that are being made today, brittle fracture will not easily initiate from the pressed notch of the standard DWTT specimen, whereas for older line-pipe steels that was the normal behavior. This behavior is now referred to as “Abnormal Fracture Appearance” (AFA). More recent work shows a more disturbing trend that one can get 100-percent shear area in the standard pressed-notch DWTT specimen, but the material is really susceptible to brittle fracture. This is a related phenomenon due to the high fracture initiation energy in the standard DWTT specimen that we call “Abnormal Fracture Behavior” (AFB). This paper discusses modified DWTT procedures and some full-scale results. The differences in the actual behavior versus the standard DWTT can be significant. Modifications to the API 5L3 test procedure are needed. The second aspect deals with empirical fracture control for unstable ductile fractures based on older line-pipe steel tests initially from tests 30-years ago. As higher-grade line-pipe steels have been developed, a few additional full-scale burst tests have shown that correction factors on the Charpy energy values are needed as the grade increases. Those correction factors from the newer burst tests were subsequently found to be related to relationship of the Charpy energy values to the DWTT energy values, where the DWTT has better similitude than the Charpy test for fracture behavior (other than the transition temperature issue noted above). Once on the upper-shelf, recent data suggest that what was once thought to be a grade correction factor may really be due to steel manufacturing process changes with time that affect even new low-grade steels. Correction factors comparable to that for X100 steels have been indicated to be needed for even X65 grade steels. Hence the past empirical equations in Codes and Standards like B31.8 will significantly under-predict the actual values needed for most new line-pipe steels.

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