Investigations into the Fatigue Strength of CRA Lined Pipe

Johnston, Carol; Nageswaran, Channa; London, Tyler

doi:10.4043/27141-ms

Cited by 5 publications

(5 citation statements)

References 6 publications

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“…Furthermore, fatigue life of the alloy 625 liner is higher than that of the alloy 316L liner. This is in line with other studies, where it has been shown that crack initiation and growth is slower in alloy 625 than in alloy 316L [22].…”

Section: Resultssupporting

confidence: 93%

“…Eighteen dumbbell specimens, six for each pipe size, are fatigue tested at a frequency of 2 Hz to determine the fatigue endurance of MLPs with imperfect liners. Although the maximum service temperature can be high (100-150 • C or above), testing is conveniently undertaken at room temperature as fatigue cracks generally grow slower at elevated temperature [22].…”

Section: Small Scale Fatigue Testsmentioning

confidence: 99%

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Low Cycle Fatigue of Subsea Mechanically Lined Pipeline With Liner Imperfections

Pépin

Tkaczyk

O’Dowd

et al. 2017

Volume 4: Materials Technology

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There is an ever-increasing demand for subsea transport of corrosive constituents which requires the use of corrosion resistant pipelines. This has generated interest in mechanically lined pipe (MLP) which consists of carbon steel pipe lined with a thin layer of corrosion resistant alloy (CRA), typically stainless steel. The CRA liner is adhered to the backing pipe by means of an interference fit. MLPs have been traditionally installed subsea using low strain methods such as towing, S-lay or J-lay. More recently, the efficient reel-lay method, typically used for pipelines up to 18” (457.2 mm) in diameter, has also been considered. To prevent damage to the MLP during high strain bending (i.e. wrinkling of CRA the liner) and thus allow reel-lay installation, TechnipFMC has qualified reeling of MLPs at ambient and elevated pressures. The ambient reeling approach, where the liner thickness is increased to prevent wrinkling during reeling, is appropriate for smaller diameter MLPs. For larger pipelines, it is generally more cost-effective to pressurise the MLP during reeling. Concerns have been expressed that liner imperfections such as small dents or wrinkles, introduced during manufacturing, installation or service, may compromise the integrity of the MLP subjected to high in-service cyclic loading. Therefore, this study was undertaken to examine the criticality of such flaws and determine the low cycle fatigue endurance of reeled MLPs with imperfections. First, a numerical study was undertaken to estimate in-service stress/strain ranges in the MLPs with liner flaws. Subsequently, small scale tests were carried out to quantify the fatigue performance of such MLPs. The obtained results confirmed that there is a negligible risk of failure of MLP flowlines due to crack initiation at liner imperfections and subsequent breach of the CRA layer, even for pipelines subjected to very severe inservice cyclic loading.

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Section: Resultssupporting

confidence: 93%

Section: Small Scale Fatigue Testsmentioning

confidence: 99%

Low Cycle Fatigue of Subsea Mechanically Lined Pipeline With Liner Imperfections

Pépin

Tkaczyk

O’Dowd

et al. 2017

Volume 4: Materials Technology

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“…Weld overlay is a fusion-based welding process for depositing coats, allowing manufacturing clad pipes with various thicknesses, diameters, and lengths [8]. Besides, weld overlay is employed to seal the liner at the pipe ends and joint preparation of lined pipes [9,10]. TIG hotwire is often used for cladding critical parts of subsea equipment because it presents high efficiency, low heat input, and high quality [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Investigating an API X65 steel pipe cladded with alloy 625

Knerek¹,

Lemos²,

Voort³

et al. 2021

Tecnol. Metal. Mater. Min.

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Pipes (rigid risers and flowlines) are employed to transport oil and gas from the wells to the platforms. In these pipes, the fluids can be very corrosive and, therefore, corrosion-resistant alloys (CRA) must be chosen. Alloy 625 is a well-known CRA with improved corrosion resistance. However, nickel-based alloys have high cost compared to that of the low alloy steels, thus pipes entirely made of CRA are economically unfeasible. Internal coating with a thin CRA layer is a less expensive and suitable alternative than the solid CRA. An internal coating by overlay manufacturing process can induce phase transformations at the interface. In this work, an alloy 625 cladding layer was deposited in an API X65 steel substrate with an automatic weld overlay system using gas tungsten arc welding (GTAW) process (often referred to as tungsten inert gas (TIG) hotwire). Thus, this study aims at evaluating an API X65 steel pipe cladded with alloy 625. The results show a suitable nickel-based alloy overlay deposited in an API X65 carbon steel substrate.

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“…Reelability of MLPs has been the subject of numerous studies over the past decades [17][18][19][20][21][22][23][24][25][26]. It was shown that when an MLP is subjected to bending the liner initially ovalizes together with the backing pipe [27,28].…”

Section: Introductionmentioning

confidence: 99%

Prediction of Liner Wrinkling During High Strain Bending of Mechanically Lined Pipe

Pépin

Tkaczyk

Martínez

et al. 2019

Volume 5B: Pipelines, Risers, and Subsea Systems

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A high demand for transport of corrosive fluids subsea has generated interest in solid corrosion resistant alloy (CRA) and bi-metal pipes. Bi-metal pipes, including hot-roll bonded (HRB) clad and mechanically lined pipes (MLP), are made of a carbon steel (CS) pipe lined with a CRA layer. Mechanically lined pipes, where the CRA liner is held inside the host pipe by means of an interference fit, offer shorter lead times and are considerably more economical than equivalent solid CRA and HRB clad pipes with a metallurgical bond between CS and CRA layers. Reel-lay is a cost-effective method for installing subsea pipelines up to 18” (457.2 mm) in diameter. However, plastic straining associated with reeling may trigger wrinkling of the CRA liner. Two approaches for safe installation of reeled MLPs have therefore been proposed: pressurised and non-pressurised reeling. This paper focuses on reel-lay installation at atmospheric pressure. Nevertheless, the numerical analysis framework presented is also applicable to MLPs installed at elevated pressure in a scenario where they are subjected to bending after being depressurised. Small-scale mechanical tests were carried out to assess the effect of manufacturing and cyclic plastic bending on the tensile behaviour of the CRA liner. After full-scale bending trials had been undertaken, they were simulated numerically to demonstrate the suitability of the proposed numerical approach for predicting liner separation from the host pipe and subsequent wrinkling during high strain bending. To improve ovality prediction, which governs liner separation and wrinkling, the authors developed an advanced metal plasticity model.

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Investigations into the Fatigue Strength of CRA Lined Pipe

Cited by 5 publications

References 6 publications

Low Cycle Fatigue of Subsea Mechanically Lined Pipeline With Liner Imperfections

Low Cycle Fatigue of Subsea Mechanically Lined Pipeline With Liner Imperfections

Investigating an API X65 steel pipe cladded with alloy 625

Prediction of Liner Wrinkling During High Strain Bending of Mechanically Lined Pipe

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