Characterisation of slug flow conditions in pipelines for fatigue analysis
- Authors: Reda, Ahmed , Forbes, Gareth , Sultan, Ibrahim
- Date: 2011
- Type: Text , Conference proceedings
- Full Text: false
- Description: Understanding the problem of slug flow induced fatigue damage is of particular importance to the reliable operation of pipelines. Slug flow across unsupported pipeline spans, pipeline crossings or vertical engineered buckle initiators, i.e. sleepers, produces dynamic motion in the pipeline resulting in cyclic fatigue stresses. In some cases, the dynamic effects will cause the pipeline to fail at a point of stress concentration. In other cases, however, these effects may be negligible. The current literature provides no guidance as to when the dynamic effects of slug flow must be considered. This paper gives guidance and describes how fatigue due to slug flow in pipelines, which would normally require dynamic analysis, can be quantified using simplified quasi-static analysis. The paper also presents a design process which could be used by pipeline engineers to determine the level of analysis needed, before embarking on more complex and expensive dynamic finite element. Copyright © 2011 by ASME.
A surrogate model for evaluation of maximum normalized dynamic load factor in moving load model for pipeline spanning due to slug flow
- Authors: Sultan, Ibrahim , Reda, Ahmed , Forbes, Gareth
- Date: 2012
- Type: Text , Conference proceedings
- Full Text:
- Description: Understanding the problem of slug-flow-induced fatigue damage is of particular importance to the reliable operation of pipelines. Slug flow, across unsupported pipeline spans, produces dynamic vibrations in the pipeline resulting in cyclical fatigue stresses. These dynamic effects will cause the pipeline to fail at a point of stress concentration if proper design procedure is not followed. The response of a pipeline span, under the passage of slug flow, can be represented by dynamic load factors that are functions of the speed ratio and damping characteristics of the span. The aspects of these functional relationships are investigated, in this paper by conducting multiple simulations at different speed ratios and damping factors. The data obtained from the steady state Fourier expansion will, consequently, be used to produce a surrogate model with a level of accuracy that adequately qualifies it for use in determining dynamic loading of pipelines. The closed-form surrogate model can be used to eliminate the need to employ costly mathematical procedures or finite element packages for the analysis. The model will also provide a solid ground for optimization studies and help designers gain an insight into how various model parameters impact the system response. This paper will demonstrate the aspects of a proposed surrogate model and endeavor to obtain parameter domains within which the model's reliability is ensured. A numerical example will be demonstrated to prove the concepts presented in the paper and confirm the validity of the proposed model. Copyright © 2012 by ASME.
- Description: C1
Characterization of dynamic slug flow induced loads in pipelines
- Authors: Reda, Ahmed , Forbes, Gareth , Sultan, Ibrahim
- Date: 2012
- Type: Text , Conference proceedings
- Full Text: false
- Description: The flow of a liquid mass, i.e. a 'slug', inside thin-walled spanning pipelines, produces a lateral traversing force. This moving force initiates dynamic stresses within the structure and is often critical when assessing structural fatigue. Moving slugs in spanning pipelines may be modeled as either a moving concentrated force or a moving mass when investigating the vibration response of the pipeline under the passage of a slug flow. The moving concentrated force model only yields accurate results when the mass of the slug is small in relation to that of the pipeline; although, the moving mass model should be used instead when the slug's mass cannot be regarded as small in relation to the mass of the pipeline. The modeling of a moving concentrated force is much more readily implemented than that of a moving mass. Thus, the aim of this paper is to identify those situations where the simplification of considering a moving concentrated force can be made, or indeed if dynamic analysis is even required. Results are given in this paper to quantify when the two modeling techniques begin to differ significantly. It is intended that this paper will assist pipeline engineers discriminate between which appropriate conditions to use for either of the two different models of a traversing concentrated force/mass over a structure. Copyright © 2012 by ASME.
- Description: C1
Necessity and suitability of in-line inspection for corrosion resistant alloy (CRA) clad pipelines
- Authors: Reda, Ahmed , Shahin, Mohamed , Sultan, Ibrahim , Amaechi, Chiemela , McKee, Kristoffer
- Date: 2023
- Type: Text , Journal article
- Relation: Ships and offshore structures Vol. 18, no. 9 (2023), p. 1360-1366
- Full Text: false
- Reviewed:
- Description: This paper outlines the necessity and suitability of in-line inspection (ILI) using intelligent pigging for Corrosion Resistant Alloy (CRA) subsea clad pipelines through an incident that occurred during a baseline survey performed on a 20-inch y CRA clad pipeline of 2.7 km long. In this incident, an ultrasonic (UT) intelligent pigging tool was impacted and resulted in damage to the pipeline's clad layer. This damage was due to the collosion of the sealing pigs with the rear of the UT intelligent pigging tool, resulting in the UT intelligent pigging tool to get stuck and stop at the end of the pipeline. Pressure surges were used to dislodge the UT intelligent pigging tool, but caused the UT pig to be crashed into the pig receiver, resulting in severe damage to the UT pigging tool. The analysis of the metal swarf recovered from the pig receiver revealed that the damage was limited to the pipeline's clad layer. It was also revealed that a bypass has occurred to the sealing pigs causing damage to the sensor carriers of the intelligent pigging tool.