Liner Hanger Rating Methodologies Validated with Physical Testing

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Abstract Currently there are no industry standards specific to the design of liner hangers that provide guidance for determining equipment capacity. The demand for increased pressures, temperatures, and load capacities within stringent space constraints has added complexity to liner hanger design. As wall thickness decreases, capacities are more sensitive to geometrical features and imperfections such as slots, grooves, ovality, and end effects. Classical engineering calculations become increasingly inaccurate as liner hanger geometries become more complex, driving a demand for more precise methods of design verification and validation. Advanced 3-D finite element analysis (FEA) with elastic and elastic-plastic analysis and non-linear geometrical behavior is being used to more accurately quantify stress levels and identify sources of instability in complex liner hanger geometries. The addition of axial slots to a cylindrical pressure vessel result in localized bending stresses which are often overlooked when using only classical engineering calculations for cylindrical members. FEA captures these bending effects, resulting in more accurate ratings. Additionally, external pressure failures due to instability are difficult to capture with classical engineering calculations. Unlike hand calculations, 3-D FEA allows the user to accurately detect instability in liner hanger bodies with complex geometries and end effects. Although 3-D FEA is more accurate than classical engineering calculations, it is imperative that the inputs and assumptions that go into the model accurately represent the physical conditions of the validation test and end use. Internal and external pressure tests have been conducted and the information obtained was used to validate the FEA verification methods. By using a combination of verification analysis with advanced FEA and test validation, an accurate and proven rating methodology for liner hanger systems has been developed. Details about the calculations, FEA, testing, safety margins, and a proposed methodology for rating liner hangers are presented.