This paper describes a tilt table test method for measuring the shear resistance between flowlines and supporting soils. This shear resistance is important in considering buckling and walking in the design of flowlines. A significant challenge in measuring the shear resistance is the very low effective normal stresses that exist at the interface in field conditions. Since the measured stresses will be small, even small amounts of friction in a test device can adversely affect the results. The tilt table method overcomes this problem by using gravity to apply the normal and shear stresses to the soil-flowline interface, eliminating the need for a mechanical loading system. A set of test results is presented to demonstrate how the test method can be used to measure the resistance between the flowline and the soil. These results illustrate that the type of flowline coating and the effective normal stress affect the shear resistance.
Wear rates obtained from different investigators could vary significantly due to lack of a standard test method. A test methodology is therefore proposed in this paper to enable the steady-state wear rate to be determined more accurately, consistently, and efficiently. The wear test will be divided into four stages: (i) to conduct the transient wear test; (ii) to predict the steady-state wear coefficient with the required sliding distance based on the transient wear data by using Yang’s second wear coefficient equation; (iii) to conduct confirmation runs to obtain the measured steady-state wear coefficient value; and (iv) to convert the steady-state wear coefficient value into a steady-state wear rate. The proposed methodology is supported by wear data obtained previously on aluminium based matrix composite materials. It is capable of giving more accurate steady-state wear coefficient and wear rate values, as well as saving a lot of testing time and labour, by reducing the number of trial runs required to achieve the steady-state wear condition.
Myocardial Performance and Baroreceptor Reflexes in Preterm Neonates: An Echocardiographic Evaluation Using the Tilt Table Test Method