Hydraulic Pressure Test Research Articles

Characteristics of wire-space-type submarine optical cable

A new type of submarine optical cable, called wire space cable, is proposed for utilisation in shallow sea areas. In the cable, optical fibres are inserted into spaces formed between stranded wires, which are used as tension members. It has been found from a cable pulling test that nonarmoured cable elongation at 8000 m in water depth is 0.3% and armoured cable elongation at 6000 m is 0.5%. Furthermore, a hydraulic pressure test has shown that single-mode-fibre loss at 1.3 μm wavelength does not increase up to a water depth of 2700 m.

Nuclear Grout Monitoring on Offshore Platforms

Summary Over the last 4 years, the Atomic Energy Research Establishment (AERE) at Harwell, England, has developed nuclear instrumentation and tracer techniques to measure the density and movement of grout used in the installation of steel jackets to the seabed. These methods have been applied to a number of steel jackets in the North and Celtic seas where weather conditions can affect greatly the application of traditional methods of visual inspection. Introduction Radioisotope density gauges capable of indicating the presence and accurately measuring the density of cement grout during and immediately after grouting of sleeve/pile annuli have been developed by AERE. They have been used successfully on a number of structures in the North and Celtic seas and since 1979 have been produced and used by Wimpey Laboratories Ltd. under license. These instruments, of a type well-established in a wide variety of industries, have been developed for subsea operation at depths exceeding 1,640 ft (500 m). Nuclear gauges also have been used for control at the grout mixing plant, thus enabling more constant grout densities to plant, thus enabling more constant grout densities to be achieved during pumping operations. Radioisotope tracers have been used for a considerable time for a number of types of investigations in oilwell drilling and logging. One such method has been used to monitor the movement of grout around the outside of insert piles of a structure. This method used powdered glass, size-matched to the cement and containing Scandium 46, which is introduced into the grout, and its progress up the outside of the pile is monitored by means of radiation detectors suspended within the insert pile. Grout Density Measurement Description of Gauges The grout density gauges are based on measurement of the decrease in intensity of a beam of gamma radiation after passing through grout as it flows between a radioactive source and radiation detector. Typical gauge arrangements are shown in Figs. 1 and 2. Calibration of the gauge gives the following relationship for the density of grout. I Pg =Pref -A 1n --,.................................(1) Pg =Pref -A 1n --,.................................(1) B where I is the ratio of gamma radiations passing through grout and water, respectively, and A and B are calibration constants. In practice, it is convenient to use seawater as the reference fluid since the measurement of count rate can be made in situ, with constant geometry of the gauge to the surrounding steel structure, and immediately before grouting commences. A typical calibration curve is shown in Fig. 3. The gauges used on offshore platforms have included sources of either Caesium 137 [half-life of 30 years and gamma energy of 0.66 MeV (0.1 pJ)] or Iridium 192 [half-life of 74 days and gamma energies of 0.3 to 0.6 MeV (0.05 to 0.1 pJ)]. The latter isotope, although of a weaker and marginally more favorable gamma energy for this application, has the disadvantage of a relatively short half-life if major construction holdups delay float out or installation of the structure. The radiation detector, a geiger counter specially constructed in a waterproof housing, has been tested to withstand shock loads of up to 300 g (3000 m/s 2), hydraulic pressure tests at more than 1,640 ft (500 m) of head for periods of several weeks, vibration tests over a wide frequency range at accelerations of up to 15 g (147 m/s2), and over a 40 degrees C temperature range. JPT P. 425

Pressure Vessels of High Proof Strength Warm Worked Stainless Steel

In order to establish the necessary data to enable high proof strength austenitic stainless steels to be used for the fabrication of pressure vessels, plates were produced with an increased proof stress obtained by the warm working method. The laboratory investigation then showed that it was practicable to raise the proof strength of this material to twice the normal value for fully softened plate with an improvement in the ultimate tensile strength. Following this, two similar experimental vessels were manufactured in normal and high proof strength 18% Cr-8% Ni-Ti stabilized steel and these were subjected to hydraulic pressure testing. The vessel tests showed how stainless steel vessels behave under static pressure application at room temperature, and the behaviour of the high proof strength vessel indicated that it would be quite safe at nearly double the design pressure for the fully softened vessel. The strain hardening of stainless steel, fabricating techniques and weld quality have also been investigated and these are reported upon in the paper. Proposals for design stress criteria and stress values are made in relation to an examination of existing pressure vessel codes and the experimental data.

Effect of a Longitudinal Static Pressure upon a Magnetostrictive Ferrite

Double-dumbbell transducer elements of two commercial nickel-copper-cobalt-ferrous ferrites (Ferroxcube 7A1 and 7A2) with acoustic “pressure-release” material at each end were placed between the jaws of a hydraulic pressure testing machine. The effective electromechanical coupling coefficient for the sample was measured for various magnetizing currents and static loads. As the load was increased to 5600 lb, corresponding to 4600 psi in the narrow “limbs” of the element, the effective coupling coefficient at optimum bias decreased from 0.21 to 0.05, and the clamped inductance (which is proportional to the incremental permeability) decreased by 40 per cent.

Effect of High Static Pressure upon a Magnetostrictive Ferrite

A double-dumbbell transducer element of a commercial nickel-copper-cobalt-ferrous ferrite (Ferroxcube 7AI) with acoustic “pressure-release” material at each end was placed between the jaws of a hydraulic pressure testing machine. The effective electro-mechanical coupling coefficient for the sample was measured for various magnetizing currents and static loads. As the load was increased to 5600 lb, corresponding to 4600 psi in the narrow “limbs” of the element, the effective coupling coefficient at optimum bias decreased from 0.21 to 0.05. the resonant frequency increased by 8%. and the clamped inductance (which is proportional to the incremental permeability) decreased by 40%.