Hydraulic Hose Research Articles

脈動減衰用油圧ホースの特性解析

Hydraulic hoses having a tuning cable, called 'Resonator hoses', are frequently used to attenuate any pressure pulsation in a hydraulic system to reduce the noise inside an automobile. To optimize on the design of resonator hoses, a number of models have been developed in the frequency domain. However, a suitable model has yet to be found for simulating the complex configurations and non-linear phenomena in the pipelines including resonator hoses.This paper describes a time-domain simulation technique for resonator hoses and deals with the effects of the inner tube (tuning cable) as regards pulsation damping.In the modelling of a resonator hose, the hydraulic characteristics of the inner tube were studied using experiments. According to the experimental results, the leakage flowing through the inner-tube wall and the stiffness of the inner-tube were determined in the model. To simulate complex pipelines, the model of the resonator hose was added to the system simulation program (PAP) in which the method of characteristics was used. The simulated results were compared to the experimental ones to confirm accuracy.Using this simulation model, the effects of the stiffness and leakage characteristics of the inner-tube could be obtained by the transmission losses calculated from the simulated results. In addition, the transmission losses for the various combinations of the resonator hoses were discussed.

Wave Propagation Characteristics of Fluid Contained in a Finite-Length Hydraulic High-Pressure Flexible Hose. (1st Report. Mathematical Model Considering Anisotropic Viscoelasticity of Hose Wall and Boundary Conditions at Hose Fittings).

With the increasing use of high-pressure flexible hose in hydraulic equipment, the accurate knowledge of its dynamic response is required over a wide frequency range. We derive an analytical model for the wave propagation characteristics in a flexible hose with finite length by considering the coupled vibration of the hose wall and fluid in the hose, as well as the effect of the possible longitudinal resonance of the hose wall, where the hose wall is assumed to be linear, compressible and anisotropic viscoelastic with respect to the longitudinal and circumferential directions, while the fluid is assumed to be compressible and viscous and its motion to be laminar and axisymmetric. The membrane shell theory neglecting the radial inertial force is applied to the motion of the hose wall while taking into consideration the fluid pressure, and the Navier-Stokes equations and continuity equation which are simplified for an incompressible fluid are applied to the motion of the fluid after the fluid compressibility is equivalently converted into the compliance of the hose wall. A model is obtained in a transfer matrix representation which relates the pressure and flow ripples at two crosssections of a straight hose with fixed end support under constant fluid temperature and average pressure. In addition, the existing models for flexible, elastic and rigid lines may be considered as special cases of the model developed here.

TRANSMISSION CHARACTERISTICS OF FLUIDBORNE PRESSURE RIPPLES IN FINITE-LENGTH HYDRAULIC FLEXIBLE HOSES

The paper is concerned with the development of an analytical model for the transmission characteristics of fluidborne pressure ripples in hydraulic flexible hoses with finite length under anchored end conditions, as an extension to the previous researches for the hoses with relatively long length [1, 2]. The model is obtained in transfer matrix form relating the pressure and flow ripples at hose upstream and downstream, by considering the effect of possible longitudinal resonance of the hose in addition to the anisotropic viscoelasticity of the hose wall and the coupled vibration of the hose and the fluid. It is applied to predict the transfer matrix parameters of the hoses with different lengths. By the comparison of the predicted and measured results, it is shown that the model yields fairly good results in a frequency range up to around 3kHz and even may accurately predict what existing models failed to predict, i.e., the influence of longitudinal resonance of the hose wall on the wave propagation of fluid in the hose.

Evolution of Subsea Production Systems: A Worldwide Overview

The evolution in the use of subsea technology has seen advancement from one well in the Gulf of Mexico in 1961 to more than 750 wells in a wide variety of locations by the end of 1993. Along with the growth in numbers, the industry has seen rapid advances in technology, increased distances from the host facility, and water depth records. This paper gives an overview of the evolutionary changes in subsea applications, with emphasis on the most active regions and on some of the milestone installations that shaped the technology advance.

Observations of a pressurised hydraulic hose under lateral liquid impacts

The effects of ‘pin-hole’ failure of one pressurised hydraulic hose on its neighbour are investigated. A pressurised test hose was inserted into a custom testing apparatus and subjected to a series of ten short duration liquid impacts simulating the pin-hole failure of an initial hose. Subsequent displacements of the hose were filmed and plotted with respect to time. Three distinct pattern groups emerged which were used to explain the resultant damage to the hose. It was observed that the middle pattern, corresponding to impacts 6 and 7, appears to be the point where the very damaging hydraulic penetration mechanism became dominant and the outer layer of the hose failed. On completion of the ten impact series it was observed that a small hole on the outer surface of the hose gave way to a relatively large damaged area in the strength bearing inner braid material.

EXPERIMENTAL DESIGN AND ANALYSIS APPLIED TO HYDRAULIC HOSE WIRE CURL FORMATION

In the manufacturing of high-pressure hydraulic hose, controlling the hose wire curl has been a trial-and-error process because the important relationships were not understood. This article discusses the use of a 2k fractional factorial to determine sig..

Transmission of Vibration and Pressure Fluctuations Through Hydraulic Hoses

It is demonstrated that measured relationships between the vibration and pressure fluctuation at the input and output ends of hydraulic hoses, such as would be generated by a pump and transmitted to the subsequent circuit, can be described satisfactorily by two types of wave involving differing proportions of predominantly axial motion of the hose and the contained fluid, together with bending and torsional wave motion. The values of the wave properties required to do this are presented for four representative hose constructions, and the relationship of the properties to the construction is discussed.

Look at, Listen to Your Hydraulic System.

The key to preventive maintenance is an awareness not only of what makes the system go, but what the system is telling you it needs to keep going. Fluids and their levels, filters, gauges, hoses, and the sounds of pumps and motors all keep a running dialogue as to how they are doing. Topics covered in the article are hydraulic fluids, system monitors, hoses, pumps, and cylinders.

Experience with a new high pressure self boring pressuremeter in weak rock. Part II : Ground EngngV22, N6, Sept 1989, P45–52

This article describes the development of a new high pressure self-boring pressuremeter (rsbp), which allows the in situ direct measurement of strength and deformation characteristics of keuper marl for foundation design beneath a new United Kingdom power station site. A specific weathering scheme for the keuper marl at this site grades the material a to d according to the proportion of clay and condition of the joints; this is shown in table 1. The authors first establish the need for a self-boring pressuremeter which could be used in weak weathered rock, overcoming the problems of predrilling, allowing horizontal stress to be assessed directly and giving more reproducible values of modulus, less affected by membrane compression. The new instrument is designed to operate through h casing or in nx boreholes. It is 73.6 mm in diameter and 450 mm long; it can be expanded up to 12% cavity strain or 20 mpa. It uses a 2 rod drilling system but can be operated with a rotary rig. Rock cuttings are flushed to the surface using water or liquid polymer mud. Oil pressure is used to expand the pressuremeter; the thin composite membrane is made of nylon and neoprene. Transformer oil and power for electronics and transducer signal readings is supplied via 2 hydraulic hoses. Full details are given of the calibration tests used. The second part of this article is published in the September 1989 issue of ground engineering.

Testing and applications of wire-reinforced hydraulic hose

The examination of testing variables of a test which has been in use for at least 20 years puts into perspective its limitations when compared with actual operating conditions. It is shown that the presence of a flexing mode as well as impulse cycles is necessary. The type of hose to be used for any application (braided or spiral) is not as clear-cut today as one would have supposed a few years ago, and requires careful thought and analysis of laboratory impulse/flex results; but the result is now a better hose in service, with the test results in line with laboratory testing.

Factors affecting the impulse testing of hydraulic hose

Hydraulic hose testing is discussed with reference to the testing variables, the time taken to carry out the test, and in particular the correlation between service and laboratory conditions. From the results obtained a flexural impulse test is proposed as a basis for ISO DIS 8032.2. The parameters for a half omega configuration would be: temperature 93°C, pressure 150% of working pressure, rate of pressure rise 3000 bar/s, bend radius 0·5, pressure frequency 0·8 Hz, flexural frequency 1·07 Hz. A full omega configuration would give a more severe test.

The Rotary Multi-Plate Valve as an Integrated Control System of a Longwall Roof Support

Abstract An automatic control system of a longwall roof support is discussed. Hydraulic automatic control systems for longwall roof support have not met all requirements for such systems. Utilization of standard hydraulic elements to form a system that would comply with all demands leads to a very complicated structure with a large number of hydraulic hoses within and between adjacent supports. So, only simplified systems have been made. This paper describes the multifunctional valve that permits realization of any desired logic functions, while maintaining a compact form, and analyses its application as a fully hydraulic automatic control system of a roof support.

Mast Anchor for Hydraulic Soil‐Sampling Machines

AbstractCurrently, hydraulic soil coring machines allow rapid sample collection to a desired depth under ideal soil conditions; however, under less desirable conditions, sampling can be very time consuming, unsafe, or, at times, impossible. An apparatus was designed and constructed that can be attached to the mast of hydraulic soil sampling machines to anchor the machines to the soil, thus permitting soil sampling when vehicle weight is insufficient to sample to a desired depth. The mast anchor system described is faster and easier to use than the standard system presently used with many hydraulic sampling machines. The parts of the apparatus were an auger, hydraulic motor, guide‐rail frame, slotted‐auger plate, and hydraulic valve and hoses. In one soil sampling situation without additional anchorage, 76.2‐mm diam samples were obtainable to a depth of only 0.75 m, whereas with either standard or mast anchoring, samples were collected to 1.20 m. However, standard anchoring procedures required from 8 to 10 min to install and remove at each sample location, whereas the mast anchor required < 0.5 min.

Tactile Inspection Performance with and without Gloves

A firm whose inspectors tactually inspected hydraulic hose was interested whether gloves would help or hinder their inspectors. Eight female subjects, while blindfolded, each inspected 600 hoses–150 for each of the four glove conditions (bare hand, surgeon's gloves, Playtex gloves, and vinyl-impregnated gloves). The subjects indicated whether the hose was acceptable, defective due to diameter, or defective due to surface roughness. The data was divided into that obtained when the hoses were acceptable and that when there was a defect. For good hoses, gloves did not affect error rate for either diameter defects or surface defects. For defective hoses, gloves did not affect error rate for either diameter defects or surface defects. Thus the decision whether or not to wear gloves can be made on other criteria (such as protection of the hand vs abrasion or chemicals). A signal detection analysis was made. Some other ergonomic suggestions for improved inspection performance are given.

Physical Scale Modelling of Electrothermic Thawing of Permafrost For Alleviation of Frost Heave Problems In Chilled Gas Pipelines

Abstract The artificial thawing of permafrost beneath chilled gas pipelines by electrical current flawing through the frozen medium Is studied by means of scaled physical models. Techniques are described whereby, by use of a minimal number of electrodes embedded in the frozen medium, extended zones can be thawed beneath the pipeline so that the pipe can settle and frost heave stresses can be relieved. INTRODUCTION The design and construction of pipelines in cold regions entail special problems. It is well known, for instance, that pipelines passing through zones of continuous and discontinuous permafrost may cause ground slumping or frost heaving if adequate design measures are not taken. As an example, over half the length of the 1.22-m-diameter Alyeska oil pipeline has had to be elevated on special piles to prevent the warm oil from thawing the underlying ground ice, which in turn would have caused unacceptable subsidence of the pipe. Plans for the ill-fated 1.22-m-diameter Mackenzie Valley gas pipeline called for chilling the gas so that the cold pipe could be buried and not cause thawing of permafrost and ground ice. It was evident, however, that in zones of discontinuous permafrost, freezing of the soil around the chilled pipe would, over a period of years, cause frost heave and attendant unacceptable differential stresses in the pipeline. The route of the recently approved Alcan gas pipeline presents geotechnical problems -that are similar to those of the Mackenzie Valley route. It is again deemed advisable to bury the pipeline and to chill the gas in order to avoid ground thawing and subsidence. As before, this leads to problems in zones of discontinuous permafrost due to soil freezing and frost heave. Various proposals have been advanced for overcoming the frost heave problem. Initially, it was thought that an earth berm placed above the pipeline would weight down the pipe to counter eventual frost heave pressures. It now seems, however, that frost heave pressures are too great to be controlled in this fashion. Other approaches that have been suggested include fishing. Construction of the packer element is very similar to a high-pressure hydraulic hose with steel braided carcass layers. Unlike a hydraulic hose, the packer expands as required when internal pressure is applied. Expansion is allowed by special braid angles in the packer carcass. Like a hydraulic hose, the packer element also has metal collars on both ends. The collars anchor both ends of the steel braid cables, and are threaded to fit the packer assembly. Limitations of the Equipment Inflatable packer equipment is limited mainly by the differential pressure holding ability of the packer elements. However, this is affected to a large extent by the diameter that the packer element has been inflated to. With the hole in good condition and close to gauge, the packer elements have had no trouble holding differential pressures in excess of 30,000 kPa. However, because one of the main uses of inflatable packer equipment is in washed-out holes.

The behaviour of braided hydraulic hose reinforced with steel wires

Measurements are reported of the variation with pressure of the elastic strain in the wires of the outer braid of a two-braid high pressure hydraulic hose. Strain measurements were made with a Solex pneumatic extensometer. The performance of the extensometer was checked by comparing the measured and calculated strains for the wires in a single braid hose. Good agreement was found. Surprisingly little hysteresis was observed in the wire tensions on loading and unloading. Hysteresis in the length changes of the hose was more marked. Measurement of the relative displacement of the edges of adjacent tapes of wires led to the conclusion that frictional forces at the points where braid wires cross is a major source of hysteresis. An analysis is presented which was used to calculate both the elastic strains in the braid wires and the length change of the hose on pressurisation. The analysis takes account of the compressibility of the rubber between the two braids but ignores constraints arising from friction or from the rubber. The measured strains and length changes agreed sufficiently well with the predicted values to justify the use of the analysis for hose design. Using this analysis, information is assembled about the effect of braid angle on wire tensions and length change; this leads to a proposal for the ideal values of the inner and outer braid angles in a particular case.

Testing requirements for hydraulic hose

The performance required of hydraulic hose used for materials handling and especially as used on earth moving vehicles is of necessity much higher than hose used on say agricultural tractors and aircraft. This extra performance is not only one of pressure needs, but also includes extremes of temperature with a fairly high level of oil resistance at high volume flows, plus flexing at very small bend radius in some instances. Compound design and the correct choice of polymer is critical under such conditions, as also is the type and combination of the reinforcement materials, which can include both textile and fine wires of high tensile strength. All of these design features in the correct permutation make the difference between a mediocre field performance and a performance that is extremely reliable, safe and satisfactory. Hose design is discussed in the context of these parameters, together with testing procedures not only in current use but future requirements under discussion and test at national and international levels. The new secant square wave pressure impulse curve is included, together with superimposed flexing of various formats, and the results and effects of such laboratory tests are critically examined in the light of the operating conditions and quality assurance.

A method for achieving effective load transfer between the inner and outer layers of a two-layer braided high-pressure hydraulic hose

A method is proposed for accommodating the misfit between two layers of a braided hose. This is achieved by laying the inner and outer braids at angles that lie symmetrically on either side of the equilibrium helix angle of tan −1 ✓2 for a single-layer hose. The theory of the method is developed and it is shown that a difference of helix angles of 4° or more will accommodate the fractional radial misfit of 3 × 10 −3 existing in a particular sample of hose. An analysis of the wire tensions in a pressurised hose, assuming constant inter-layer volume, revealed that seriously unequal tensions exist in the two layers if the two helix angles lie asymmetrically about tan −1 ✓2. The process of taking up misfit, now proposed, generates asymmetry. However this asymmetry and the associated inequality of wire tension decreases as the difference of braid angles increases. Guided by this generalisation, it is demonstrated that an acceptable hose design is achieved if the inner braid is laid at an angle of 59·74° and the outer braid at 49·74°. The geometrical changes that take up the misfit at low pressures produce an extension of the hose of 0·65% and reduce the braid angles by about 1 4 ° . The ratio of final tensions in the two layers is 0·93. The analysis in the paper leads to the conclusion that manufacturing uncertainties in the angle at which a braid is laid can generate serious inequalities of wire tension. In the specific illustrative example analysed here an uncertainty of ±1° in braid angle will cause the ratio of wire tensions to vary, but it never falls below a value of 0·63.

Value of Heave Compensators to Floating Drilling

This examination of the motion compensator concludes that it is one of the biggest advances made in offshore drilling in recent years. Analysis of the operation of rigs equipped with motion compensators indicates a saving of about 16 days per rig-year. Optimum bit loads allow maximum penetration rates and increased bit life. Another advantage is safety in penetration rates and increased bit life. Another advantage is safety in well killing and BOP-stack handling. Introduction Before the design and introduction of the first heave or drillstring compensators, variations in the distance between the bit and the drilling level owing to wave action were accounted for with the aid of bumper subs. As offshore exploration moved into deeper and rougher water and failures achieved new dimensions in terms of cost, an alternate and more flexible method was sought. The result was the motion compensator first produced in the late 1960's when Vetco Offshore, Inc., installed a twin-cylinder model on the Wodeco IV, a drill barge working in the Santa Barbara channel. This equipment operated successfully within its design limits, and the concept of hydraulic or pneumatic heave compensation was proved viable. At least seven companies are now engaged in the design and manufacture of compensators. Each machine has a mode of operation peculiar to itself and possesses its own series of peculiar to itself and possesses its own series of problems. Shell Expro has been able to analyze the problems. Shell Expro has been able to analyze the performance of both the Vetco and the RUCKER Shaffer performance of both the Vetco and the RUCKER Shaffer models since they were installed on Shell-contracted rigs in the North Sea in Jan. 1974. Operating problems of other models such as the Western Gear Single Cylinder and the Ocean Science and Engineering, Inc., Crown Compensator have been assessed wherever possible. Savings in terms of weather down-time, bit life, and personnel and equipment safety have been observed during the latter part of the winter and throughout the summer of 1973-74 and are discussed in some detail. Now that drilling has moved further north, almost to latitude 62 degrees, the weather has produced a greater impact on rig operations. West of the Shetland Islands, where extremely long swells have been observed with correspondingly high heaves, one rig would certainly have been shut down without a heave compensator. Drilling has continued successfully in weather conditions producing heaves in excess of 12 ft and blowout-preventer producing heaves in excess of 12 ft and blowout-preventer (BOP) stacks have been landed with similar movement. Principles of Operations Principles of Operations Motion compensators may be located in the crown block or between the traveling block and the hook; they may operate either pneumatically or hydraulically, or by a combination of the two. During rig heave conditions, the operating medium is forced back and forth by means of hoses between the compensator's piston/cylinder arrangement and a number of pressure bottles or accumulators (Fig. 1). In the traveling-block units, hydraulic hoses hang from their respective standpipes in the derrick, whereas the compensated crown eliminates these - all hoses are fitted to the outside of the derrick. The mode of operation may be considered active or passive, or a hybrid of the two. In the purely passive passive, or a hybrid of the two. In the purely passive system (Fig. 2), the activating fluid results in air being compressed and expanded in and out of a bank of accumulator bottles; use is made of the adiabatic gas law: p1V1k = p2V2k V1 k p = p2 − p1 = p1 [(--------) −1],.......(1) V1−AX JPT P. 938

Dynamic response of hydraulic hoses

Dynamic response of hydraulic hoses