Abstract: This invention provides a seismic joint for an underwater floating tunnel having: (a) a joint portion (i) having a transverse section essentially the same as that of the tunnel, (ii) being rigidly fastened to land at one end (A) thereof, and (iii) being elastically constrained to the tunnel at its other end (B) via a plurality of operably affixed means which performs an elastic function and a damping function; (b) a collar welded onto the external surface of the tunnel facing end (B) of the portion, said collar being capable of sliding on and along the external surface of the joint portion; and (c) a means for providing a water-tight seal between the internal surface of the collar and the external surface of the joint portion.

Abstract: A sensor in completely solid state for determining the concentration of a gas, in particular of hydrogen, is disclosed, which is essentially constituted by electrodes separated by a protonic conductor in the solid state, in which the solid-state reference electrode is constituted by a metal hydride, or a metal-alloy hydride.

Abstract: For sensing gaseous hydrocarbons in a gas mixture, a device consisting of two sensitive elements, one being a reference element, which are heated to different temperatures. The sensors, formed by subjecting films deposited by silk-screen processes to heat treatment at high temperature, are connected to an electronic evaluation circuit.

Abstract: A method for repairing and reinforcing pressure-supporting hollow bodies, in particular deteriorated underwater pipelines, using a tape formed from a plurality of layers.

Abstract: A method for monitoring the state of, and for locating any detachment of, the protective covering of immersed or buried pipelines or other metal structures subjected to cathodic protection with constant current, on the basis of the overall electrical resistance offered by the pipeline/covering/ground system, consisting of applying local sinusoidal wave excitation currents of different frequencies to the pipeline and measuring the corresponding voltage responses, then comparing the measured responses of the system to determine, on the basis of response differences or coincidences at the various frequencies, whether within the portion under consideration there is detachment with corrosion underway or whether there is simple covering decay.

Abstract: A sensor device for gaseous hydrocarbons includes two semiconductor oxide-based sensitive elements, one of which is a sensitive reference element and the other a sensitive measuring element, this measuring element being covered with a layer of electrically insulating porous material containing a dispersed noble metal. The two sensitive elements are formed by silk-screen processes, are connected to an electronic signal comparison system, and are maintained at different temperatures when in operation. The sensor has improved selectivity in determining gaseous hydrocarbons, in particular methane, even if high concentrations of interfering gases such as ethanol are present.

Abstract: A method for repairing and reinforcing pressure-supporting hollow bodies, in particular deteriorated underwater pipelines, using a tape formed from a plurality of layers.

Abstract: A method for repairing local damage to pipelines by applying a cylindrical cladding consisting of two cylindrical half-shells welded together to create an interspace, which is sealed by applying gaskets forced against the circular edges of the cladding, after which resin is injected into the interspace at high pressure.

Abstract: A nickel cermet contains 35-70% by weight of a metal nickel phase and 65-30% by weight of a zirconia phase stabilized in the cubic form with yttria, with, on X-ray diffraction analysis, said phases appearing as distinct and homogeneously distributed at a level lower than 1 .mu.m.This nickel cermet is obtained by preparing an aqueous solution containing a heat-decomposable zirconyl, yttrium and nickel salt, and an organic hydroxyacid or aminoacid, or a poly(acrylic acid); removing water from the resulting solution, under conditions of absence, or substantial absence, of decomposition phenomena, in order to separate a porous solid; calcining the porous solid, and reducing with hydrogen the product from calcination.The nickel cermet obtained in this way is useful as an anodic material for a solid oxide fuel cell (SOFC).

Abstract: An amorphous modified poly(2,6-dimethyl-p-oxyphenylene) (PPO) is described with a glass transition temperature (Tg) within the range of 170.degree.-220.degree. C., of which the macromolecules contain units having trialkylsilyl groups bonded to the nucleus and/or to the methyl: ##STR1## together with units having hydroxyethyl groups bonded to the nucleus and/or to the methyl: ##STR2## This modified PPO is prepared by metalating PPO with a metalating agent and reacting the formed metalated PPO with a trialkylsilyl halide and with ehtylene oxide in succession.The use of the thus modified PPO for the preparation of flat, including asymmetric, membranes useful in gas mixture separation processes is described.

Abstract: A process for preparing a modified, amorphous poly-(2,6-dimethyl-p-oxyphenylene) (PPO) comprises:(a) metalating PPO with a metalating agent, and(b) functionalizing such a metalated PPO by reacting the PPO with a trialkylsilyl halide and/or ethylene oxide; and is characterized in that the reaction of metalation is carried out in an inert liquid vehicle which contains PPO in an at least partially suspended solid form, by operating under metalating conditions of gradually adding metalating agent to such a suspension, either continuously or as discrete portions. Depending on the functionalizing agents used, and on the sequence of addition thereof, the process makes it possible to obtain PPO polymers which are modified with trialkyl-silyl, hydroxyethylene and/or ethyleneoxytrialkyl-silyl functional groups. The modified PPO polymers are particularly suitable for preparing flat membranes, including asymmetrical membranes, for the separation of gas mixtures.

Abstract: A solid-state sensor for determining the concentration of gases which can react with hydrogen, in particular, of oxygen, which includes a solid-state proton conductor into contact: on the one side, with a reference electrode, constituted in its turn by a metal hydride or a metal alloy, and on the other side with an electrode which catalyses the reaction of the gas to be detected, with said sensor being connected with a power feed system which supplies current or voltage impulses, and with a system which detects the value of potential after each impulse.

Abstract: A telescopic joint for repairing underwater pipelines laid at a great depth in which an annular sheath of steel having a yield point of not more than one half that of an outer sleeve of the joint is welded onto an inner cylinder, to create with the inner cylinder an annular chamber or interspace, the cylinder-sheath-sleeve assembly being guided in its telescopic movement by an inner tube welded coaxially to an end of the outer sleeve. The interspace is connected to an oil pump which under adequate pressure can cause the steel sheath to expand, to the extent that it yields, to interlock with the outer sleeve.

Abstract: Method for tightly jointing a sleeve to a submarine pipe laid on a very deep sea-bottom, characterized by the preliminary stages of providing a series of grooves on the inside surface of the sleeve, and of filling each one of said grooves with two half-rings made of a material collapsible under high pressures up to a 70% variation of its volume. A type of such a material is moreover described.

Abstract: A seal system for a spherical joint in which the metal seal ring is sandwiched coaxially between two wedge-shaped metal compression rings which are inserted into corresponding cavities in the front surfaces of the seal ring and are pressed against a metal stop ring by a series of flat springs which become preloaded as a result of forcing the female part of the joint onto the male part.

Abstract: An adjustable apparatus for supporting an underwater pipe suspended over a depression in great and medium depth sea beds, comprising an upper floating structure which enables the apparatus to be introduced into the sea and mounted over the pipe to be supported, and a lower structure constituted essentially by two telescopic legs able to rest on the sea bed, and two half saddles which adhere to the surface of the pipe to be kept raised.

Abstract: A method and apparatus for controlling the heat load in a plant fed with natural gas of variable calorific value and density consisting of withdrawing a portion of gas from the feed line, burning it in a special combustion chamber, withdrawing the combustion products from the chamber, determining the quantity of free oxygen contained in the dry burnt gas and varying the volumetric throughput of the natural gas on the main line.

Abstract: A pliable metallic joint for underwater pipelines laid at great depths, having a bellows-like section of a pliable metal or alloy, which is externally reinforced by a sturdy metal wire coiling positioned in the grooves of said bellows and which is internally reinforced by interlockingly arranged U-shaped rings and an axial undulated circular spring that allow a high degree of deformation and facilitate joining two pipes.

Abstract: A method for connecting in a sealtight manner a flanged sleeve to a pipe, especially for subsea gas and oil ducts, comprises the steps of introducing the free end of the pipe into the flanged sleeve with a clearance, expanding the pipe within the sleeve with the aid of a resilient expansible body which is axially compressed, releasing the axial compression and withdrawing the expansible body. The radial expansion is such as to expand the pipe at its plastic deformation condition and the sleeve within its elastic deformation limit, so that a union is achieved between the tube and the sleeve which is virtually indissoluble.