Provided is a hollow structure for fuel includes a polyamide resin layer (A), a polyamide resin layer (B) , and a polyamide resin layer (C) in this order from an outside. The polyamide resin layer (B) contains a polyolefin, the polyamide resin layer (C) contains a conductive substance, and an amount of an eluate in an eluate test using a pseudo fuel in the hollow structure for fuel is 25 g/m.sup.2 or less.

Disclosed are methods and apparatus for identifying non-metallic subterranean structures using amorphous metal markers associated with the structures. Some examples will include the amorphous metal in the form of one or more sections of an amorphous metal foil within a protective enclosure sufficient to physically isolate the amorphous metal foil from the surrounding Earth. The amorphous metal foil and enclosure may be in the form of a tape which either will be secured to, or placed proximate the subterranean structure, which may be, for example, a pipe or conduit, or other non-metallic structure.

A fluid conduit includes a first portion and a second portion disposed at least partially around the first portion. The first portion may include an extruded thermoplastic. The second portion may include a plurality of layers formed via fiber reinforced thermoplastic tape, tows, and/or fabric. The first portion and the second portion may be substantially rigid and may include concentric cylindrical cross-sections. The fiber reinforced thermoplastic tape, tows, and/or fabric may include nano-additives and/or micro-additives.

A rigid pipe-in-pipe structure for subsea transportation of fluids includes inner and outer pipes defining a thermally-isolating annulus between them. Thermal insulation material is disposed in the annulus. The outer pipe is of metal, preferably carbon steel. The inner pipe is a polymeric composite structure of bonded layers including a first, radially outer tubular polymeric electrically insulating layer, which can be of pure polymer, surrounding a second, composite layer including carbon fibers, preferably continuous fibers, embedded in a polymer matrix. Conveniently the second layer is a heating layer in which the carbon fibers conduct electricity to heat the inner pipe. The inner pipe can also comprise a radially inner tubular polymer layer within the second composite layer.

A fluid transfer conduit comprising: an electrically conductive tube of fibre reinforced polymer composite material which has an electrically conductive outer surface and an electrically conductive inner surface; and on at least one axial end of said conduit, a non-electrically-conductive band formed on either the outer surface or the inner surface of the electrically conductive tube. Forming a non-electrically conductive band on the end of the conduit electrically isolates the electrically conductive outer surface of the conduit from the electrically conductive metal socket into which it is to be inserted.

Described here are multilayer tubes including a plurality of layers. The multilayer tubes include an outermost layer, including a first polyarylene sulfide (PAS) and from 5 wt. % to 30 wt. % of an impact modifier. The multilayer tubes also include an innermost layer including a second PAS and from 0.1 wt. % to 10 wt. % of an electrically conductive filler. Significantly, each layer in the multilayer tube comprises a PAS. The outermost layer is the sole layer comprising an impact modifier and the innermost layer is the sole layer comprising an electrically conductive filler. At least in part because of compatibility of PAS based materials with one another for interfacial bonding, the multilayer tube is free of tie layers.

The present invention provides a polyamide resin composition not only having an appropriate melt viscosity despite addition of a conductive filler thereto but also having excellent moldability, conductivity, low-temperature impact resistance, and fuel barrier properties. The present invention is a polyamide resin composition containing specific amounts of a polyamide, a modified resin, and a conductive filler. The polyamide contains: dicarboxylic acid units containing 50 mol % or more of terephthalic acid units and/or naphthalenedicarboxylic acid units; and diamine units containing 60 mol % or more of aliphatic diamine units having 4 to 18 carbon atoms, and has terminal amino groups in an amount of 5 to 60 mol/g. The modified resin has been modified with an unsaturated compound having a carboxyl group and/or an acid anhydride group. In the polyamide resin composition, a difference between the number of moles (M.sub.I) of the terminal amino groups of the polyamide and the number of moles (M.sub.II) of the carboxyl groups and the acid anhydride groups of the modified resin in 1 g in total of the polyamide and the modified resin is 5.0 mol or more and less than 4.0 mol, and the number of moles (M.sub.II) is more than 4.0 mol.

There is provided a flow rate adjustment apparatus including a main body inside which a fluid flow passage that guides a fluid has been formed, in which the main body is formed of a conductive fluorine resin material containing a fluorine resin material, and a carbon nanotube dispersed in the fluorine resin material, and in which a volume resistivity of the conductive fluorine resin material is more than 1.010.sup.3 .Math.cm and less than 1.010.sup.4 .Math.cm.

A fluid circulation device having at least one fluid circulation tube, a first coupling sealingly coupled to a first end of the tube and a second coupling sealingly coupled to a second end of the tube in such a way as to allow the circulation of fluid between said two couplings via the tube. The device further has separate electronic elements. The tube has at least one conductor track extending along an outer surface of the tube. The track is suitable for transmitting at least one signal and arranged to engage with the abovementioned electronic elements.

A wiring incorporated resin pipe includes a tubular shaped sheet formed in an approximately tubular shape at an interval so that a slit is formed between both ends in a transverse direction, a wiring unit arranged in the tubular shaped sheet along a longitudinal direction of the slit in an inner side of the slit and a resin material filled in a gap formed by matching surfaces of the slit of the tubular shaped sheet and the wiring unit to thereby seal the matching surfaces of the slit of the tubular shape sheet, in which conductive wires for wiring are laid inside the wiring unit in the longitudinal direction.