Sheath bonding

When lengths of three minor sections are different, it leads to unbalance of the induced voltages, which causes sheath currents. Flowever, when there are more than a couple of major sections, it is a common practice to design 

Single-point bonding as a part of a cross-bonded cable. 

This situation is often observed in actual installations as the number of minor sections is not determined considering the cross-bonding. Rather, it is determined to reduce the number of joints as much as possible, considering the cost. 

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Morgan, P. D. and Double, E. W. W., /4 Critical Resume of a.c. Corrosion from the Standpoint of Special Methods of Sheath Bonding of Single Conductor Cables, British Electrical and Allied Industries Research Association Technical Report F/T 73 (1934)... 

In triple layer approximations the location of each adsorbate with respect to the surface must be specified. Protons and all ions assumed bound as inner-sphere complexes (specifically or chemically adsorbed species) are assumed to lose part of their hydration sheaths, bonding directly to sites in the surface itself. Adsorbates assumed to remain hydrated, forming outer-sphere surface complexes, are assigned to the OHP. In the intrinsic equilibrium constants for adsorption reactions, K ", the activities of ions transferred from solution to the surface are corrected for the electrical potential they experience, % or (27). 

KG-12" Copper sheath bonded to core. Surface usually coated with borax to reduce oxidation. Expansion Radial,... 

Adhesives are also used in the manufacturing of prefabricated sections or assemblies. Examples include complete wall sections with the sheathing bonded to wood frames roof sections with sheathing bonded to j oists and rafters to provide T-beam action and box beams and other types of composite beams for joists or rafters. ] Phenolic adhesives are used in the fabrication of laminated beams and trusses. Epoxies are also widely used for bonding and the repair of concrete. ]... 

As mentioned in the previous section, the limitation of the sheath voltage is an important factor that decides sheath bonding and other cable system designs related to the sheath. There are two types of limitations in the sheath voltage (1) the continuous voltage limitation and (2) the short-term voltage limitation. 

Steric Factors. Initially, most of the coUisions of fluorine molecules with saturated or aromatic hydrocarbons occur at a hydrogen site or at a TT-bond (unsaturated) site. When coUision occurs at the TT-bond, the double bond disappears but the single bond remains because the energy released in initiation (eq. 4) is insufficient to fracture the carbon—carbon single bond. Once carbon—fluorine bonds have begun to form on the carbon skeleton of either an unsaturated or alkane system, the carbon skeleton is somewhat stericaUy protected by the sheath of fluorine atoms. Figure 2, which shows the crowded hehcal arrangement of fluorine around the carbon backbone of polytetrafluoroethylene (PTFE), is an example of an extreme case of steric protection of carbon—carbon bonds (29). 

The nonbonding electron clouds of the attached fluorine atoms tend to repel the oncoming fluorine molecules as they approach the carbon skeleton. This reduces the number of effective coUisions, making it possible to increase the total number of coUisions and stiU not accelerate the reaction rate as the reaction proceeds toward completion. This protective sheath of fluorine atoms provides the inertness of Teflon and other fluorocarbons. It also explains the fact that greater success in direct fluorination processes has been reported when the hydrocarbon to be fluorinated had already been partiaUy fluorinated by some other process or was prechlorinated, ie, the protective sheath of halogens reduced the number of reactive coUisions and aUowed reactions to occur without excessive cleavage of carbon—carbon bonds or mnaway exothermic processes. 

Polytetrafluoroethylene and fluorinated ethylene-propylene are the only resins composed wholly of fluorine and carbon. The polymer consists of fluorine atoms surrounding the carbon chain as a sheath, giving a chemically inert and relatively dense product from the strong carbon-fluorine bonds. Polytetrafluoroethylene must be molded at high pressure. Fluorinated ethylene-propylene c.m be injection molded and extruded as thin fdm. Both plastics have exceptional heat resistance... 

Platinum and rhodium-platinum and iridium-platinum alloys are frequently employed to line and sheath autoclaves, reactor vessels and tubes, and a wide range of equipment. Linings are generally 0-13 mm to 0- 38 mm thick, and for certain applications co-extruded platinum-lined Inconel or other metal reactor or cooling tubes are fabricated. In such cases the platinum is bonded to the base metal, but in all other instances platinum linings are of the loose type. 

Cable sheaths may be covered with paper and hessian wrappings impregnated with bituminous compounds or with extruded or taped plastics outer sheaths. At pinholes or discontinuities in protective coatings the sheath will be particularly liable to electrolytic corrosion in stray-current areas, and it is desirable to supplement this form of protection by drainage bonds or direct cathodic protection. 

If one of the structures to be bonded is the sheath or metallic armouring of an electric supply cable, special precautions will be necessary to ensure that the voltage rise at the bond in the event of an instantaneous earth fault on the power-supply system does not endanger personnel or equipment associated with other buried structures. The bond and any associated current-limiting device should be suitably insulated and of adequate current-carrying capacity. 

Account must also be taken of small alternating currents which may be diverted from the sheath of a power supply cable by a bond connected to nearby buried structures. Such currents may be sustained for long periods and if they are diverted to the sheaths of telecommunication cables noise may be induced in the telephone circuits. 

The subunit eomposition is such that the intraeellular release of the viral genome horn its coat involves only the dissociahon of non-eovalently bonded subunits, rather than the degradation of an integral protein sheath. 

The species HjO is subject to further hydration in the usual manner. Its primary sheath contains three water molecules linked through electrostatic forces, and in part through hydrogen bonds (i.e., the ion with its primary solvation sheath can be formulated as H9O4+). 

Since it is well known that alcohols form strong hydrogen bonds, it is very probable that the alcohol in this step hydrogen bonds to the silicic acid (or acids) produced in it, and as a result creates a protective sheath around each silicic acid molecule. This sheath is clearly very important in framework retention in view of the reactivity of silicic acids. 

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