|
Salvage Diving
Salvage diving is the diving work associated with the recovery of all or part of ships, their cargoes, aircraft, and other vehicles and structures which have sunk or fallen into water. In the case of ships it may also refer to repair work done to make an abandoned or distressed but still floating vessel more suitable for towing or propulsion under its own power. The recreational/technical activity known as wreck diving is generally not considered salvage work, though some recovery of artifacts may be done by recreational divers. Most salvage diving is commercial work, or military work, depending on the diving contractor and the purpose for the salvage operation, Similar underwater work may be done by divers as part of forensic investigations into accidents, in which case the procedures may be more closely allied with underwater archaeology than the more basic procedures of advantageous cost/benefit expected in commercial and military operations. In 1978, the U.S. Navy Specia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cargo
Cargo consists of bulk goods conveyed by water, air, or land. In economics, freight is cargo that is transported at a freight rate for commercial gain. ''Cargo'' was originally a shipload but now covers all types of freight, including transport by rail, van, truck, or intermodal container. The term cargo is also used in case of goods in the cold-chain, because the perishable inventory is always in transit towards a final end-use, even when it is held in cold storage or other similar climate-controlled facility. The term freight is commonly used to describe the movements of flows of goods being transported by any mode of transportation. Multi-modal container units, designed as reusable carriers to facilitate unit load handling of the goods contained, are also referred to as cargo, especially by shipping lines and logistics operators. Similarly, aircraft ULD boxes are also documented as cargo, with an associated packing list of the items contained within. When empty conta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Towed Pinger Locator
A towed pinger locator is a water-borne device used to locate the sonar "ping" from the underwater locator beacon which is fitted to the Cockpit Voice Recorders and Flight Data Recorders installed in commercial airliners. They can locate pingers at depths of up to underwater. The locator is mounted in a hydrodynamic shell, or "tow fish", connected by winch behind a surface vessel across the search area. The locator listens for the sound emanating from the beacon or "pinger". Once located, the beacon and its attached recorders can be retrieved by divers, submersibles or remotely operated vehicle (ROV), depending on depth. A model currently used by the United States Navy is the TPL-25, which has a weight of and a length of ; it is generally towed at . Most beacons transmit a pulse once a second at 37.5 kHz. The hydrophone must be positioned below the thermocline layer which reflects sounds, either back to the surface or back to the ocean floor. Since the pinger signal is r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Underwater Welding
Hyperbaric welding is the process of welding at elevated pressures, normally underwater. Hyperbaric welding can either take place ''wet'' in the water itself or ''dry'' inside a specially constructed positive pressure enclosure and hence a dry environment. It is predominantly referred to as "hyperbaric welding" when used in a dry environment, and "underwater welding" when in a wet environment. The applications of hyperbaric welding are diverse—it is often used to repair ships, offshore oil platforms, and pipelines. Steel is the most common material welded. Dry welding is used in preference to wet underwater welding when high quality welds are required because of the increased control over conditions which can be maintained, such as through application of prior and post weld heat treatments. This improved environmental control leads directly to improved process performance and a generally much higher quality weld than a comparative wet weld. Thus, when a very high qual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Underwater Photography
Underwater photography is the process of taking photographs while under water. It is usually done while scuba diving, but can be done while diving on surface supply, snorkeling, swimming, from a submersible or remotely operated underwater vehicle, or from automated cameras lowered from the surface. Underwater photography can also be categorised as an art form and a method for recording data. Successful underwater imaging is usually done with specialized equipment and techniques. However, it offers exciting and rare photographic opportunities. Animals such as fish and marine mammals are common subjects, but photographers also pursue shipwrecks, submerged cave systems, underwater "landscapes", invertebrates, seaweeds, geological features, and portraits of fellow divers. Equipment Some cameras are made for use underwater, including modern waterproof digital cameras. The first amphibious camera was the Calypso, reintroduced as the Nikonos in 1963. The Nikonos range was de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Underwater Inspection
Underwater work is work done underwater, generally by divers during diving operations, but includes work done underwater by remotely operated vehicles and crewed submersibles. Skills commonly used by all professional diving occupations Underwater navigation *Pilotage involves navigation by naturally observable landmarks and phenomena, such as sunlight, water movement, bottom composition (for example, sand ripples run parallel to the direction of the wave front, which tends to run parallel to the shore), bottom contour and noise. Although natural navigation is taught on courses, developing the skills is generally more a matter of experience. *Compass navigation is a matter of training, practice and familiarity with the use of underwater compasses, combined with various techniques for reckoning distance underwater, including kick cycles (one complete upward and downward sweep of a kick), time, and occasionally by actual measurement, which may involve the length of umbilical deploye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shoring
Shoring is the process of temporarily supporting a building, vessel, structure, or trench with shores (props) when in danger of collapse or during repairs or alterations. ''Shoring'' comes from ''shore'', a timber or metal prop. Shoring may be vertical, angled, or horizontal. Methods Buildings Raking shores In this method, inclined members called rakers are used to give temporary lateral support to an unsafe wall. One or more timbers slope between the face of the structure to be supported and the ground. The most effective support is given if the raker meets the wall at an angle of 60 to 70 degrees. A wall-plate is typically used to increase the area of support. Foundations Shoring is commonly used when installing the foundation of a building. A shoring system such as piles and lagging or shotcrete will support the surrounding loads until the underground levels of the building are constructed. Commonly used shoring equipment includes post shores, shoring beams, and timber jack ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rigging (industrial)
A rigger is a skilled tradesperson who specializes in the assistance of manual mechanical advantage device comprising pulley, block and tackle or motorised such as a crane or derrick or chain hoists (chain fall) or capstan winch. Etymology The term comes from the days of sailing ships, when a rigger was a person who worked with rigging, that is, ropes for hoisting the sails. Sailors could put their rope skills to work in lifting and hauling. In an era before mechanical haulage and cranes, ropes, pulleys and muscle power were all that was available to move heavy objects. A specialized subset are telecommunication riggers, entertainment industry riggers. In time, rigging became a trade in itself, giving rise to modern usages with some original terminology remaining, with its roots all but forgotten. Description Riggers attach loads of equipment to cranes or structures using shackles, cables, chains, clamps or straps, employing pulleys, winches, lifts or chain hoists (aka cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxy-arc Cutting
Underwater cutting and welding are metalworking techniques used by underwater divers in underwater construction, marine salvage and clearance diving applications. Most Hyperbaric welding, underwater welding is direct current wet stick welding, and most underwater metal cutting is immersed oxygen-arc and shielded metal-arc cutting, though other technologies are available and sometimes used. These processes are mostly applied to steel structures as that is the most common arc-weldable material used in the underwater environment. Scope Oxygen arc cutting and arc welding underwater requires greater skill and stamina than working in a dry and stable environment. The underwater environment imposes several limitations and restrictions on both the equipment and the operator, and the restriction of short bottom times at greater depths for surface-oriented divers makes efficient working important to getting the job done in a reasonable time. The diving equipment encumbers the diver, water ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explosive Fastening
A powder-actuated tool (PAT, often generically called a Hilti gun or a Ramset gun after their manufacturing companies) is a type of nail gun used in construction and manufacturing to join materials to hard substrates such as steel and concrete. Known as ''direct fastening'' or ''explosive fastening'', this technology is powered by a controlled explosion of a small chemical propellant charge, similar to the process that discharges a firearm. Features Powder-actuated tools are often used because of their speed of operation, compared to other processes such as drilling and then installing a threaded fastener. They can more easily be used in narrow or awkward locations, such as installing steel suspension clips into an overhead concrete ceiling. Powder-actuated tools are powered by small explosive cartridges, which are triggered when a firing pin strikes a primer, a sensitive explosive charge in the base of the cartridge. The primer ignites the main charge of powder, which bur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explosive Demolition
In the controlled demolition industry, building implosion is the strategic placing of explosive material and timing of its detonation so that a structure collapses on itself in a matter of seconds, minimizing the physical damage to its immediate surroundings. Despite its terminology, building implosion also includes the controlled demolition of other structures, such as bridges, smokestacks, towers, and tunnels. Building implosion, which reduces to seconds a process which could take months or years to achieve by other methods, typically occurs in urban areas and often involves large landmark structures. The actual use of the term "implosion" to refer to the destruction of a building is a misnomer. This had been stated of the destruction of 1515 Tower in West Palm Beach, Florida. "What happens is, you use explosive materials in critical structural connections to allow gravity to bring it down." Terminology The term ''building implosion'' can be misleading to laymen: The t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tremie
A tremie is a watertight pipe, usually of about 250 mm inside diameter (150 to 300 mm), with a conical hopper at its upper end above the water level. It may have a loose plug or a valve at the bottom end. A tremie is used to pour concrete underwater in a way that avoids washout of cement from the mix due to turbulent water contact with the concrete while it is flowing. This produces a more reliable strength of the product. Common applications include the following. *Caissons, which are the foundations of bridges, among other things, that span bodies of water. * Pilings. * Monitoring wells. Builders use tremie methods for materials other than concrete, and for industries other than construction. For example, bentonite slurries for monitoring wells are often emplaced via tremie pipe. Function The tremie is often supported by a working platform above the water level. The pipe is made up of short sections commonly joined by screw thread with O-ring seal so that the length can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lifting Bag
A lifting bag is an item of diving equipment consisting of a robust and air-tight bag with straps, which is used to lift heavy objects underwater by means of the bag's buoyancy. The heavy object can either be moved horizontally underwater by the diver or sent unaccompanied to the surface. Lift bag appropriate capacity should match the task at hand. If the lift bag is grossly oversized a runaway or otherwise out of control ascent may result. Commercially available lifting bags may incorporate dump valves to allow the operator to control the buoyancy during ascent, but this is a hazardous operation with high risk of entanglement in an uncontrolled lift or sinking. If a single bag is insufficient, multiple bags may be used, and should be distributed to suit the load. There are also lifting bags used on land as short lift jacks for lifting cars or heavy loads or lifting bags which are used in machines as a type of pneumatic actuator which provides load over a large area. These lift ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
