Remote operations

The most basic subsea satellite is a single Subsea Wellhead with Subsea Tree, connected to a production facility by a series of pipelines and umbilicals. A control module, usually situated on the subsea tree, allows the production platform to remotely operate the subsea facility (i.e. valves, chokes). 

The manifold is typically a tubular steel structure (similar to a template) which is host to a series of remotely operated valves and chokes. It is common for subsea tree control systems to be mounted on the manifold and not on the individual trees. A complex manifold will generally have its own set of dedicated subsea control modules (for controlling manifold valves and monitoring flowline sensors). 

The master control station allows the operator to open and close all the systems remotely operated valves, including tree and manifold valves and downhole safety valve. 

In many applieations, eg. within the nuclear, offshore and subsea fields it has been required to have a small unit, that could be placed unattended, close to the scanning object and operated from a remote operation unit. 

The maximum bubble pressure method is good to a few tenths percent accuracy, does not depend on contact angle (except insofar as to whether the inner or outer radius of the tube is to be used), and requires only an approximate knowledge of the density of the liquid (if twin tubes are used), and the measurements can be made rapidly. The method is also amenable to remote operation and can be used to measure surface tensions of not easily accessible liquids such as molten metals [29]. 

The material of interest is dissolved in a volatile solvent, spread on the surface and allowed to evaporate. As the sweep moves across, compressing the surface, the pressure is measured providing t versus the area per molecule, a. Care must be taken to ensure complete evaporation [1] and the film structure may depend on the nature of the spreading solvent [78]. When the trough area is used to calculate a, one must account for the area due to the meniscus [79]. Barnes and Sharp [80] have introduced a remotely operated barrier drive mechanism for cleaning the water surface while maintaining a closed environment. 

Special safety constraints apply to equipment selection, design, and operation in nuclear reprocessing (269). Equipment should be reHable and capable of remote control and operation for long periods with minimal maintenance. Pulsed columns and remotely operated mixer—settlers are commonly used (270). The control of criticaHty and extensive monitoring of contamination levels must be included in the process design. 

Normal Operation. The designer of a chemical plant must provide an adequate interface between the process and the operating employees. This is usually accompHshed by providing instmments to sense pressures, temperatures, flows, etc, and automatic or remote-operated valves to control the process and utility streams. Alarms and interlock systems provide warnings of process upsets and automatic shutdown for excessive deviations from the desired ranges of control, respectively. Periodic intermption of operations is necessary to ensure that instmments are properly caUbrated and that emergency devices would operate if needed (see Flow measurement Temperaturemeasurement). 

Other considerations are (I) proper ventilation and discharge enclosures, (2) provision for relief of internal explosion, (3) vibration isolation (shock mounts), (4) remote operation of charge and discharge, (5) noise during operation. 

Iligh-voltage controllers which regulate prirnaiv input voltage to the rectifier and wiper transformer and house primary current-limiting protection, meters, and instrumentation are designed for local or remote operation. 

Remotely Operated Shutoff Valves These should be considered for supply lines and other vulnerable pipelines. Excess flowvalves that close vmen flow exceeds a set amount are possible substitutes, but they are not acceptable to some operators. 

Magnetic motor starters are similar in function to manual starters except that thev are solenoid-operated, Thev are available up to 3730 kW (5()()0 hp). One of the main advantages is the convenience of electrical operation. Start-stop push buttons can be located anywhere, lien automatic or remote operation is needed, magnetic starters are essential. 

Installation of internal excess flow or fail-safe remotely operated valves for tanks at locations where piping connects... 

Provide remote operation capability where necessary... 

Where needed and practical, install remote operation to remove operator from hazard zone... 

Seabed trenching from remote-operated vehicles (Figure 7.9)... 

San Diego Gas Electric s system was originally installed as a research project. The intent of the research project was to test the hardware in this application, test the feasibility of operating such a system remotely with no local operators, and to prove the economics. Similar systems had been installed within process plants where operators were present to start and stop the system and monitor its operation. However, this was the first system installed on a natural gas transmission system with completely remote operation. 

Isolation Provide for isolation from upstream and downstream operations. Consider provision of automatic and/or remotely operated isolation. Consider isolation for cleaning needs... 

Following some mtxiifications to a pump, an operator pressed the stop button on the control panel and saw that the pump running light went out hence closed a remotely operated valve in the pump delivery line. Several houi s later the high-temperature alarm on the pump sounded soon afterward there was an explosion in the pump... 

Consider installing remotely operated isolation valves in the biiucnis piping connected to vessels containing large inventories of hot solvents... 

If water has to be drained regularly from liquefied flammable gases or other flashing liquids, and if a spring-loaded valve cannot be used, then a remotely operated emergency isolation valve (see Section 7.2.1) should be installed in the drain line. 

Many fires have been prevented or quickly extinguished by remotely operated emergency isolation valves. We cannot install them in the lines leading to all equipment that might leak. However, we can install them in the lines leading to equipment that, experience shows, is particularly liable to leak (for example, very hot or cold pumps or drain lines, as described in Section 7.1.2) or in lines from which, if a leak did occur, a very large quantity of material, say 50 tons or more, would be spilled (for example, the bottoms pumps or reflux pumps on large distillation columns). 

It would be going too far to say that no one should ever enter a cloud of flammable vapor to isolate a leak. There have been occasions when, by taking a risk for a minute, a man has isolated a leak that would otherwise have spread a long way and probably ignited, perhaps exploded. However, we should try to avoid putting people in such situations by providing remotely operated emergency isolation valves to isolate likely sources of leak. 

New installations should be provided with only one connection below the liquid level, fully welded up to a first remotely operated fire-safe isolation valve located clear of the tank area. 

Remotely operated depressuring valve allows stress on the vessel to be reduced... 

A eondensate pump was started up by remote operation, with both suction and delivery valves closed. The pump disintegrated, bits being scattered over a radius of 20 m. If remote starting must be used, then some form of interlock is needed to prevent similar incidents from occurring. 

Provide remotely operated emergency isolation valves (see Section 7.2.1). 

Remotely operated emergency isolation valves (see Section 7.2.1) should be fitted on filling lines. If the hose breaks for any reason, the flow can be stopped by pressing a button located at a safe distance. Reverse flow from the tank truck or car can be prevented by a check valve. 

A radioactive source was transferred from one container to another by remote operation in a shielded cell. A radiation detector, interlocked with the cell door, prevented anyone from opening the cell door when radiation could be detected inside it. To make sure the interlock was working, an operator tried to open the cell door, by remote control, during a transfer. He found he could open it. He then found that the closing mechanism would not work. Fortunately he had not opened the door very far. 

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