A loading arm permits the transfer of

liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, an ...

or liquefied gas from one tank to another through an articulated pipe system consisting of rigid piping and

swivel joint A swivel is a connection that allows the connected object, such as a gun, chair, swivel caster, or an anchor rode to rotate horizontally or vertically. Swivel designs A common design for a swivel is a cylindrical rod that can turn freely with ...

s to obtain flexibility. Transfer to or from a

truck A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame constructi ...

transported tank or

rail transport Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in Track (rail transport), tracks. In contrast to road transport, where the ...

ed tank requires a Top Loading Arm or a Bottom Loading Arm. Transfer to or from a

ship A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguishe ...

barge Barge nowadays generally refers to a flat-bottomed inland waterway vessel which does not have its own means of mechanical propulsion. The first modern barges were pulled by tugs, but nowadays most are pushed by pusher boats, or other vessels. ...

requires a

marine loading arm A marine loading arm, also known as a mechanical loading arm, loading arm, or MLA is a mechanical arm consisting of articulated steel pipes that connect a tankship such as an oil tanker or chemical tanker to a cargo terminal. Genericized trademark ...

Top and Bottom loading arm

* ''General feature of Top and Bottom loading arms'' Top Loading Arm

Both types of loading arms are typically made of 3

pipe Pipe(s), PIPE(S) or piping may refer to: Objects * Pipe (fluid conveyance), a hollow cylinder following certain dimension rules ** Piping, the use of pipes in industry * Smoking pipe ** Tobacco pipe * Half-pipe and quarter pipe, semi-circul ...

s – respectively called inner arm, outer arm and drop pipe. The size can be from 2” to 6”. These 3 pipes are connected by swivel joints. Swivel joints are required to provide the flexibility needed. The loading arm unfolds to get the required

working envelope {{other uses, Envelope (disambiguation) In mechanical engineering, an envelope is a solid representing all positions which may be occupied by an object during its normal range of motion. Another (jargon) word for this is a "flop". Wheel envelope I ...

to load or unload the tanker, and the reverse is to retract or get a minimal space for parking or storage. Both types of loading arms may be mounted on a column or via a plate to an existing wall. Balancing is needed due to the weight of the steel piping. Balancing of the arm is made by counterweight or by a

spring balance A spring scale, spring balance or newton meter is a type of mechanical force gauge or weighing scale. It consists of a spring fixed at one end with a hook to attach an object at the other. It works in accordance with Hooke's Law, which states ...

cylinder.

Top loading arm

Top loading arms are used to load or unload road or rail tankers. Loading or unloading is done through the manhole on the top of the tanker. Top loading arms can also be used for tight-fill, vapor recovery, marine and other applications when used with specially designed and engineered components, such as vapor plates, tapered hatch plugs, and inflatable hatch seals. Depending on the nature of the product (not dangerous, without any toxic vapors...), the connection may be “open”, this means that the manhole is not sealed. A “Semi-Closed” connection can be made by a cone on the manhole of the tanker. A “Closed” connection is required for all dangerous and toxic products. This connection is made by a

flange A flange is a protruded ridge, lip or rim (wheel), rim, either external or internal, that serves to increase shear strength, strength (as the flange of an iron beam (structure), beam such as an I-beam or a T-beam); for easy attachment/transfer of ...

to the top of the tanker. A cone can be equipped with a vapour hose to prevent the vapors from being released to the atmosphere. Numerous accessories are available to make a loading arm more

ergonomic Human factors and ergonomics (commonly referred to as human factors) is the application of psychological and physiological principles to the engineering and design of products, processes, and systems. Four primary goals of human factors learnin ...

and more effective: press down system, pneumatic up/down system, top level control, safety break valve, purge, drain...etc.

Bottom loading arm

This kind of arm is reserved for the unloading of road/rail tanker from the bottom, at the rear or side. The location of the connection has an influence on the length of the pipes. As an example, a rear connection requires a longer length of arms than for a side connection. The connection of this kind of loading arm can be made by flange, thread or by quick connection coupler such as a Dry Disconnect. There are also a numerous accessories which can be fitted to the Bottom loading arm to make it more ergonomic and more effective as described for the Top loading arm.

Marine loading arm

To load or unload a ship, a hose or loading arm is needed to follow the movement of the ship due to the dynamics of changing draft, changing

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables can ...

wind Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ...

and other factors. A Marine Loading Arm offers a significant improvement over a hose in the transfer of liquids between vessel and shore because It provides an easier and more ergonomic operation, gives longer service life and permits Emergency Release Action without any spillage of product and without any

pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...

. Like the Top and Bottom loading arm, the Marine Loading Arm is a system consisting of rigid piping and swivel joints to obtain flexibility. The OCIMF ( Oil Companies International Marine Forum) and

ASME The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via " continuing ...

have established guidelines for matters of strength calculations, working envelope and accessories. However the design of the loading arm is not included in this guideline and left to the individual

manufacturer Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector of the economy. The term may refer to a ...

. * ''Different design for Marine loading arm'' The

product line Product may refer to: Business * Product (business), an item that serves as a solution to a specific consumer problem. * Product (project management), a deliverable or set of deliverables that contribute to a business solution Mathematics * Prod ...

reposes on a fixed stand post or riser and is connected by an inner and an outer arm – both arms are movable parts. Balancing is needed due to the weight of the steel piping. Balancing of the Marine Loading Arm is done by a rotating counterweight, which is connected to the inner arm and the outer arm via a rigid pantograph. Small loading arms may be manually operated. The bigger ones are hydraulically operated. The product line can be self supported or mounted on an independent support frame. Since the swivels are strong enough to absorb the weights of the product line, the liquid in the arms and the forces of the wind, the marine loading arm can be built as a self-supporting structure. Nowadays marine loading arms can also be built on an independent support frame as is required for LNG and highly corrosive liquids. Recently the design of the marine loading arms has been significantly improved by the

symmetric Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definit ...

design. This new concept offers many advantages such as the equal distribution of forces on the swivel joints under all conditions, less force within the structure, reduces the weight of the loading arm, and permits larger working envelopes without requiring significantly stronger

construction Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and ...

. Since the symmetric design has proven its effectiveness and its reliability. The symmetric design is also applicable to marine loading arms requiring an independent support frame. File:Marine Loading Arm KLEa.jpg , 2 Marine loading arms connected to ship File:Marine Loading Arm KLE.jpg , Marine loading arms connected to ship File:Marine Loading Arm long inboard KLE.jpg , Marine loading arm with long outboard File:Marine Loading Arm from the air KLE.jpg , Marine loading arm connected to ship Air view

References

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Top and Bottom loading arm

Top loading arm

Bottom loading arm

Marine loading arm

References

Further reading