Loading arm

A loading arm permits the transfer of liquid or liquefied gas from one tank to another through an articulated pipe system consisting of rigid piping and swivel joints to obtain flexibility.

Transfer to or from a truck transported tank or rail transported tank requires a Top Loading Arm or a Bottom Loading Arm. Transfer to or from a ship or barge requires a marine loading arm.

Both types of loading arms are typically made of 3 pipes – 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 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 cylinder.

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

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Wikipedia