Ballast tank and Materials of construction

While steel and concrete remain among the most popular storage tank options, glass-reinforced plastic,thermoplastic and polyethylene tanks are gaining in popularity.They have lower construction costs and higher chemical resistance, making them especially suitable for the storage of specialty chemicals.There are several relevant standards such as British Standard 4994 (1989), DVS (German Welding Society) 2205 and ASME (American Society of Mechanical Engineers) RTP-1 which give recommendations on wall thickness, quality control procedures, testing Procedures, certification, manufacturing and design criteria for the final product.

Tank failure

Storage tanks have suffered numerous catastrophic failures, the most notorious of which occurred on January 14, 1919 in Boston, Massachusetts, USA.The large storage tank had only been filled eight times when it malfunctioned, and the resulting wave of molasses killed 21 people nearby.The Boston Molasses Disaster was the result of poor design and construction, with walls that were too thin to withstand the repeated loads of their contents.The tank was not flood tested before use and the riveting was poor.The tank's owner, American Industrial Alcohol, paid $300,000 (nearly $4 million in 2012) to victims or their relatives.

• Since then, there have been many other accidents with tanks, often due to faulty welding or substandard steel.The new invention solves at least some of the more common problems surrounding tank seals.However, surprisingly,storage tanks also present another problem when they are empty.If they were ever used to hold petroleum or petroleum products such as gasoline,      the air in the tanks can be highly explosive because the space is filled with hydrocarbons.If a new welding operation is started, then sparks can easily ignite the contents, with disastrous results for the welder.The problem is similar to void spaces on tankers, which now require the use of an inert gas blanket to prevent the residue from creating an explosive atmosphere.

  Etymology 

• The word "tank" originally meant "artificial lake" and is of Indian origin,possibly through the Portuguese word tanque.It may have some connection to:

• Some Hindi words like "tak" or "tank", meaning "reservoir".In Sanskrit, a cistern or reservoir is called tadaka.The Gujarati word talao means "artificial lake".These uses of the word were incorporated into English.Arabic verb istanqa`a اِسْتونْوَعَ = “It [ie some liquid] gathers and becomes stagnant".

Ballast tank

A ballast tank is a compartment in a boat, steamship, or other floating structure designed to contain water, used as ballast, to provide hydrostatic stability to the vessel, to reduce or control buoyancy, as in a submarine, to correct trim Either lean to provide a more even load distribution along the hull to reduce structural heaving or sagging stresses, or to increase the draft, as in semi-submersibles or platforms or SWATH, to improve seakeeping.Using water in tanks made it easier to adjust the weight than the stone or iron ballast used in older boats, and the crew could easily reduce the draft of the ship by temporarily pumping out the ballast when the boat entered shallower waters. Airships use ballast tanks primarily for buoyancy control and trimming.

Ship

Ballast is used on surface vessels to alter draft, trim, list and stability.It can also be used to modify structural load distributions, typically longitudinal load distributions that affect homing and sagging stresses.It can also be used to change the moment of inertia affecting course motion. International agreements under the Convention for the Safety of Life at Sea (SOLAS) require cargo and passenger ships to be built to withstand certain types of damage.This standard specifies the division of compartments within containers, and the subdivision of these compartments.These international agreements depend on the signatory countries to enforce the rules in their waters and on ships entitled to fly their flags. Ballasts are available to compensate for loss of stability due to flooding of certain compartments.Ballast water is generally water in which the ship floats when ballasted, such as sea water, and is pumped into ballast tanks.Depending on the type of vessel, the tanks can be double bottom (spanning the beam), wing tanks (in the outboard area from keel to deck) or funnel tanks (in the upper corner part between the hull and main deck).These pressure The load compartment is connected to a pump that pumps water in or out.Crews fill these tanks to increase the ship's weight and improve the ship's stability when it is not carrying cargo.In extreme conditions, crews may pump ballast water into dedicated cargo holds to add extra weight in bad weather or to pass over low bridges.