10 August 2011

Iron from Shipbreaking!

This refers to a report on 'shipbreaking' that was published recently in a national daily. It was reported that "the iron is of low quality and according to BUET it is unfit for construction of a "solid structure." This vague statement, does not technically specify steel qualities, which could be Ultimate Tensile Strength, Yield Strength or Percentage Elongation; some of the usual criteria that determine steel quality are used for various purposes including ship-building.

As a graduate metallurgical engineer from Ahsanullah Engineering College, the predecessor of BUET and with hands-on experience in steel manufacturing, the only iron I know of -- having and quality control in place for steel making -- is that approved by Lloyd is 'Grade A' steel, that we manufactured in Chittagong Steel Mills. 

The only iron I know of, are pig iron, cast iron and wrought iron; but we never produced these! I do not agree to the broad opinion that was expressed in the report. Steel can be of different qualities; and unless the quality of steel needed for 'solid construction' is not specified as well as the quality of steel rolled from ship's plates of shipbreaking units is known or determined, such comparisons are technically speaking, just "pie in the sky"; and more subjective than objective!

Ships hull and deck plates are made usually from Lloyds Grade A steel. I have forgotten the UTS, Yield Stress and Elongation as I did this work during the days between 1968 and 1973. However, one thing I clearly remember. It is that ships deck and hull plates have to be tested for ductility from usual ambient.

For generalists, it is to be pointed out that the chemical and mechanical properties of ship-building steel retain well beyond half a century. Ships are scrapped for high operating costs, when fuel consumption of the vessel goes high. This fault is usually related to the main engine design, specific fuel consumption and wear and tear of mechanical and electrical components but never for the quality of steel. The ship has a valid registration from Lloyd or other ship classification societies.

Source: The Financial Express, Bangladesh. Reviews & Letters. By Engr. S. A. Mansoor. 4 March 2011

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