STEEL COILS LOADING – ITS CHALLENGES AND WAYS TO OVERCOME
Mr. Spiros Malliaroudakis
(Founder & Managing Director, S.A. Malliaroudakis Maritime (UK) Ltd)The loads derived from steel coils loading are very concentrated, leading to higher stresses in the double bottom than would be expected. Calculation of steel coils loading conditions, which reflect actual loading is essential to maintain the required level of safety. Loading manuals of many ships used in the steel trade that carry coils, contain limited information: either
- The Max. Tank Top Strength (MT/m2) for uniform loading which however is not advisable criterion for Steel Coils Loading.
- In the cases where there is some information from the Builders in the Loading Manual, this is usually the bare minimum, e.g. Covers only the case of 2 Tiers of 15t coils, supported by 3 rows of dunnage.
Weight Distribution Example for 1.5 Tier of 15tons Coils
Weight of the top coil is shared equally between the coils lied on Tank Top or 22.5tons Steel Coils Weight
(Average of the Stack)Concerning the loading of mixed weight / size of coils in each row and/or tier, the involved checks for Steel Coils Loading shall be performed in two levels at first from local strength aspect taking into consideration the Double Bottom Structure & secondly from complete ship loading aspect through specialized Loading Programs covering Longitudinal Strength, Trim, Draughts, Stability, Hold Flooding URS17 etc.) using sophisticated tools with printout, as the one indicated below. Therefore, provided that the lowest/first tier of Steel Coils is the one that matters in terms of local strength, the Ship Operator usually checks the entire stack of Coils based on the Dimensions of the lowest/first tier Coil (Length & Diameter), using as Coil Weight the average of the stack. Attention should be drawn to the applicable Common Structural Rules that apply officially taking into consideration one type of Coil for the entire .
Specialist software available for pre-stow plan assessment with steel products
used in conjunction with the ship’s loading instrumentIn case of multiple types of Coils, it is, usually, sufficient for Ship Operator to randomly check the heaviest/shortest coil to arrive at safe operational day-to-day decisions. Following this check (Local Strength Aspects), the Ship Operator may proceed with the entire Pre-Stow Plan check as General Cargo using the vessel’s approved Loading Program. When loaded in a ship’s hold, steel coils are placed on dunnage. Dunnage has two functions, to spread the steel’s load uniformly in relation to the ship’s structure and to provide frictional resistance. One inch thick softwood dunnage is often used with steel coils. Dunnage can be a mixture of imperial and metric measurements, with 8 inch by 1 inch planks used with steel coils. 60mm by 80mm is used with steel plate and bars, and 6 inch by 4 inch is used with heavy steel. Last but not least, compliance with stowage, securing and lashing principles should be, always, assured. To conclude with, when carrying steel products by sea, it is essential to ensure that neither the steel nor the ship suﬀers damage. Its weight presents substantial challenges with overstresses, stowage and securing. The ship must be fit with the appropriate tools to check receivability of the cargo and the safety best practices of stowage, securing and lashing plans.
Mr. Spiros Malliaroudakis
Founder & Managing Director, S.A. Malliaroudakis Maritime (UK) Ltd