Friday, 9 December 2011

Easy Loading Notation

Vale Beijing is classed with Classification Society Det Norske Veritas (DNV). DNV’s role is to act as the effective industry regulator in checking the structural integrity and construction standards. Using advanced finite-element analysis computer modelling, DNV compares the design against its own structural rules to determine what Class Notation will be assigned to the vessel.

DNV model of a bulk carrier's hull

Class Notation is a shorthand summary of the features incorporated into the design and construction of the vessel. Vale Beijing’s notation is;

1A1 Ore Carrier ESP ES(O) E0 BWM-E(s) IB-3 COAT-PSPC(B) BIS EL-2 TMON NAUTICUS (Newbuilding)

The notation EL (Easy Loading) is a new one developed for large bulk carriers. EL-1 means that each cargo hold must be loaded in two pours of about 50% of the total capacity. This is the current ‘norm’ in the bulk trades, and is done to minimise the bending and shear force stress in the ship’s structure as cargo is poured in and ballast water is pumped out.

EL-2 notation means that the full capacity of the cargo hold can be loaded in a single pour. This reduces the amount of unproductive time at the terminal shifting the ship loader between hatches. In the case of Vale Beijing, that’s 45,000 tonnes of iron ore in each of her 9 hatches at a loading rate of up to 16,000 tonnes per hour.

The Antipodean Mariner doesn’t have the technical knowledge to second guess the structural calculations and algorithms on which DNV assessed the hull girder. The observation is made that this class of vessel are the largest bulk carriers ever built, and Bulk carriers suffer far higher hull stresses than VLCC tankers of a similar sizes due to heavy iron ore being poured into a single hold rather than being spread across multiple tanks. STX and DNV will be poring over the design calculations to ascertain how a brand new ship suffered such a catastrophic structural failure during her first loading.

Follow the link to footage from a local Brazilian TV channel showing Vale Beijing being towed ‘dead ship’ to anchorage in Sao Luis.

The Antipodean Mariner will continue to follow this story and keep the blog updated with any developments.

PS: News from Bloomberg that Vale Beijing has cracking in her hull, ballast tanks and cargo hold - indication to the Antipodean Mariner that the problem is structural failure rather than a fault in a welded seam.


1 comment:

  1. Thanks for the fascinating insight AM – I’m not out of the industry, but have a good knowledge of engineering (even though not on this epic scale) ..... just figured it would be standard practice to load and unload such a long structure reasonably evenly (yes ballast helps). Staggered by the implications of the EL2 standard on such a large structure, ......maybe the engineers figured that just because she was being loaded in a calm port that she wasn’t experiencing dynamic loading while doing EL2, a passing ships wake would pay to that!? Goes without saying they’ll be employing EL1 next time they fill one of these beasts. :/ Thanks again love your blog. PS more on Rena please!