The IACS issued URS21A in June 2011. This regulation is applicable to the steel weathertight hatch cover and coaming of all vessels but bulk carrier,VLOC and combination carrier. And it will work on 1st July,2012.
The new regulation,URS21A is with more complicated technology and various content,is quite different from past ones. In loading evalsssuation,it will include the horizontal wave load,cargo pressure,ship motion,container loading condition,and hull deformation load besides the vertical outdoor design load. In structure strength evalsssuation,it not only inspects various constructional elements,but also needs more complicated details. In yield strength evalsssuation,it requires testing the yield strength of the top plate,base plate,main supporting structure,and stiffeners of hatch cover. This idea comes from CSR BC,which has be improved. To make the evalsssuation much more difficult. In addition,UR S21A also has some requirements in the spare parts,including foundation of hatch cover,sealing material,drainage device,etc.
For the classification society and industrial community,the new requiremnt,method and idea are the most important points in the technology of hatch cover. CCS has done much calculation verification and comparison for the new regulation. On the other aspect,the designers of hatch cover and ships discussed the new regulation and put forward that the second article chapter 2 sections 20 of "Classification Rules of Steel Sea-going Vessel",which is about the hatch cover,will be modified. And it will become effective on 1st July,2012.