The Performance, Safety and Production Benefits of SPS Structures ...

Other performance characteristics that have beenestablished and quantified include:• Fatigue resistance (S-N curves) of the interface bondand welded connection details specifically developedto join prefabricated SPS plates (refer to FigureA.2(a)).• Salt water and chemical resistance of the elastomercore should it become exposed during the life of thestructure. Figure A.2(b) shows test samples fromone of four test series where sets of 30mm elastomercubes were completely immersed in typical chemicalspecies.• Vibration damping and structural borne noisetransmission Figure A.2(c) illustrates typicaldisplacement attenuation curves for SPS and steelplates subject to a single pulse. The inset pictureillustrates a standard vibration characterisation testconducted at BASF laboratories in Ludwigshafen.• Ballistic resistance limits for stiffened steel and SPSplates (all-steel and bi-metal) subject to standard7.62mm rounds are illustrated in Figure A.2(d). Thesetests were conducted by QINETIQ (formally DERA).FIRE RESISTANCE AND ENGINEERINGSPS has exceptional resistance to fire. It is an extremelyeffective barrier to heat, flame, smoke and toxic gases. Itwill contain a fire and prevent it spreading to adjacentcompartments, greatly limiting the growth of a firethroughout a structure. This has been demonstrated byan extensive series of full-scale deck panel and bulkheadtests, conducted in accordance with IMO (SOLAS)standards at independent fire laboratories. The MaritimeCoastguard Agency (MCA) co-developed the fire safetytest programme and has witnessed SPS fire tests. FigureA.3(a) shows the standard SOLAS stiffened steel deckpanel without structural fire protection. The plate isseverely distorted and the maximum surface temperatureincrease on the unexposed surface is +713ºC. The surfacetemperature on SPS plate with structural fire protection,shown in Figure A.3(b), is +3ºC. The correspondingtemperature on an insulated steel plate was +192ºC.(b) SPS 8-40-8 deck plateFigure A.3 Safety of Life at Sea – Enhanced FireResistanceThe steel face plates present a fully non-combustiblebarrier to a fire that may occur from either side and theelastomer core provides an extremely effective insulatoragainst heat from fires. If an SPS panel is directlyexposed to fire for an extended period then the elastomercore acts as sacrificial layer on the fire side (ablation)and gases from the elastomer surface vent into the fireside through temperature controlled pressure releasevalves. Only the exposed elastomer surface layer isaffected, the remaining elastomer and the elastomer-steelbonded surface on the unexposed surface are unaffected.SPS can provide greater insulation than conventionalarrangements. After the standard 60-minute fire test(945ºC at one hour), the average temperature increase onthe unexposed surface of a SPS 4-25-4 plate withoutstructural fire protection was 96ºC. The correspondingincrease for a SPS 8-40-8 plate was 24ºC. For an A-60barrier, SOLAS requires this increase to be no greaterthan 140ºC. With SPS plates the unexposed surfaceremains cooler longer, extending containment of the fire,and allowing more time for people to escape and firefighters to fight the fire. Based on the experimentalevidence and fire engineering analyses conducted withthe University of Strathclyde, the MCA has submitted thefollowing information papers to the IMO on theperformance and behaviour of SPS when subjected tofire loads.• Equivalence of a New Composite Structural Materialto Steel in Maritime Structures SPS (Sandwich PlateSystem), Maritime Safety Committee 74 th session,2001• Fire Equivalence of SOLAS Chapter II-2 for theSandwich Plate System (SPS), Sub-committee onFire Protection 47 th session, 2002(a) stiffened steel plate15