isi marked centrifugally cast ( spun ) ductile iron pressure pipes class k-7 and k-9 for water gas and sewerage , d . i . pipes class k-7 , 100mm class k-7 , 150mm class k-7 , 200mm class k-7 , 250mm class k-7 , 300mm class k-7 , 350mm class k-7 , 400mm class k-7 , 450mm class k-7 , 500mm class k-7 , 600mm class k-7 , 700mm class k-7 , 750mm class k-7 , 800mm class k-7 , 900mm class k-7 , 1000mm class k-7 , 1100mm class k-7 , 1200mm class k-7 , d . i . pipes class k-9 , 100mm class k-9 , 150mm class k-9 , 200mm class k-9 , 250mm class k-9 , 300mm class k-9 , 350mm class k-9 , 400mm class k-9 , 450mm class k-9 , 500mm class k-9 , 600mm class k-9 , 700mm class k-9 , 750mm class k-9 , 800mm class k-9 , 900mm class k-9 , 1000mm class k-9 , 1100mm class k-9 , 1200mm class k-9