000			00834nam a2200157 4500
001			0000001741
008			110923
040			_aJMGHQ
090	0	0	_a628.1 _bDUC
245	0	4	_aThe ductile iron pipe _b(its superior characteristics and practicability)
260			_c1984
300			_a8 p. _bill. _c30 cm
520			_aIt is proved that gray cast iron has high resistance to corrosion and is moulded easily, but it lacks i strenght. Steel, on the other hand, is strong but its resistance to corrosion is not enough. So, it had been a long-cherised hope that there would be another material possessing both the advantages of gray cast iron and steel, until the year of 1949 when discovered the method to make the graphite in the cast iron spheroidal by adding magnesium to the molten iron.
650		0	_aCast-iron pipe
650		0	_aWater-pipe
999			_c23080 _d23080