P528ORACLE 528 Mon17 Feb C4 1702:24   RHP PAYS £30m FOR  FIRE DETECTION FIRM  Engineering outfit RHP Group is to spend a total of £30m acquiring the fire detection specialist Graviner from its US parent Allegheny International. New shares worth £24.25m are to be placed by Allegheny which will also receive £5.75m direct from RHP as it repays outstanding loans.  Plessey has won a £20m order for radar systems to be fitted to the latest Royal Navy destroyers, aircraft carriers and frigates.  Oil ministers from Algeria, Iran and Libya are meeting in Algiers to discuss the effect of failling oil prices.  City headlines 500 Newsfile 520