The Sensex opened with a positive gap of 32 points at 13,222, and slipped into the negative zone to a low of 13,174.The index is now up 46 points at 13,235.Tata Steel has surged nearly 3% to Rs 510. Hindalco, Satyam and Cipla are the other prominent gainers.HDFC has slipped 1.4% to Rs 1,586.
