* Q4 adj EPS $3.35 vs est $2.47
* Q4 rev $4.75 bln vs est $4.25 bln
* Ships 71 mln drives in Q4
* Shares up 20 percent in after-market trade (Adds conference call details, first-quarter outlook)
July 25 (Reuters) - Western Digital Corp trounced lofty Wall Street expectations on record sales, and the hard disk drive (HDD) maker is banking on the enterprise market to help maintain its high margins.
Western Digital shares jumped 20 percent in after-market trade to $38.77. They had closed at $32.47 on Wednesday. Shares of rival Seagate Technology Plc also rose 12 percent after-market.
Prices of hard-drives zoomed in the aftermath of the Thai floods last year that cramped capacity. But even as production returns to normal levels, Western Digital and Seagate have maintained their price premiums.
Western Digital said it expects to maintain its high-gross margins for the next year on higher sales to businesses and data center operators.
The company, which posted gross margins of 31.8 percent in the fourth quarter, said it sees margins easing to 30 percent in the current quarter. That is still much higher than the 20 percent gross margin range Wes tern Digital and Sea gate com manded before the Thai floods.
Western Digital projected a first-quarter profit of $2.45 to $2.55 per share on revenue of $4.2 billion to $4.3 billion.
Analysts on average were looking for $2.50 per share profit on $4.45 billion in revenue, according to Thomson Reuters I/B/E/S.
"Western Digital can deliver non-GAAP earnings per share of $10 in fiscal 2013," Chief Executive John Coyne said on a post-earnings call with analysts.
The company, which along with Seagate dominates the HDD market, shipped a total of 71 million hard drives in the quarter.
Profit more than quadrupled to $745 million, or $2.87 per share.
Excluding items, it earned $3.35 per share.
Revenue during the three-month period more than doubled to $4.75 billion.
Analysts on average had expected earnings of $2.47 per share on $4.25 billion in revenue. (Reporting by Himank Sharma, Editing by Anil D'Silva and Sriraj Kalluvila)