The U.S. Bankruptcy Court in Wilmington, Del., yesterday announced the forthcoming retirement of Judge Peter J. Walsh, effective Jan. 1. Calling Judge Walsh “irreplaceable,” the announcement nevertheless says that court officials are looking for a new judge to take his spot on the bench that has consistently presided over some of the biggest corporate restructurings in recent decades. Judge Walsh first joined the bankruptcy bench in 1993. For years he was one of only two sitting bankruptcy judges in Delaware, first with now-retired Judge Helen Balick and then with current Judge Mary Walrath, leaving him with a heavy caseload. He served as chief judge from September 1998 to September 2003.