Two savings and loan associations are in danger of failing and some others stand to lose large amounts of money because they had uninsured deposits in the collapsed Penn Square National Bank of Oklahoma City, congressional investigators disclosed yesterday.

Federal Home Loan Bank Board Chairman Richard T. Pratt told a House subcommittee that one S&L was "insolvent" and another "severely impaired." Pratt requested that this information be kept confidential, as well as the fact that "a number of others have been weakened to varying degrees," in a letter to Rep. Benjamin Rosenthal (D-N.Y.), chairman of the Commerce consumer and monetary affairs subcommittee.

The bank board would not say whether the threatened associations would be merged with other, healthy ones to protect investors because such actions are not announced in advance. A bank board spokesman said yesterday he "would not discuss Penn Square in any manner whatsoever."

Penn Square failed July 5 as the result of loans that went bad when oil prices declined. When it was closed by the Comptroller of the Currency and taken over by the Federal Deposit Insurance Corp., Penn Square had uninsured deposits totaling about $190 million, and, according to Pratt's letter, 16 savings and loan institutions had accounted for $16.7 million of that amount.

Seven of those had uninsured deposits that exceeded 10 percent of their worth, and one S&L had $5.9 million of uninsured deposits.

None of the 16 was named in the letter. "We believe that it is necessary to keep the identity of these associations confidential in order to avoid the additional financial strains that could result from public disclosure of their condition," Pratt told Rosenthal. By contrast, the names of credit unions that had $106.3 million in uninsured deposits were given to Rosenthal's subcommittee by the National Credit Union Administration. None of the credit unions is expected to fail as a result of Penn Square losses.

In recounting the exchange of information among regulators prior to the bank's failure, Pratt's letter says that the Office of the Comptroller of the Currency reported 24 savings and loans had uninsured deposits. The comptroller's office was unable yesterday to explain the discrepancy between its figure and the 16 mentioned by the bank board.

The regulator said warnings had been issued to eight S&Ls. Bank board regulations stipulate that no more than one quarter of one percent of the S&L's deposits or net worth shall be invested in any one bank. (Net worth equals assets minus liabilities.) The record shows that one S&L with just $648,000 in net worth had uninsured deposits of $5.9 million, or 911 percent. Another had $2.8 million in uninsured deposits, or $972,000 of its net worth, a ratio of 288 percent.

In response to a question asking whether the bank board knew what was going on, Pratt replied that regulators generally are not required to report excessive or unusual investments in uninsured deposits. Moreover, the board has no regulations concerning S&Ls' dealings with money brokers in placing funds in other financial institutions.

Money brokers played a big role in getting credit unions and savings and loans to place millions of dollars of uninsured deposits in Penn Square in exchange for getting a few extra points' interest.

Three large banks that bought loans from Penn Square have had to write off hundreds of millions of dollars because of those loans, and all suffered operating losses for the second quarter. Those banks are Chase Manhattan, Continental Illinois and Seattle First National.

In addition to bad loans, Penn Square had a very large number--489--of overdrawn accounts, according to the Tulsa Tribune. The Oklahoma newspaper reported Wednesday that the bank had $11.8 million in overdrafts, or 11 times the amount considered normal by the FDIC for a bank of its size. The largest amount was $1.7 million, overdue for 29 days in June.