<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
       
<S>                             <C>                     <C>                     <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   3-MOS                   9-MOS                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1998             DEC-31-1997             DEC-31-1998             DEC-31-1997
<PERIOD-START>                             JUL-01-1998             JUL-01-1997             JAN-01-1998             JAN-01-1997
<PERIOD-END>                               SEP-30-1998             SEP-30-1997             SEP-30-1998             SEP-30-1997
<CASH>                                         426,016                 264,247                       0                       0
<SECURITIES>                                         0                       0                       0                       0
<RECEIVABLES>                                2,665,565               3,558,557                       0                       0
<ALLOWANCES>                                         0                       0                       0                       0
<INVENTORY>                                  3,502,269               3,024,597                       0                       0
<CURRENT-ASSETS>                             6,732,048               6,935,442                       0                       0
<PP&E>                                      17,607,303              17,234,988                       0                       0
<DEPRECIATION>                               5,994,551               5,205,058                       0                       0
<TOTAL-ASSETS>                              21,081,831              21,798,022                       0                       0
<CURRENT-LIABILITIES>                        6,721,101               7,333,308                       0                       0
<BONDS>                                      4,220,796               4,732,167                       0                       0
<PREFERRED-MANDATORY>                                0                       0                       0                       0
<PREFERRED>                                          0                       0                       0                       0
<COMMON>                                             0                       0                       0                       0
<OTHER-SE>                                  10,139,934               9,732,547                       0                       0
<TOTAL-LIABILITY-AND-EQUITY>                21,081,831              21,798,022                       0                       0
<SALES>                                     15,317,692              16,314,380              47,415,371              49,320,481
<TOTAL-REVENUES>                            15,378,469              16,380,137              47,652,134              49,501,848
<CGS>                                       13,848,639              14,988,485              43,735,823              45,455,455
<TOTAL-COSTS>                               14,997,052              16,152,385              47,046,753              48,832,213
<OTHER-EXPENSES>                                     0                       0                       0                       0
<LOSS-PROVISION>                                     0                       0                       0                       0
<INTEREST-EXPENSE>                             170,783                 178,894                 518,172                 550,850
<INCOME-PRETAX>                                      0                       0                       0                       0
<INCOME-TAX>                                         0                       0                       0                       0
<INCOME-CONTINUING>                                  0                       0                       0                       0
<DISCONTINUED>                                       0                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0                       0
<CHANGES>                                            0                       0                       0                       0
<NET-INCOME>                                   381,417                 250,843                 605,381                 692,726
<EPS-PRIMARY>                                        0                       0                       0                       0
<EPS-DILUTED>                                        0                       0                       0                       0
        

</TABLE>