
    486 A.2d 520
    LUU VAN VU and Tuyet Vu, husband and wife v. CLEARFIELD MACHINE COMPANY and S.R. Vanderbeck and S.R. Vanderbeck & Sons, Inc. and Jeffrey Manufacturing Co. and Empire Steel Castings, Inc. Appeal of CLEARFIELD MACHINE COMPANY.
    Superior Court of Pennsylvania.
    Submitted March 27, 1984.
    Filed Jan. 4, 1985.
    
      James M. Marsh, Philadelphia, for Clearfield, appellant.
    Stephen M. Feldman, Philadelphia, for Vu, appellees.
    Edwin L. Scherlis, Philadelphia, for Vanderbeck, appel-lees.
    Robert I. Cottom, Reading, for Jeffrey, appellee.
    William C. Steppacher, Dunmore, for Empire, appellee.
    Before BROSKY, WIEAND and McEWEN, JJ.
   PER CURIAM:

The order dismissing the joinder of Empire Steel Castings, Inc., plaintiffs employer, as a party defendant is affirmed. Heckendorn v. Consolidated Rail Corp., 502 Pa. 101, 465 A.2d 609 (1983). 
      
      . The constitutionality of Section 303 of the Workers’ Compensation Act was neither raised nor considered in the trial court and is not properly before this Court on appeal. It may be observed, however, that the constitutionality of this section was upheld by the Supreme Court in Tsarnas v. Jones & Laughlin Steel, 488 Pa. 513, 412 A.2d 1094 (1980). See also: Eisel v. U.S. Slicing Machine Co., 488 Pa. 192, 412 A.2d 138 (1980).
     