No. 80-1753. January 31, 1983. Rehearing and Rehearing En Banc Denied March 21, 1983. Elliott Moore, Deputy Assoc. Gen. Counsel, Sandra Williams, David Fleischer, N.L.R.B., Washington, D.C., for petitioner. Donald S. Shire, Associate Sol., Barbara E. Kahl, U.S. Dept. of Labor, Washington, D.C., amicus curiae, Secretary of Labor. Eric H. Nelson, Houston, Tex., for intervenor Teamsters Local No. 968. Liddell, Sapp, Zivley, Brown Laboon, W. Robert Brown, Douglas R. Little, Houston, Tex., for respondent