The union, along with Teamsters Local 107, failed to sign the agreement by a May 5 deadline set by the Convention Center board.
The two unions contend they were misled about the deadline. Convention Center management is adamant there was no misunderstanding.
The result is the two unions have lost their positions at the Convention Center and work that once went to their members is to be divided among those unions that agreed to the new work rules - Laborers Local 332, Electrical Workers Local 98, Stagehands Local 8, and Iron Workers 405.
"The signatory unions will handle the extra workload cost-effectively and in the most hospitable manner possible," John Dougherty, business manager for the electrical workers, said in a statement.
The work-rules contract, known as the Customer Satisfaction Agreement, is the Convention Center's attempt to make the facility more attractive to trade shows. The center, despite a $780 million expansion, has failed to live up to expectations. Its management has placed the blame on "antiquated work rules" that unnecessarily drove up costs for exhibitors.
The agreement ratified Tuesday changes work rules at the center to give exhibitors more flexibility in terms of putting up booths and displays without union workers. It also gives Convention Center management more control over which union workers are assigned.
The Carpenters and Teamsters made a belated attempt to rectify matters Friday, when they unilaterally signed copies of the agreement. It was too late, according to John McNichol, the Convention Center chief executive officer. The agreement, as a signed contract, can be reopened only by agreement of all who signed, McNichol said, including the four other unions.
The center on Monday is hosting the BIO World Congress on Industrial Biotechnology. About 1,100 people are expected.
The Convention Center and Police Department have been preparing in the event of trouble.
"We are taking steps to ensure the safety of everyone who will be at the center," center spokesman Pete Peterson said Saturday.
The Police Department Division of Homeland Security and Civil Affairs has been monitoring the situation at the center, police spokesman Lt. John Stanford said.
"I'm sure they have a game plan in place," he said.
Inquirer staff writers Joseph DiStefano and Claudia Vargas contributed to this article.