The unanimous vote for future action came after a four-hour work stoppage in which more than 200 union members heard updates about negotiations with the company.
Talks between union members and PWCS have seen more than eight months of negotiations.
A spokesman for PWCS said the company was negotiating in good faith with the unions.
The members unanimously voted for a resolution giving the five unions that make up the Single Bargaining Unit authority to consider, over the next two weeks, any action necessary to resolve the dispute.
The single bargaining unit representing workers comprises the Maritime Union of Australia, the Transport Workers Union, the Electrical Trade Union, and the Australian Manufacturing Workers Union.
This may include future work stoppages and bans on overtime and working outside classifications or work-to-rule efforts, according to the Maritime Union of Australia assistant national secretary Ian Bray.
“We are determined to reach an agreement, hopefully through productive discussions with the company. However, we will consider all legal options open to us,” he said.
Any future action also will include a broadening of international support from maritime and mining unions in the 4.5 million member International Transport Workers federation and IndustriALL, which represents 50 million workers in 140 countries, in the mining, energy and manufacturing sectors.