SIPTU members at gas network infrastructure company, GMC Civil and Mechanical Engineering, will begin nationwide strike action next week.
The union has accused the company of failing to implement recommendations on pay and conditions which it says it had agreed with management.
SIPTU has also accused GMC of outsourcing union members' work.
The union said its members in GMC have not received a pay increase since 2019.
"Our members overwhelmingly backed the decision for strike action by a margin of 97%," said SIPTU Public Administration and Community Division Organiser Adrian Kane.
"SIPTU members are determined that the proposals which have been agreed on pay are the only basis for the resolution of this dispute," Mr Kane said.
As part of the strike on Wednesday, pickets will be placed at locations in Dublin, Carlow, Cork and Limerick.
GMC Civil and Mechanical Engineering is contracted by Gas Networks Ireland for the installation, maintenance and provision of emergency response on Gas Networks Ireland infrastructure.
GMC said it was disappointed with the notice of strike action as it had engaged constructively with the employees and their representatives who transferred to the company on 1 August, 2021.
"The company has not frustrated any resolution of the pay dispute and have amicably resolved pay and conditions for the majority of employees since the transfer date," the company said.
"The matter has been referred to the WRC and a conciliation meeting has been arranged at the WRC between the company and SIPTU in the week after the commencement of the strike," GMC said.
The company added that it has always respected the machinery of the state.
GMC said it is a member of the Construction Industry Federation (CIF) and that all employees are paid in accordance with the Construction Sectoral Employment Order (SEO).
