Regularization of service in psu now working on contract basic

Dear sir, We are about 500 peoples working in railway PSU our recruitment was through all India test basic and followed by interview, our work of nature is permanent but we are not in regular cadre we are as contract employee of company. some of us are working in this company is more than 9 years so can we go to court for regularization of our service. our contract is being renew each year. kindly give advice on that