bids are invited for operation and maintenance of other machines and plants - annual rate contract for heat exchanger re-tubing job at nrl site-non rta - item 10- recond old tube bundle tube insertion , operation and maintenance of other machines and plants - item 20-non rta-expanding tubes after retubing , operation and maintenance of other machines and plants - item 30-non rta-strength welding including light expansi , operation and maintenance of other machines and plants - item 40-non rta-mob demob charge per occ for normal job , operation and maintenance of other machines and plants - item 50-non rta-mob demob charge per occ for emmergency , operation and maintenance of other machines and plants - annual rate contract for heat exchanger re-tubing job at nrl site- rta-item 60- recond old tube bundle tube insertion , operation and maintenance of other machines and plants - item 70- rta- expanding tubes after retubing , operation and maintenance of other machines and plants - item 80- rta- strength welding including light expansion , operation and maintenance of other machines and plants - item 90- rta- bending tubes to req dimensions for u- t , operation and maintenance of other machines and plants - item 100- rta- mob demob charge per occ for normal job