Industrial Application of Ductile Iron Pipes at RRVUNL Thermal Power Plant, Chhabra, Rajasthan
Rajasthan Rajya Vidyut Utpadan Nigam Limited (RRVUNL) embarked on the development of a 2×660 MW coal-based supercritical thermal power project at Chhabra, Baran district, Rajasthan. The project envisaged the commissioning of the pipeline for the river water system in Contingency Plan, Stage I and Stage II, for laying and jointing of pipeline. What makes this project most interesting is that this was the first experience of RRVUNL with ductile iron pipes.
Project development
The job was awarded to the contractor in May 2015. The job of the river water system at RRVUNL, Chhabra, was full of technical challenges and also included obtaining right of use for pipelines. The contractor did that on a timely basis because they had received timely cooperation from the local inhabitants and population.
The work consisted of an intake well, piping, reservoirs, pump houses and substations. initially, the project was designed with mild steel pipes. Thereafter, a detailed engineering study was undertaken with ductile iron pipes, and a techno-economic comparison between ductile iron and mild steel pipes showed that the option with ductile iron pipes is more viable.
All piping works in this project use ductile iron. Out of Rs 497 crore, Rs 300 crore is the piping value. Ductile iron pipes with diameters of 700 mm, 900 mm and 1,000 mm have been used in this project. The maximum test pressure was 18 kg per cm2 and the test pressure at the site was maintained in all the sectional tests for 24 hours without any leakage.
An example of smooth operation
There was no problem in stabilising the DI pipeline during sectional hydro-testing at 18 kg per cm2 for 24 hours. There were no joint leakages. The experience with the DI pipeline has been smooth all along.
Conclusion
The RRVUNL Chhabra project showcases an example of state-of-the-art design and execution. The contractor has laid hundreds of kilometres of pipeline in the past 25 years and principally the pipe material that they have installed was mild steel. This was the first time the contractor laid ductile iron pipes. The basic benefits that they found while installing ductile iron pipes are their fast rate of laying and easy to join, leakproof joints. Ductile iron pipes because of their flexible joints required very few fittings and specials and they could be laid as per the profile of the terrain.
