Before the first drop of water was allowed to flow through the pipes in the new Dwarka Tunnel, the high-pressure water mist system underwent a kind of ‘medical examination’. After all, the system must respond without any problems and be fully functional in an emergency. As with any check-up, it is better to check one too many rather than one too few times
Endoscope in – X-ray on
An endoscope was used to inspect the weld seams inside the pipes, allowing potential irregularities to be identified early and, if necessary, corrected before the system even reached the construction site. This helped streamline the commissioning process.
In addition, random spot checks were performed using a mobile X-ray device to examine the welds from the outside. The standard was clear: every seam had to be perfect – gapless, tight, and durable.
Stress test – pressure that is otherwise only experienced in an emergency
After checking the connections and installation, the entire system was subjected to a stress test. During the spray test, in accordance with SOLIT and NFPA 750, blind plugs were fitted to each section of the system instead of open nozzles, to prevent water from entering the tunnel.
Each section was then pressurised for two hours at 1.5 times the normal operating pressure.
Engineers and project managers monitored every single connection with a trained eye and the appropriate measuring equipment. The aim was to identify any weak points.
Press fittings used in high-pressure water mist systems undergo thorough testing before approval. As these systems operate at pressures well more than 100 bar, the fittings must prove their leak-tightness and mechanical strength under demanding conditions.
They undergo pressure testing beyond their nominal values to detect leaks or deformations. They are also subjected to cyclical loads to simulate long-term use. Pull-out tests ensure that the pipe sits securely, even under axial load. Additional vibration and corrosion resistance tests are required for use in tunnels. Only fittings that fulfil all relevant performance criteria are approved for installation in safety-critical systems, such as the Dwaraka tunnel.
The diagnosis: 100% leak-proof
The result speaks for itself: no leaks, no weak points. Every seam and every connection withstood the pressure.
The system has therefore been officially tested and approved and is ready for use in an emergency.
In the Dwarka Tunnel, one of the most modern road tunnels in Asia, the system will protect thousands of people every day. They can rest assured that this fire protection system has been thoroughly tested under high pressure. In the event of a fire, the high-pressure water mist system from FOGTEC will guarantee that the impact on the tunnel is minimal and that it can be reopened quickly. This is of immense importance at a critical traffic junction in a metropolis like Delhi.
