NRV Bonnet leakage in a prominent power plant in India
The Problem
In a critical steam-handling section of a prominent power plant in India, a sudden leakage was identified at the bonnet of a 6-inch Non-Return Valve (NRV). The leak was discharging steam and condensate at 8 bar pressure and 180°C temperature, posing serious hazards to nearby equipment, insulation, and most importantly, operational personnel.
The continuous leakage not only threatened to halt a key section of the process unit but was also incurring significant energy losses. Preliminary estimates indicated an hourly steam loss worth several thousand rupees, with risk of progressive damage to nearby components if left unchecked.
Inspection by NESL team & the Solution Offered
Upon immediate intimation, NESL’s Online Leak Sealing Response Team reached the site within hours and conducted an on-site inspection.
Leak Characteristics:
- Leak Location: NRV Bonnet Joint
- Line Size: 6 inches
- Medium: High-temperature steam
- Pressure: 8 bar
- Temperature: 180°C
- Leak Type: Continuous fissure around bonnet circumference
Proposed Solution:
NESL recommended an online sealing intervention using:
- Brass wire peening to close open paths
- Injection of high-temperature resistant sealing compound (NESL – ½ A) suitable for steam lines up to 200°C
This solution would ensure zero shutdown and minimum disturbance to plant operations.
4. Safety Mitigation Protocols
The job was executed in strict compliance with NESL’s Online Leak Sealing SOP and BIS IS 18159:2023 industrial safety norms:
- PPE compliance: All technicians were equipped with fire-retardant overalls, insulated gloves, face shields, and steam-resistant boots.
- Permit to Work (PTW) obtained from client maintenance.
- Area isolation with barricading and caution signage
- Standby safety observer to monitor team health and emergency response
- Continuous temperature and pressure monitoring
- Toolbox Talk (TBT) conducted before job initiation
5. Execution of the Job
The job was carried out under the supervision of a senior technician with support from two experienced team members. The leak area was first cleaned and checked for temperature to ensure proper bonding. Brass wire peening was then applied around the NRV bonnet to reduce the leak path and help retain the sealing compound. NESL- ½ A compound, suitable for high-temperature steam lines, was injected using a caulking gun in multiple passes to fully seal the area. The compound began curing within minutes, and the team monitored the zone for 30 minutes to ensure the seal held steady with no further leakage.
6. Re-check and Assurance
After full curing a joint inspection was carried out along with the client’s maintenance head.
- The sealed area was visually inspected.
- No vapor emission or temperature drop observed.
8. Client Appreciation
The client expressed satisfaction over:
- The timely response
- Professional execution without shutdown
- Cost savings by avoiding valve replacement and downtime
This case once again demonstrates NESL’s leadership inemergency online leak sealing services across Indian industries. By complying with BIS IS 18159:2023 standards, adopting zero-downtime repair techniques, and deploying field-proven sealing compounds, NESL helped the power plant avert serious operational and financial loss.
If you are facing a similar problem at your please feel free to reach out to us: https://www.niccoengineering.com/contact-us/
