Mumbai
The 4-inch gas exhaust line operates in a demanding refinery environment, exposed to thermal expansion and continuous vibration. The line carries hazardous and toxic exhaust gases, including unburnt hydrocarbons and carbon monoxide, making even small leaks a serious safety concern.
Previous repairs using conventional welding had experienced recurring problems, including:
Heat-affected zones and repeated thermal loading contributed to cracking and micro-leakage around welded joints.
Continuous mechanical vibration from upstream equipment created additional fatigue stresses around the welded sections.
Repairing the line through conventional welding required extensive isolation, gas-freeing procedures and strict hot-work controls.
Limited working space around the pipe rack made it difficult to consistently achieve high-quality full-penetration welds.
The challenge was therefore not simply to replace a damaged pipe section, but to find a repair method that could provide a reliable, leak-free connection without introducing another welded joint.
The repair was carried out through a controlled four-phase installation process.
The damaged 4-inch welded section was identified and removed using cold-cutting pipe cutters. The pipe ends were then deburred and the external surfaces prepared for the sealing system.
Insertion-depth markings were applied to ensure that the Pyplok® fitting was correctly positioned over both pipe ends before compression.
The hydraulic swaging tool was positioned over the fitting and actuated to create the permanent mechanical connection. The swaging operation itself was completed in less than one minute.
A physical Go/No-Go ring gauge was passed over the completed fitting to verify the final swaged profile and confirm that the connection had been properly compressed.
The project demonstrated how non-welded mechanical joining technology can provide a practical alternative to conventional welding for critical refinery utility piping.
By replacing repeatedly failing welded connections with precision-engineered Pyplok® fittings, the repair addressed the immediate leakage problem while also reducing the safety and operational challenges associated with hot-work repairs.
The successful intervention improved joint reliability, workforce safety and equipment availability, providing HPCL with an alternative approach for future high-risk gas exhaust and vent-line modifications.
Critical gas service
4″ Schedule 40 carbon steel gas exhaust line
Non-welded repair
Pyplok® cold-swaging technology
Leak prevention
100% leak-free seal verified after installation
Faster execution
More than 65% reduction in the repair window
No hot work
Cold installation without welding, flames or sparks
Zero incidents
Completed without safety incidents
When conventional welding is restricted or repeatedly fails in critical piping applications, non-welded mechanical joining can provide a faster and safer route to restoration.
At HPCL Mahul, the application of Pyplok® cold-swaging technology transformed the repair approach—from repeatedly repairing a vulnerable welded joint to creating a permanent mechanical connection designed for the operating environment.
The result was a leak-free repair with reduced downtime and without the need for hot-work welding.
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