When a boiler feed pump trips, flow reverses within milliseconds. A slow-closing check valve lets the reverse column build velocity, then stops it violently — cracked discs, sheared hinge pins and a pressure spike travelling back into the feed line.

Two-shift operation and frequent starts cycle valve bodies through large temperature swings. Cracks initiate at section changes and body-to-bonnet corners long before the pressure rating is reached.

Wet steam and high-velocity condensate wire-draw seat faces in minutes when a valve is used to throttle. The valve then never seals again in the closed position.

Feedwater close to saturation flashes across the throttling point. Collapsing vapour bubbles pit the trim and can destroy the downstream body bore.

A leaking stem on any sub-atmospheric line pulls air into the condenser. Back pressure rises, heat rate worsens, and the whole unit loses output for a fault worth a few thousand rupees.

Large-bore CW lines carry enormous momentum. A fast-closing valve or a pump trip without controlled closure creates a surge that can move pipe supports and split joints.

Bottom-ash and fly-ash slurry is aggressively abrasive. Standard seats and body bores are cut away in a single season on high-flow lines.

Coastal stations on sea or brackish water and inland stations on silt-laden canal water both attack standard cast-iron and carbon-steel wetted parts.

Packing consolidates and relaxes after each thermal cycle, and a steam leak on a hot line is a safety issue before it is a loss issue.

A 1970s or 1980s station often runs equipment whose original manufacturer no longer supports it. Lead times of six months against a unit sitting idle are not acceptable.