Live-Line Weld and Composite Reinforcement on Clarifier Tank

RAK addressed an active leak on a white liquor clarifier tank operating in a highly caustic, high-temperature environment by performing live-line welding to immediately stop critical leaks. The area was then reinforced with a multi-layer composite system and protective coating to restore structural integrity and prevent future cracking. The entire repair was completed in service, maintaining safe, uninterrupted operations.

The Problem

A white liquor clarifier tank developed an active leak at the carbon-steel manway weld joint while operating in service at 170 °F. Cracks behind the repad caused continuous seepage despite lowered tank pressure. The highly caustic environment (pH 12–14) posed safety risks and increased the chance of further cracking. With no shutdown option, live-line welding under pressure was required. The repair area, 10 feet above grade, needed scaffolding and strict hot-work permitting. Immediate leak mitigation and long-term reinforcement were critical to ensure structural integrity.

The Solution

The repair was completed in two phases to address immediate and long-term needs. The first phase focused on live-line leak mitigation, sealing critical cracks with controlled welding while the tank remained in service. Major leaks at the bottom and sides were stopped, with minor seepage above the operating level left per requirements. The second phase reinforced the area with a multi-layer composite system designed for caustic service and high temperatures. A protective topcoat was applied for added chemical and environmental resistance, restoring structural integrity and preventing future leaks—all without taking the tank offline.

Project Pictures

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