Deadlegs

Deadlegs, also known as stagnant water zones, are sections of pipework in a fluid system that are no longer in active use but remain connected to the main system. These sections can trap stagnant water or other fluids, creating an environment conducive to microbial growth, corrosion, and potential contamination of the active system.

The formation of deadlegs typically occurs during system modifications, expansions, or when equipment is decommissioned but not properly isolated or removed. Common examples include unused branch lines, short pipe stubs left after valve removal, or areas of piping that are bypassed.

The presence of deadlegs poses several risks. Stagnant water can become a breeding ground for bacteria, which can lead to biofilm formation. This biofilm can impede flow, cause corrosion under the deposit, and potentially release harmful microorganisms into the process fluid. In potable water systems, deadlegs are a primary concern for maintaining water quality and preventing the growth of pathogens. In industrial systems, deadlegs can contribute to equipment failure through internal corrosion and can be a source of product contamination.

Mitigating deadlegs involves proactive design practices and regular system maintenance. During design, it is advisable to minimize unnecessary connections and to ensure that all disused sections can be effectively drained or isolated. During maintenance, regular inspections and identification of deadlegs are crucial. When found, deadlegs should be either removed from the system or properly capped and isolated to prevent fluid stagnation. This can involve removing the pipework entirely or installing blinds or plugs to ensure complete disconnection.