02/23/2024
Underwater Construction Plugs and Sealing Bulkheads: Temporary to Permanent Tunnel Water Stop and Pressure Barrier Products
Deployable pressure sealing bulkheads are used as temporary to permanent pressure-containing barriers in tunnel, drift, pipeline, and shaft systems, allowing short and long term construction rehabilitation projects as well as new construction to safely commence. Underwater construction barrier products are typically installed using underwater technicians, divers, and rov’s to install the barrier product into the intended location. These products typically work with existing infrastructure to provide leak-proof seals and handle pressure restraint locally. The greatest benefit of these products is, as their name would imply, that they are portable – able to be safely installed, moved, or removed quickly, and in some cases, even in the presence of flowing water.
These products are typically composed of a pressure barrier structure, a mechanical restraint (or hold-in place device), and a sealing system. Restraint structures are either lock in place dogs & grippers, anchoring systems, strong backs, and other, typically cleaver bearing or tension devices. Sealing systems typically employ gaskets or usually, when maximum sealability is required, an active mechanical or inflatable seal. It should be noted that in the case of a critical isolation activity (single barrier isolation, workers working directly in the path behind the tool, v***r isolation in the presence of welding or hot work, or when critical infrastructure could be exposed to failure) an active mechanical seal or redundant inflatable seal set or even an inflatable/mechanical duel system is preferred, or required in some locations.
Similar to portable piping isolation tools, there are many similar products for round, rectangular, and irregularly shaped tunnels, drifts, and bores. Many of these products can function as a seal and restrain on the inlet (via strong backs) or restrain in place in the tunnel using anchors, restraining dogs, or other friction or bearing/tension systems. Active sealing systems are typically required in irregularly shaped tunnel networks to ensure sealing in sharp corners, on defective surfaces, and ever-changing gap spaces around fixed structures. Many of these designs can also be configured for diver or even ROV installation in submerged tunnels, intakes, penstocks, and more!
There are many types of portable pressure isolation barriers used to block the flow of open channel flows, as an alternative to gates and stop log systems. Some of these include top anchor systems that do not require technicians to enter the water to activate seals or install anchors below the waterline. Others take advantage of existing stoplog channels or employ friction based systems to lock directly in place against the walls once lowered into position.
The attached product example illustrates an anchor in place bulkhead product that was successfully installed using divers in 2024. This system employed a SEALFAST® Inflatable and Active Mechanical Seal to provide optimal sealing performance in unknown surface conditions due to the remoteness and age of the installation site. An elastomeric filler band was used to allow installation of the bulkhead into multiple side tunnel cross sections for safety and design flexibility.
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