The industry is moving away from sealing plugs to other systems to protect pipes when passing through fire rated or watertight divisions. Here is why.
1. Long and heavy sleeves
Sealing plugs require a sleeve, and often a two-sided installation if there are fire rating, gas-tight and watertight requirements. The length of the sleeve typically depends on the diameter of the pipe and the material needed for the fire rating required. Therefore, most sealing plug solutions require sleeve lengths of between 100 and 250mm.
Long sleeves reduce the ability to add a joint or coupling to a pipe passing through the penetration close to the structure, or when trying to route the pipe system in a different direction. The shorter the penetration sleeve, the more flexibility exists when routing a pipe system within a confined space.
Longer steel sleeves also add weight. When extrapolating over multiple penetrations, the potential savings with lighter solutions becomes significant. Weight savings are important to support greater speeds, improved fuel efficiencies and a reduction in the environmental footprint.
2. Limited installation flexibility and large stock levels
Sealing plugs have limited tolerance levels, so specific sizing is vital. Attention to details such as the ID of the sleeve and the OD of the pipe are key to determining which plug is required. Two inflexible measurements without much tolerance require specific plug sizes to be on hand.
Due to numerous variances of the ID of the sleeves and numerous pipe OD options, a large selection of possible article codes exist from the sealing plug manufacturers. This can be very confusing and can quite often, result in incorrect selections.
If installers are not aware of the exact dimensions, the risk of the wrong size of sealing plug is very high because the tolerance levels of the plugs are limited. The result of an ill-fitting sealing plug could be catastrophic. Due to these reasons, most users of sealing plugs require a large stock or inventory carrying multiple article codes.
3. Extensive installation time
Most sealing plug solutions require welding of the sleeve on both sides of the deck or bulkhead, and welding is both time-consuming and costly. They require access to both sides of the structure, which can be hard during repair projects on a vessel or platform in service.
The air gap between the two sealing plugs often inhibits a smooth installation process. Much time is wasted in trying to manoeuver the sealing plug into position. As a result, many installations are left incomplete which has a significant impact on their overall performance.
These difficulties can be overcome if all installers follow the long list of installation steps, but most shipyards do not have the resources to follow every step, such as grinding out the inner edge of the sleeves or releasing the air pressure build up between the two sets of plugs. More time is wasted by trying to use brute force to finalize an ill-fitting sealing plug, or leaving a semi-installed sealing plug, which will require further work at a later stage.