Recently, Fassmer Shipyard in Germany opted to make Roxtec pipe penetration seals their new standard, replacing lengthy and expensive welding operations as a matter of course, and improving fire safety in the process. The move was deemed to be highly beneficial. “During construction, we enter multiple pipes through the opening and then adapt the seal to the diameters,” said Alla Klatt, Senior 3D Coordinator at Fassmer Shipbuilding Division. “We can even add pipes later.”
Welding is a hugely costly and time-consuming process for shipyards, and introduces a plethora of factors. It requires significant technical expertise, as well as attendant fire and safety personnel, and third-party inspection after the fact.
Whilst welding will remain integral to shipbuilding, repair, maintenance and retrofit programmes, there is one area in particular where methods stand to improve. Up to this point, many pipe penetrations have been connected to a transition piece (bulkhead union) which is subsequently welded directly to both sides of the structure, hence doubling the installation work. The increased levels of exposure to ‘hot works’, particularly during repairs or retrofit projects, result in anything deemed remotely flammable having to be stripped away from the area of operation, and firefighting personnel and equipment having to be on-hand at all times in order to prevent disaster.
Cutting out the middleman
By setting Roxtec pipe seals as its new standard, Fassmer Shipyard has foregone this costly, time-consuming and risky process entirely; instead, straightforwardly drilling a hole in the bulkhead, Fassmer can route pipes through, and fill the gap with a Roxtec rubber seal.
“Welders are skilled tradesmen but despite this, it still takes a significant amount of time to correctly weld a pipe or transition piece directly to the ships structure – and the larger the pipe, the longer the welded seam, “ explains Will Hoffman, Roxtec Key Account Manager, Global Pipe Sealing Solutions, Marine & Offshore. “It’s not a job which can be finalised in one go, as cooling intervals are required to complete a large diameter weld. Even getting ‘hot work permits’ on repair or retrofit projects can amount to a matter of days.”
Furthermore, there are times during a newbuild project or drydock, when a last minute alteration or addition is required. “Although [pipe] installations are designed and pre-prepared in advance, there are often instances where the project is close to completion, and someone realises there has been a mistake,” Hoffman explains. “By this time, the bulkhead is likely primed and painted – now, they have to take away that paint, re-weld, then re-prime and re-paint that damaged area.”
Roxtec SPM pipe seals comprise of a circular rubber-based element which expands via compression bolts to create a tight seal between the outside of the pipe, and the inside of the structure opening. The tight seal provides certified protection against fire, gas and water pressure. Completed in moments, only one side of the bulkhead need be accessible to complete the work, ideal in retrofit settings with inaccessible or potentially fire-hazardous equipment spaces. “In a repair or retrofit scenario with everything already installed, access becomes very difficult,” Hoffman adds.
The risk from fires is of major concern to Roxtec, since all parts of a bulkhead including the pipe penetrations must be capable of containing a blaze. This is one of the most challenging aspects of testing which takes place at Roxtec’s headquarters in Sweden. The fire resistant performance of Roxtec’s Roxylon compound (a variant of EPDM rubber with additional fillers and fire retardants) is continuously tested to various levels of fire rating standards and is certified and approved by DNV GL and all other CLASS Societies around the world; but work continues to explore the upper limits of the base rubber compound’s capabilities.
“There are two parts of our lab,” Hoffman explains. “In the fire lab, Roxtec is burning rubber 3 or 4 days a week. We also perform extensive water, gas, stress and exposure testing here. A few years ago we invested very heavily to improve the facilities and capabilities at our rubber laboratory to make it a world class testing facility.”
When it comes to pipe penetrations, one eye should be kept on the future, Hoffman indicates – that is, longevity. A seal that is water and gas-tight today might not be tomorrow, unless the right solutions are used. “All pipes vibrate, and anywhere you have forces moving in two different directions – say, a pipe and the structure it is welded into that forms a potential stress point,” he explains.
“Even a tiny hairline crack in that weld that can trap moisture or condensation; that’s how rust starts to happen. But if the pipe is not in direct contact with the structure because of a rubber ring absorbing that impact the long-term benefits are less direct stress on those pipe penetrations, and less long-term risks of corrosion.
Many work-hours, resource and administrative-intensive, welding is a finite process which cannot be easily altered or adjusted. Despite this, welding will always need to be done and the profession is not going anywhere. However, switching out this process in one particular application – pipe penetrations – improves yard efficiency and safety, and maximises flexibility for ship operators, as well.