MARINE INDUSTRY FOCUS


Cutting out the welding


Welding is an integral yet time-consuming and expensive process for


shipyards. However, Fassmer Shipyard has eliminated the process in one particular application – pipe


penetrations – by making Roxtec pipe fittings its new standard…


F


or shipyards, welding is a costly and time-consuming process, requiring significant


technical expertise, as well as attendant fire and safety personnel, and third-party inspection. An integral part of shipbuilding, repair, maintenance and retrofit programmes, there is one area in particular where methods stand to improve. Many pipe penetrations are 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 need to be on-hand at all times. Recently, however, Fassmer Shipyard in


Germany opted to make Roxtec pipe penetration seals its new standard, replacing lengthy and expensive welding operations as a matter of course, and improving fire safety in the process. Foregoing the risky process entirely, by 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 new build


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. For Fassmer, 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.”


PIPE PENETRATIONS 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 three or four 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 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,” Hoffman adds. Welding is a finite process which requires many


work-hours, is resource and administrative- intensive, and it 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, while maximising flexibility for ship operators.


Roxtec / DESIGNSOLUTIONS www.roxtec.com/uk DESIGN SOLUTIONS | MAY 2021 35


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