Keep a ship safe with sealings

Malcolm Latarche

Malcolm Latarche · 11 September 2017


Often makers of what might be considered as incidental products are quite happy to supply them safe in the knowledge that they have been approved and tested for their intended use. Beyond that they may consider everything is for the customer to worry about.

Swedish seal specialist, Roxtec, could quite easily have done just that but instead it has decided to expand beyond just manufacturing and supplying sealings. It has established a new division to offer some much-needed advice and assistance in the field where its products and those of other similar suppliers are used.

Taken at their most basic, ships and offshore structures are primarily a series of compartments separated by relatively thin steel partitions. But things are not that simple and the integrity of the whole requires that partitions may need to prevent the spread of fire, flooding or gases and should be able to withstand heat and pressure to a certain degree.

Depending upon their location this may vary from a few minutes to two hours or more. The particular requirements are laid down in the construction and fire protection sections of SOLAS for ships and supplemented by class society rules and in a variety of national, industry body and class society rules for offshore structures.

While the steel structures themselves may be able to meet the requirements, they have the potential to be weakened by necessary penetrations to allow cable, pipes and tubing to be routed through the structure. This is also recognised in the various rules and regulations and while they are not usually prescriptive as to how the integrity of the structure must be maintained they do require that it is. That is where the many different types and makes of sealing systems come in.

The market for supplying sealing products is quite wide, and the types of seals and technologies used is varied. Most marine specialists could name at least a dozen suppliers and there are more local organisations supplying the shipyards in China, Korea and Japan. What may be an appropriate choice in one situation may be completely inadequate in another.

In general, penetration sealing products are familiar to all in shipping and offshore and to other industries besides, but they frequently do not attract much attention as to appropriate choices or to proper installation. During construction of the ship, such matters are left to the shipbuilder, their sub-contractors and the supervising class surveyor. When modifications are made in service and involve installation by an equipment supplier or contractor what attention is paid to any bulkhead or deck penetrations will depend upon the vigilance and availability of the chief engineer.

Over time the number of penetrations and the type of sealing systems used as new penetrations are made mean damage can be done to earlier installations. Inspections may be conducted by those with little knowledge and often no training in how a penetration should be installed.

Major incidents involving transit failures include the near loss of the BP Thunderhorse platform in 2005 and the flooding of Emma Maersk’s engine room in 2013. The number of times that fires, floods and gas escapes have been reported in other cases is indicative of a situation that needs addressing. Recognising that was case, Roxtec took the initiative to establish Roxtec Services as a service company to raise the awareness of transits and what role they have for safety and protection of marine and offshore assets.

Fredrik Timonen, Managing Director of Roxtec Services AB, stresses that it is not only concerned with how Roxtec products are installed and maintained, because this is a general issue related to all different brands of MCT’s, multi-cable transits, and other types of sealing systems. As a leading global sealing expert within modular cable and pipe penetration seals Roxtec Services inspects most kinds of systems and brands.

Highlighting the extent of the problem, Timonen said, “We are sad to say that in some ships/rigs more than 50% of the transits inspected have not been correctly maintained and in line with the manufacturers’ installation guidelines and certificates”.

“There are several reasons why that is reality”, he added, “Maybe the initial installation when the shiprig was built was not done with trained personnel who know how to perform a correct installation; Maybe the yard has no understanding of how additional installation details like insulation should be carried out to achieve Passive Fire Protection (PFP) according to TAC”.

Timonen explained that in many types of marine vessels and offshore rigs a lot of new equipment and cables are added when the ship/rig moves into operations. The service personnel have to know why the seals are there, and how important it is to get them correctly closed after every new additional cable or pipe.

Unfortunately transits on board rigs are today classified under what’s called “performance standard”, and not “system standard”. This means there is a lower demand for having the transits identified/tagged, and they don’t get linked to other systems on board which have frequent demands for inspections and functional testing. Transits get a low priority, considered “just a part of the deck/bulkhead”, even though they are in many cases as important as a sprinkler system to protect life and assets from fire, water or gas leakage.

Roxtec has a close cooperation with all class societies since it started its modular-based seals business in 1990, mainly with their engineering departments responsible for verifying its product performance and issuing Type Approval Certificates (TAC).

According to Timonen, “There has also been a lot of correspondence with class surveyors, most often for specific ship or rig projects. If they find installations believed to deviate from our TAC, they ask for our opinion and expertise. These requests from the class surveyors are often driven by the owners’ technical site representatives, who monitor that “they get the quality they pay for” from the yards”.

“Roxtec tries to increase the awareness of the importance of transits with all owners, but to be honest it differs very much how willing they are to look into these details. Our aim is to shift the overall status, so transits are no longer treated as bulk material, but as a system with a dedicated verification and maintenance routine. This message is aimed at both owners and classification societies”, said Timonen.

Timonen recognises that inspectors and surveyors can be under intense pressure. “Sometimes errors are not easy to detect, and it’s not fair towards class surveyors to assume they can be the detailed expert in every seal system and have the time for an adequate inspection when covering their full scope of duties on a vessel”. Timonen said.

The first Roxtec Services operations are situated in Sweden and Houston, to cover Europe and the US market and a new facility in Brazil is under startup. For the rest of the world, the company can provide services in almost any country through Roxtec’s “first line support”, and its several hundred man organisation, (if not taken care of direct by RSAB personnel). With that said, it can handle emergency calls rapidly although prefers to work with some pre-planning and project organisation.

The Journal

Published every February the journal is now recognised as the highest quality publication that covers all aspects of maritime technology and regulation and a must read for the industry.

More Details