Hydrex Founder Speaks about Evolution of Stern Tube Seal Repairs

Hydrex Founder Speaks about Evolution of Stern Tube Seal Repairs

Hydrex was established in Antwerp in 1974 by Boud Van Rompay. Since then it has steadily grown into a company the shipping and offshore industry can depend upon whenever there are tough and difficult jobs to do as well as for regular, routine maintenance and repair tasks.

Hydrex has built a reputation as the leading underwater repair and replacement specialist in the world. Providing a service that is both versatile and effective, the company has gained a standing as the most innovative and reliable company of its kind. We had the opportunity to meet with Boud to talk about one of the many technological developments Hydrex has pioneered in the last 40 year: Underwater stern tube seal repairs.

Boud Van Rompay: In 1998 our divers completed a seal repair training course led by John Crane Marine, who also worked together with Hydrex in the testing of new developments. At the end of 1999 we successfully started working with face type seals in Havant, near Portsmouth in England on what we considered to be the last barrier in replacing stern tube seals. It was a new and novel approach that was based on the strength of the mobdock (short for mobile mini drydock) applications that we had developed in the 70s, 80s and 90s.

Hydrex: I assume this was only the beginning?

Boud: Those early repairs were carried out on face type seals, that do not necessarily need a dry chamber or a dry habitat to work in. Soon it became apparent that we needed to find a solution for the lip type seals. We took it up again when we discovered it could be done with an inflatable habitat. We designed and manufactured such a habitat in cooperation with a supplier with whom we had previously worked, during the development of our bow thruster equipment. This new flexible mobdock enabled us to do a stern tube seal replacement in the dry as soon as 2002. The first application for that particular type of operation was done on a cruise vessel at the end of 2005. We replaced a 632mm diameter seal. This first success was a real breakthrough. After that it quickly became obvious that we could replace all types of seals. We performed ten more seals in the first year, for various manufacturers. These jobs went well: on each occasion the execution was done within the time frame that we had estimated. This usually is about two days.

Hydrex: And since then you’ve never looked back?

Boud: Our experience has been that it is quite feasible and very safe to do. We have managed to do all these stern tube seal operations within the allotted time frames and with the normal warrantees on the quality of the work. It’s not always straightforward to replace seals, because there can be quite a bit of variation in the configurations of the stern tube itself. There can also be complications with the liners, which can be worn down and show ruts. All this is routinely handled by the teams on the jobs. We typically work with 6-man teams that are perfectly capable of doing the work within the normal two days. We usually supply the equipment and the owner is free to supply his own seals. We can handle all type of seals from all manufacturers.

Hydrex: This type of repair sounds very interesting for owners, because ships don’t have to go to drydock.

Boud: The big advantage of stern tube seal replacements is that we can perform them in-situ, which means there is no need to take the ship to drydock. This saves you sailing time to the dry-dock, actual time in dry-dock, tugboat costs, demobilization and, especially for container ships or ships with cargo, you do not have to discharge and load/reload the vessel and provide for cargo space on the shore. We can service both loaded or unloaded ships, as we also provide afloat repairs. Afloat or underwater, the jobs are carried out very fast. There’s no interruption of commercial operations. All problems that can occur with stern tube seals are solved on-site, whether it’s an oil leakage or a total breakage of the seals.

Stern tube seal problems are a pain to have; oil leakages can be a major hindrance and produce a potential or actual liability when for instance going to the United States or other sensitive areas. When they have a leaking stern tube, ships are often not allowed to enter ports, or they can receive very heavy fines. A good example of this is the operation we performed on a general cargo vessel in Mobile, Alabama. Because the U.S. Coast Guard has very strict policies concerning environmental risks, they would not allow the vessel to sail to a different location before the oil leak had been permanently fixed. We therefore mobilized a certified diver/technician team to the vessel’s location to perform emergency underwater stern tube seal repairs. In order to provide the customer with the fastest possible response, flexibility was essential throughout the entire operation. Hydrex was able to perform the repairs in a very tight time frame and made sure that the vessel could continue on its schedule free of oil leaks.

So for a minimal cost and without having to drydock the vessel we can replace the seals and the owner is not burdened with an impromptu drydocking and the consequential problems such as time loss, financial loss, reputation loss ….

Hydrex: It seems almost incredible that you can do this on a worldwide basis and so fast: what is the secret to that?

Boud: All equipment that we need for this type of operation is available in two locations: At the Antwerp headquarters and at the Tampa Office in Florida. A third set will be stationed in Singapore very shortly. We have packaged our equipment in such a way that it can be sent in lightweight, aluminum cargo boxes that can go on any airplane. At the same time our divers have worldwide visas for almost all countries. So we have easy access to all locations and can immediately mobilize multi-disciplinary underwater technician teams together with equipment.

Hydrex: Stern tube seal replacements are only a small part of the range of repairs Hydrex offers. Can you quickly touch upon some of the other main services?

Boud: We can do other seals too, like propeller seals, bow thruster seals or anything that needs to be done on the rudder bearings. In this respect, we have recently developed a new spectacular way of performing dry and permanent repair or maintenance work on a rudder, which is quite a breakthrough. The Hydrex R&D department has also developed a repair system that allows Hydrex to perform permanent underwater repairs to every type of propeller in dry conditions. All kinds of repair or maintenance work can be carried out to propellers, twin propellers, variable pitch propellers, azipod and swing-up thrusters. With the implementation of these techniques our diver/technicians can now perform permanent repairs to all parts of the underwater ship propulsion system in drydock-like conditions.

Hydrex: Thank you for the interview.


Press Release, November 18, 2013