FEATURE/PATENTS

12Sealing Technology October 2013

team put together that could go out to the ves-sel to perform the operation.

A technique commonly used by leading man-

dedicated to meeting the requirements of offshore operators through innovation, some manufacturers have been working to provide an enhanced technique. Investing significant time and resources, they have been able to develop a viable, fully tested portable system that is capa-ble of replacing seals in-situ by optimising the billets welding technique for a seal profile.

Step-changeThe latest in seal-welding technology has more than met the challenge and is set to revolu-tionise the FSPO platform market. An exam-ple of this technology has been developed by Trelleborg Sealing Solutions (Figure 1).

It has designed a new seal which, manufactured from its established seal material, can be welded on board the platform without the need to return

the vessel to shore. By using a well-established and proven material, as opposed to a modified sub-stance, the company has been able to avoid inte-grating something which has not been fully tested into the new system to ensure full compliancy and reliability for the offshore operator.

Weld-head enclosureIn a controlled manufacturing area Trelleborg starts the process by producing a seal that is cut in one place using a specially designed tool. The product is then packed so that it is well protected to avoid any damage during transit.

Offshore – on board the FPSO – the seal is unpacked and installed on the swivel by highly trained personnel from Trelleborg’s service team. The engineers install it in the weld-head enclosure (part of the welding machine) which, certified to ATEX zone 1, is then pressurised so that welding can take place. Fully enclosed, production on other swivel stacks can continue without risk.

A control cabinet, which is purged and is also certified to ATEX zone 1, ensures the smooth running of the process, and performs monitoring and data logging. After the process is finished, the seal is safely removed from the weld-head enclosure before being polished and checked. If the values from the recorded data are satisfactory, the seal will be released for installation.

ConclusionSafety on board FPSO platforms is of para-mount importance and in the harsh offshore oil and gas industry operators must take every precaution to minimise risk at every turn. But at the same time spiralling maintenance costs and project downtime has proven to be a real issue for the offshore sector.

Seal welding is required for the smooth run-ning of an FPSO platform’s swivel stack – a critical element of on-board operations. For many years there has been a need to create a safe and reliable way of carrying out such a process in-situ. After years of development, Trelleborg Sealing Solutions has created a fully tested, portable system that is not only set to make life for the offshore operator safer and easier, but also dramatically improve the bot-tom line for the oil company.

Contacts:

Henk-Willem Sanders, Trelleborg Sealing Solutions,

FPSO Focus Group, Zeemanstraat 33, 2991 XR

Barendrecht, The Netherlands. Tel: +31 10 2922145,

Email: henk-willem.sanders@trelleborg.com,

Web: www.tss.trelleborg.com

Trelleborg Sealing Solutions Germany GmbH,

Handwerkstrasse 5–7, DE-70565 Stuttgart,

Germany. Tel: +49 711 78640, Fax: +49 711 780 3171,

Web: www.tss.trelleborg.com

This article is based on a presentation given at Offshore Technology Conference 2013 (OTC 2013), which was held in Houston, Texas, USA, in May.

Figure 1. Trelleborg Sealing Solutions’ seal-welding technology enables seals used in swivel stacks on board FPSO platforms to be welded in-situ, eliminating the need for the vessels to disconnect and return to shore.

PATENTSIndustrial robot sealing system

Applicant: ABB Research Ltd, SwitzerlandThis invention relates to a sealing system for an industrial robot. It comprises a sealing surface on a rotary shaft and a lip seal. The robot has several axes of rotation and uses drive units for rotating various parts according to these axes. At least one drive unit has a rotary shaft provided with the

sealing system described. The objective is to pro-vide an improved sealing system for the shaft.Patent number: WO/2013/075739Inventors: S. Li, A. Broberg, E. Johansson and A. ÖbergPublication date: 30 May 2013

Drill-bit seal containing spheres for wear resistance

Applicant: Halliburton Energy Services Inc, USAThis disclosure relates generally to equipment used for operations performed in conjunction

with a subterranean well. One example provides details of a drill bit with a seal that contains spheres which are embedded in a matrix mate-rial. These spheres – hollow glass micro-spheres – enhance the wear resistance of the seal.Patent number: WO/2013/081606Inventors: D.P. Duckworth and P.C. SuiPublication date: 6 June 2013

Fuel-cell seal assembly

Applicant: UTC Power Corp, USAThe fuel-cell manifold seal assembly described

PATENTS

October 2013 Sealing Technology13

includes a bracket and a retainer. The bracket is mountable on the manifold of a fuel-cell stack. The retainer extends closer to the stack than the manifold when the retainer is mounted on the bracket, and when the bracket is mounted on the manifold. The retainer limits the movement of the seal away from an installed position.Patent number: WO/2013/081575Inventor: M.E. FortinPublication date: 6 June 2013

Isolation assembly for applications in the marine industryApplicants: Schlumberger Canada Ltd, Canada; Services Petroliers Schlumberger, France; Schlumberger Holdings Ltd, UK; Schlumberger Technology Bv, The Netherlands; Prad Research and Development Ltd, UK; and Schlumberger Technology Corp, USAThis patent describes an isolation assembly for marine applications. It employs a pack-off device in an annular space between a landing string and a riser. The assembly is configured to seal off an annular space below the pack-off device such that potentially hazardous well testing applications may safely proceed early on in completion operations. In advance of any significant rig-level pressure-control equip-ment hook-up, the pack-off device may seal off the annulus from any potential hydrocarbon leaks up the riser towards the rig. Furthermore, where such a seal holds back pressure exceeding a predetermined level, a burst element may be incorporated into the wall of the riser to allow for controlled venting.Patent number: WO/2013/081808Inventors: J.D. Scranton and R. SuffridgePublication date: 6 June 2013

Rolling bearing unit with combination seal ring

Applicant: NSK Ltd, JapanThis invention aims to create a structure that prevents the entry of foreign matter into the in-seal space (26a) between a slinger (16) and a seal ring (17a). This structure ensures the movement of a seal lip (22a) with respect to the seal ring. A labyrinth seal (27a) is provided between the outer peripheral edge of a rotation-side circular ring section (19), constituting the slinger (16), and the inner peripheral surface of the stationary-side cylindrical section (23) of a core, constituting the seal ring (17a). Also, a thick wall-section (29) is applied to part of an elastic material (21a) so as to extend along its entire periphery. This elastic material con-

stitutes the seal ring. An auxiliary seal lip (32), which has a lower rigidity than the seal lips (22a–22c), is applied to the thick wall-section so as to extend along its entire periphery. The auxiliary seal lip (32) prevents foreign mat-ter from adhering to the seal lip (22a) and obstructing its movement.Patent number: WO/2013/081075Inventors: A. Takayama, Y. Shiono, M. Watanabe, M. Tanahashi

Publication date: 6 June 2013

Piston–cylinder design

Applicant: Técnicas Aplicadas de Presión Sl, SpainA gas piston–cylinder device (10) is described that comprises a body structure (1) and a pis-ton rod (2) that moves inside it. The interior of the body is occupied by a compressible gas. The device includes a bushing (20) between the body and the piston rod. This bushing has a deformable zone (40) that, in turn, contains a joining O-ring (3) which, in a leak-tight man-ner, connects the bushing with the inner face of the body. The zone is designed in such a way that when deformed it causes the O-ring to cease to provide a leak-tight seal at the connec-tion between the bushing and the inner face of the body.Patent number: WO/2013/079758Inventors:Publication date: 6 June 2013

Labyrinth seal

Applicant: Aktiebolaget SKF, SwedenA labyrinth seal has been developed. It has a first labyrinth ring and a second labyrinth ring.

When the labyrinth seal is in a mounted state the first and second labyrinth rings at least partly intermesh in an overlapping manner and can rotate with respect to each other. In the mounted state the surfaces of the first and second labyrinth rings – which face each other – have different wear resistances.Patent number: WO/2013/079535Inventors: A. Kern-Trautmann and M.SeuberlingPublication date: 6 June 2013

Rotary wheel sealing system

Applicant: Venmar Ces Inc, CanadaEmbodiments of this patent relate generally to a system and method for sealing a rotary wheel used in heating, ventilation and air-condition-

self-adjusting sealing system. Certain embodi-ments provide a rotary wheel assembly config-ured for use with a system for conditioning air supplied to an enclosed structure. The rotary wheel is configured to be positioned within a supply air-stream and an exhaust air-stream. The assembly includes a cassette frame, a wheel secured within the cassette frame and a self-adjusting seal sub-assembly configured to main-tain sealing contact with respect to a surface of the wheel. The sub-assembly includes at least one seal member. In at least one embodiment the seal member may include a membrane configured to be inflated or filled with a fluid, and a wear strip secured to the membrane. The

This invention, described by patent WO/2013/081075, aims to create a structure that prevents the entry of foreign matter into the in-seal space (26a) between a slinger (16) and a seal ring (17a).

Patent WO/2013/079758 provides details of a sealing structure, which makes use of an O-ring, for a piston–cylinder device.