Maintaining a High Quality & Qualification Standard for Submarine Cables

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Maintaining a High Quality & Qualification Standard for Submarine Cables Heiner Ottersberg, Bianca Schulte, Heiko Dirks, Dr. Clemens Unger (Norddeutsche Seekabelwerke GmbH, NSW) Email: < heiner.

9-11, 26954 Nordenham, Germany Abstract: The exceptional requirements on robustness and reliability in an inaccessible environment have forced the submarine cable industry to meet the highest demands

1 Maintaining a High Quality & Qualification Standard for Submarine Cables Heiner Ottersberg, Bianca Schulte, Heiko Dirks, Dr. Clemens Unger (Norddeutsche Seekabelwerke GmbH, NSW) < heiner.ottersberg@nsw.com > Norddeutsche Seekabelwerke GmbH, Kabelstr. 9-11, Nordenham, Germany Abstract: The exceptional requirements on robustness and reliability in an inaccessible environment have forced the submarine cable industry to meet the highest demands in regard to quality and qualification. Within just the last few years, it appears that the cables and their ancillary equipment have become a commodity in their own right alongside the complex transmission equipment, highly developed optical components and the expensive implementation technologies. But if you take a look behind the scenes, you can see that the development and qualification of submarine cables is a rule model of engineering art. 1. PRODUCT DESIGN AND PERFORMANCE 1.1. INTRODUCTION Since the beginning of submarine telecommunication cable manufacturing in Germany, Norddeutsche Seekabelwerke (NSW) was founded in 1899 intended by the German Emperor, particular attention has always been paid to the quality of the product. Rigorous material and product control procedures have been performed right from the outset of early cable production and are maintained and documented to this very day. Data from the beginning of the 20 th century of detailed reception controls on raw materials are available until today. For example Figure 1 shows an extract from the Guttapercha reception control documentation in Figure 1: Extract from the Guttapercha reception control documentation in 1904 Copyright 2010 SubOptic Page 1 of 5

2 conference & convention In 1965, when the Transatlantic Telephone Cable (TAT 4) was manufactured, the insulation layer was already checked for defects by x-ray measurements. After the TAT 4 project, NSW ceased production of submarine transoceanic cables as a result of developments in communication satellite technology, notably the Comsat Agreement. The resumption of production with tailor-made cable designs for repeaterless applications started in the late 1980s due to the development and the growing commercial use of optical fibre communications. Only a few years later it was decided to transfer the know-how and experience gained from repeaterless technology to repeatered applications, thereby enhancing the portfolio of the product line (refer Figure 2). Figure 2: Cable family An area of paramount importance to new cable designs is the extensive qualification and type testing of the product to ensure it satisfies today s industry standard guidelines and recommendations. Safeguarding the quality of the materials and manufacturing processes should also be key to maintaining a consistently highgrade product output with repeatable results. In order to assure this objective, a fully certified quality management system in accordance with ISO 9001 was introduced, which is regularly reviewed by external auditors. An important aspect of this system is the formulation and implementation of procedures for Copyright 2010 SubOptic performing receiving, in-process and final inspections at key production steps. Furthermore, detailed analyses and calculations to describe the product properties are performed such as extensive investigations on the drag behaviour of the submarine cable for laying and recovery operations. In the following, a repeatered submarine cable family has been chosen as an example to describe the various steps required from the design stages through to final product acceptance THE CABLE FAMILY The Light Weight (LW) design of the NSW MINISUB R cable family for application in repeatered submarine systems is the basic design of all cable types within this family and consists of a central copper tube which accommodates the fibres loosely with a defined excess length. The central tube is surrounded by a high tensile strength steel wire armouring to guarantee the mechanical performance of the cable structure during installation and recovery for deep water applications. An additional outer copper tube acts as the composite conductor for power feeding purposes and is insulated and protected by a three layer sheath consisting of a semi conductive layer, an insulation layer and a layer for mechanical protection. Copper Tube Steel Wires Copper Coductor 3-Layer Sheath Figure 3: Cross section of the LW MINISUB R design Page 2 of 5

Based on above design, further cable types have been developed for specific applications, comprising a Light Weight Protected (LWP) design, a Single Armour (SA) design as well as a Double Armour (DA)

ANCILLARY EQUIPMENT To integrate the Repeater and Branching Unit (BU), NSW has developed a multi adaptable coupling using ball joint technology which allows motions in all spatial directions,

This recommendation describes test methods to analyse transmission, mechanical, handling, reliability and operational performance of a submarine cable.

In order to ensure the most consistently high level standards of cable production, all recommended test set-ups have been carried out on the members of the NSW MINISUB R family.

3 Based on above design, further cable types have been developed for specific applications, comprising a Light Weight Protected (LWP) design, a Single Armour (SA) design as well as a Double Armour (DA) design ANCILLARY EQUIPMENT To integrate the Repeater and Branching Unit (BU), NSW has developed a multi adaptable coupling using ball joint technology which allows motions in all spatial directions, ensuring flexibility for lay and recovery purposes. 2. QUALIFICATION AND TYPE TESTING PROGRAM 2.1. CABLE QUALIFICATION As a rule, submarine cables are qualified in accordance with ITU-T G.976. This recommendation describes test methods to analyse transmission, mechanical, handling, reliability and operational performance of a submarine cable. Testing includes, for instance, mechanical fatigue, hydraulic pressure resistance and high voltage or operational investigations relevant to a cable ship operation such as sheave and stopper tests. In order to ensure the most consistently high level standards of cable production, all recommended test set-ups have been carried out on the members of the NSW MINISUB R family. Figure 4: Ball Joint The main part of the coupling consists of a conductor housing with optimized design in consideration of DC resistance and accommodates the splice cassette and the mechanical cable termination. The insulation of the housing is achieved by the use of highly reliable molding technology. For optimization of the moulding process, the flow characteristics of the polyethylene can be analyzed by the Finite Elements Method (FEM) QUALIFICATION OF COUPLINGS FOR REPEATER AND BRANCHING UNITS The qualification of the couplings in accordance with ITU-T G.976 includes mechanical and reliability inspections of the cable with respectively integrated repeater or branching unit. In addition to the ITU-T recommendation, NSW carries out further investigations on molding performance such as x-ray verification, examination of microtome slices and high voltage tests. The ball joints are mechanically tested by tensile and bending tests. Figure 5: FEM Image of Mold Cavity Flow Figure 6: Molding samples (left) and bending test of a ball joint (right) Copyright 2010 SubOptic Page 3 of 5

4 2.3. UNIVERSAL JOINT QUALIFICATION The submarine cable design should be compatible with existing cable networks. This is typically achieved utilizing the well-established Universal Joint (UJ) methodology. The UJ is a standardized joint using common construction equipment which is able to connect all types of submarine telecommunication cables. The relevant UJ qualification work on the cable can be carried out in conjunction with a member of the Universal Jointing Consortium (UJC). Testing is broadly based on ITU-T G.976 but under the authority of the UJC in general SEA TRIAL As part of the qualification procedure, NSW carried out a sea trial under realistic conditions to prove the capabilities of the repeatered cables in combination with other manufacturer s Repeaters and Branching Units, self-developed accessories and the Universal Joint Technology. a light weight cable repair carried out. During the deployment phase, laying angle measurements were taken in order to verify in-house theoretical assumptions on drag behaviour of the cable. During the BU trial, spurs were laid out and rigged with mushroom anchors prior to deployment of the BU. Upon touchdown, the BU was then recovered on the trunk cable to verify that the tensile strength of the cable would support a recovery operation over the sheaves. One particular aspect of the sea trial was also visual inspection of the cable as it was recovered to deck. Encouragingly, the cable coiled back neatly into the vessel tanks without excessive torque. Offshore operations were further supplemented by stopper and Linear Cable Engine (LCE) tests as well as water ingress testing. The results of the sea trial were highly successful and sealed the acceptance of this cable product in the industry. The program consisted of a shallow water trial, a deep water trial and a BU trial. The trials included rigorous testing of the cable during deployment, repair and recovery scenarios. The application of fiber loop end seals allowed not only regular Optical Time Domain Reflectometry (OTDR) but continuous attenuation checks by power meter throughout operation. This was supplemented by regular insulation resistance measurements. As part of the shallow water trial, an armored cable section was deployed and the ends rigged with mushroom anchors. The cable was then deliberately cut and a repair performed using the previously qualified Universal Joint technology. Similarly, during the deep water trial, a mini-block with integrated repeater was deployed and. Figure 7: Laying of the BU Copyright 2010 SubOptic Page 4 of 5

5 3. SUMMARY This paper examines the various activities involved in the qualification of a submarine cable product from the design phase all the way to testing at sea, using state of the art cable laying equipment. It shows that from a historical point of view strong emphasis has been placed on stringent quality assurance measures in the course of cable production and that this approach is maintained and enhanced to suit today s requirements for a highly reliable subsea product. Further, the need for ensuring compatibility with internationally accepted standards of jointing is highlighted. Reference is also made to additional testing of ancillary equipment over and above the standard guidelines and recommendations. The combination of all the quality-relevant measures mentioned above will ensure that the product range is acceptable in the market, serving the resilience of subsea networks and therefore the reliability of subsea telecommunications traffic for the end user. 4. REFERENCES [1] Jose Chesnoy Undersea Fiber Communication Systems, Academic Press, Elsevier Science, USA, 2002 [2] G. Mahlke, P. Gössing Fiber Optic Cables, Corning Cable Systems, Munich, Germany, 4th edition, 2001 [3] International Telecommunication Union ITU-T Recommendation G /2007 [4] Heiko Dirks Wet plant considerations for high capacity / long haul system applications with passive amplification methods, SubOptic 2007, Baltimore, Maryland, USA, 2007 [5] Winfried Rutzen Repeaterless fiber optic telecommunication solutions as a powerful tool to overcome the challenges in the offshore oil and gas business, SubOptic 2007, Baltimore, Maryland, USA, 2007 [6] Heiner Ottersberg Synergy Effects of Products and Implementation Solutions for Scientific Submarine Systems and Offshore Oil & Gas Applications, SSC 07, Tokyo, Japan, 2009 Copyright 2010 SubOptic Page 5 of 5

DESIGNING AND DEPLOYING SPECIAL MULTI FUNCTION FIBER OPTIC CABLES

DESIGNING AND DEPLOYING SPECIAL MULTI FUNCTION FIBER OPTIC CABLES Heiner Ottersberg 1 NSW The Company Over 100 Years Experience in Cable Technology 1899 NSW (Norddeutsche Seekabelwerke) is founded by the