Archived News 2000-1998
Fibre Optics Refocussed
The broad band capabilities of fibre
optics are drawing many more designers to this technology. Market research
has identified that there is a growing requirement for custom underwater
fibre optic penetrators and connectors. These may be optical only or of hybrid
construction. In response PDM Neptec are refocussing their fibre optic activities
to specifically support the specialist market.
Having established the underlying techniques for handling, preparing and
processing fibre optic cables, PDM are looking to develop the custom market,
drawing on their extensive experience with electrical underwater connectors.
The company has over 15 years experience in connectors, harness assemblies,
elastomers and material bonding & processing techniques. PDM will develop
monomode and multimode products for commercial and military projects. From
the client's point of view, they can obtain all their harness requirements
from one source.
PDM Neptec have just completed two new custom underwater fibre optic projects
- penetrator assemblies for Smart Fibres and connector assemblies for Thomson
Marconi Sonar. A photograph of the Smart Fibre assembly is shown above.
If you wish to discuss a specific project or would like some more background
information, please contact Ian Doble at PDM.
Submarine cable protection
PDM manufactures an extensive range
of bend restrictors for the submarine cable industry. A typical Alcatel cable
laying operation with an ROV is shown in the picture above. Devices can be
produced for large and small applications with dynamic or static loading.
The products are manufactured from polyurethane elastomers specially selected
for their mechanical properties.
New buffer design for Global Marine Systems
Introduction
PDM's involvement in bend control products goes back over ten years. During that time it has produced products for all the major contractors.Bend limiters (or "buffers") are widely used on cable assemblies where the cable moves in service. They restrict localised bending, particularly at an attachment point. They are designed so that, for a given load-angle combination, the cable is not bent beyond its recommended minimum bend radius (MBR) over length of the buffer. The cable MBR will be greater for dynamic as opposed to static in-service conditions.
The Global Marine Systems Project
PDM was commissioned by Global Marine Systems to design, develop and manufacture a completely new version of the UJ Unarmoured Protection Kit (Kit 10011). The design required a double ended buffer configuration, protecting an in-line cable joint.The specific challenge of this contract was to design the product without the use of metal components. The product must also survive the harsh subsea operating environment and in-service loading. The requirements were met using specially selected polyurethane elastomers and a novel design. The two moulded buffers were held together by a reinforced interlock system.
Following the development programme the performance of a pre-production protection kit was successfully validated against a series of qualification and characterisation tests approved by the client (see picture).
The above project is an example of a typical comprehensive design, development and manufacturing programme carried out by PDM. Whether you require simple or complex moulded components, please contact PDM, who will be pleased to discuss your requirement.
Comprehensive Engineering Solutions
Drawing on its diversity of experience
in the areas of connectors, harness design, cable termination & moulding,
bend control, encapsulation, elastomers and engineering materials, PDM is
able to offer comprehensive solutions to underwater projects.
In many cases the experience held by an organisation, for say transducer
design, is not necessarily synonymous with a knowledge of the engineering
and materials skills described above. Today it is logical to consider having
these tasks performed by an organisation specialising in these areas as opposed
to keeping an in-house team capable of the work. This approach makes good
economic as well as technical sense. In a typical project of this type PDM
could: provide or custom design connectors or penetrators, design and manufacture
the harness assembly and encapsulate the transducer, all as an integrated
service to the client.
PDM has an increasing number of clients taking this approach and more details
have been published in the PDM Newsletters over the last year or so. This
quarterly publication has recently been directed to demonstrating the diversity
of projects where PDM provides the broad underwater engineering functions
described. If you do not already receive the Newsletter, and would like to
do so, then please call PDM and ask to be added to the circulation. You can
also request back issues which will give you a greater insight into PDM's
range of expertise.
Over the last couple of years PDM has made
significant contributions to the following major projects:
- The SOC Autosub autonomous underwater vehicle
- The SMD/TM Nereus cable maintenance ROV
- The Divex STEALTH (TM) diving equipment (image above)
- The Ultra/Sonavision Deepscan 120 bathymetric sidescan sonar (image above)
- The TSS 340 Series pipe & cable survey system
- The HEL seismic gun array
If you have an interest in any of the areas described, please contact PDM and one of our Application Engineers will be pleased to help you.
Electrical Cable Harness Production
As an introduction to one of the principal PDM product lines, this section will give an indication of two interesting and challenging harness systems PDM has produced.Where an application is situated in a static clean water environment the harness design has merely to concentrate on the internal construction of the product. Some requirements are, however, far from this simple model. To indicate the challenges presented by more complex systems two interesting projects are described below. All PDM Neptec production work is carried out under BS EN ISO 9001:2000.
SOC Autosub
This fascinating project concerns the
production of a totally autonomous underwater vehicle. The vehicle itself
comprises three main sections - the scientific payload, the power management
& buoyancy systems, and the propulsion unit & fin actuators. The
harness system developed by PDM was required to service all main functions
and was contained in the free flooded sections of the hull. The harness needed
to withstand the operational environment and was to be subjected to frequent
movement due to the water flow within the vehicle. In addition, due to the
autonomous nature of the vehicle, reliability of the complete harness system
was of paramount importance. The harness produced by PDM comprised high
performance metal shell connectors with rugged breakout mouldings. The Autosub
vehicle has now carried out in excess of 130 missions over a period of two
years, during which time the connector system has performed reliably.
SMD/TM Nereus
This type of cable maintenance ROV
needs a sophisticated array of functions. Nereus can operate at depths up
to 2000m. The ROV can operate at up to 3 knots in free swimming mode, and
in tracked mode can move over the sea bed at speeds up to 3000m/h. In addition
to a comprehensive selection of cameras, Nereus is able to bury cable up
to 1m deep in the sea bed using its dual pressure jet tool. This tool throws
up sediment into the water column subjecting the harness assemblies to continuous
abrasion. The new Titan metal shell connectors are ideally suited to this
type of demanding application. The Nereus termination mouldings are backpotted
for maximum reliability and the substantial multiway mouldings are fully
waterblocked. PDM has extensive experience in producing harness systems for
this type of demanding application particularly for ROV and seismic systems.