UWG Group deploys digital levelling gauge
Posted: 13 August 2003
The DLG measures pitch and roll using high precision inclinometers,
calculates resultant tilt and azimuth (relative to the principle
axis of the instrument) and then displays the findings on an easily
readable LED display. The instrument is housed in a suitable casing
for subsea deployment and is mounted on an adjustable table to facilitate
The unit is operated via a light sensitive switch, and after a
suitable period the display is terminated and the unit reverts to
sleep mode to conserve battery power and prolong its operational
In its standard form, the DLG can provide in excess of 2,000 sets
of readings and can remain in sleep mode for approximately three
years, making the design appropriate for both temporary and permanent
The DLG was incorporated into the installation program of the Nini
and Cecilie templates primarily for the economic advantages it offers
over other potential options.
The client wanted to monitor the pitch & roll of the templates
during and after the pile driving operations.
Traditionally, a ‘bulls eye’ instrument could have
been used for this application, however the accuracy of such an
instrument can be relatively poor and the readability is often subject
to interpretation when observed via an ROV.
The potential alternative of reinstalling a gyro during pile driving
breaks was deemed to be uneconomic due to the high cost of the instrument
and the specialist survey technician required. In addition, such
a route would have delayed the installation process considerably.
The compactness, acute accuracy, simplicity and re-usability of
the DLG design proved ideal for these template installations.
During the pre-mobilisation calibration, the DLG was calibrated
to the subsea gyro module. This allowed the client to obtain a calibrated
pitch and roll while allowing the gyroscope to be demobilised prior
to commencement of the pile driving operations.
The vibrations from the pile driving operations tested the DLG
to far beyond the operational limits of other electronic devices,
but the client was able to obtain the critical data necessary to
confirm successful conclusion to operations.
The ROV pilots noted that the visibility of the digital readout
was far superior to other devices and they were able to fire up
and read the DLG from a greater distance (3m approx.) than any other
devices with which they had previously worked. This capability permits
the DLG to be placed along the main axis of any subsea structure
without concerns regarding the ROV’s ability to activate and
read the gauge.
Gary Maddern, UWG’s Project Engineer and Template Installation
Supervisor says: “This project perfectly demonstrated how
UWG’s DLG has the flexibility and durability to be used on
most subsea installations. The accuracy is second to none and highly
visible display will ensure that we will be seeing more of the DLG
in the near future”.
UWG Group provides: Deep Water Riser Engineering - Equipment Sales
and Rental - Well Systems Engineering - Well Construction, Intervention
Proven innovators in many disciplines, UWG Group member companies
include UWG Ltd, Team Energy Resources Ltd, Claxton Engineering
Ltd, 2H Offshore and WellCut Inc.
The Group employs approximately 160 staff worldwide.
For more informationsee www.uwggroup.com.
Posted by Richard Price,
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