Geo Therm Ltd safety case study about installing IR windows into a offshore drilling rig electrical systems to support PM inspections into MV/HV critical equipment

1. June
2020
Issue
92
The Magazine of the International Institute of Marine Surveying
THEREPORT
Airborne & Structure
Borne Ultrasound
Salvors save 2.3 million
tonnes of pollution
Fastenings: what a surveyor
ought to know
Construction
requirements for
an innovative
new build
How to survey a mast,
its rigging and sails

2. 74 | The Report • June 2020 • Issue 92
SAFETY
CASE
STUDY
OFFSHORE JACK-UP
RIG INFRARED
WINDOW RETRO-FIT
Performing electrical thermographic
(IR) surveys can often be fraught
with danger from electrocution and
arc-flash being the most threatening
hazards to life and equipment.
Critical equipment can often be
missed during IR surveys due to their
operational or interlocked state.
Preventing identification of loose,
high-resistance, high temperature
terminations likely to fail...
74 | The Report • June 2020 • Issue 92

3. The Report • June 2020 • Issue 92 | 75
In November 2019 Geo Therm
Ltd were tasked with performing
the first electrical thermographic
survey on the Valaris Plc
premium Jack-up the JU-123.
And requested to assess the
number of infrared windows to
facilitate the inspection of critical
electrical equipment. The asset
equipment identified included
seven CAT generators (including
the emergency generator)
and ten plant transformers
necessitating a total of #93
infrared windows for installation.
In Dec 2020 Rig management
authorised our world class
services to procure and install the
#93 IR windows whilst the asset
remained berthed in Dundee
Scotland. As the owners deemed
the installation would be more
effective when under shore power
rather than in an operational
state. The CorDEX Type IW3000
Infrared windows with a 75mm or
3” diameter crystal window were
chosen. Benefiting from being
ABS type approved and arc-flash
resistance test rated to 11KVA.
Three IR windows were retrofitted
into each of the CAT 3516CHD
main engine generator terminal
boxes and E-Gen terminal box
covers. And twelve into the
two main drilling transformers
and a range of one to six IR
windows were also retrofitted
into various rig-wide distribution
transformers. The retrofit took
the Geo Therm Ltd technician six
days to complete, aided by the
on-board rig electrician.
The benefits of this installation of the infrared windows were:
- Confirm if loose/high resistance hotspots exist in closed critical systems.
- Prevent electrical shock & triggering an arc-flash explosion when needing access
- Enable future thermographic, visual and spot-infrared PMR’s to be safely realised.
- Effective inspections, easier and faster future access without service interruption.
- Facilitate PM scheduling when a hot-spot is found, to prevent a breakdown or downtime.
The JU-123 (Jack up rig) is the
newest of the four Valaris Plc 120
series harsh environment Jack-
ups currently in operation in the
UKCS. And is one of 74 rigs in the
owner’s fleet, currently the world’s
largest offshore drilling company.
PHONE:
+44 (0)1502 723241
WEBSITE:
www.geothermltd.co.uk
EMAIL:
tonydale@geothermltd.co.uk