Page 46 - CHIRP annual digest 2016.pdf

CHIRP Maritime

5. Machinery and Design Issues

Article. 34 Immediately after the isolating ball valves, we will fit stub
Exhaust Gas Heater Fire Suppression pipes with a further ball valve fitted on each line. This valve
System- Large Ferry will serve two purposes:
1) to check for any water leaking past the isolating valves
In the course of work to fit exhaust gas scrubbers in a large and
ferry, pipes serving the exhaust gas heater fire suppressant
2) to connect an air hose and blow air up through the
system had to be cut; pipes/nozzles were found to be nearly supply lines and nozzles to prove clear. This will be put
blocked and thinned. This would have prevented the system
into the Planned Maintenance System as a routine
from working as designed in event of fire. The cause was (probably monthly) job. These ball valves will have
probably leakage past isolation valves allowing seawater to
plugs fitted in the outlets at all times when not in use.
enter the ‘supply lines’. Salt then crystallized in the heat. The valves will be fitted with clear signage as to their
The comprehensive report outlines remedial action.
purpose’.
Extracts from the information passed to CHIRP. ‘Given the
condition of the pipes and nozzles – had we had a fire in Lessons to be learnt
the exhaust gas heaters, it would have been very unlikely This comprehensive report detailed how a fault, which
that the fire suppression system would have had any could have had serious consequences, was discovered
effect. The reason for the blocking of the nozzles is that it in the course of routine work. It then laid out the
is suspected that the isolating valves on the fire main have actions that were taken to rectify the fault (by the
been leaking past, allowing sea water to fill the supply lines replacement of piping), and the measures instituted to
and when reaching the hot environs of the exhaust gas ensure regular testing in both company ships fitted
heaters, the water has rapidly evaporated, leaving a build with the system.
up of hard salts in the nozzles.
A natural question surrounds the symptoms that might
indicate such a problem in the making. For an emer -
gency system, this may well be difficult. However it is
crucial that all emergency systems have stringent
inspection/test regimes, preferably controlled within
the ships Planned Maintenance System, to ensure
successful operation if required. The inspection/test
regime may identify design shortfalls, as experienced in
the report, which will initiate corrective action involving
redesign, material selection, avoidance of water traps
(u-bends) and improved testing techniques.

CHIRP Suggests
Take note of this case. Check similar installations in other
Heavily obstructed pipes – Ferry Fire Suppression System ships, and ensure that regular and reliable inspections are

We are proposing some modifications to the fire suppression followed. Watch for ‘out of sight, out of mind’. Emergency
system: The nozzles and pipe-work will be like for like, but gear of all kinds, including fire fighting gear, is not in
with a different routing to allow easier access for inspection regular use; defects may therefore go unnoticed. And yet
in the future. Pipes and nozzles will be galvanised. New – when these equipment are needed – they are needed
valves will be fitted to the fire main at the branch off of the immediately and in full working order to save life. Invest
supply lines. The original valves are ‘globe’ valves, we intend in their maintenance.
to change these for stainless steel ball valves. The above article was published in MFB42

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