Case Study Hydraulic hose bursting

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Introduction

On 10 May 1997, the
“JEANNIE,” on a voyage from Boulogne, France, was bound for Montreal,
Quebec. The vessel, under the conduct of a pilot, was abeam of Lotbinière,
Quebec, when the bridge watch realized that the rudder angle indicator was hard-a-port.
They tried in vain to bring the vessel back on course by changing the steering
gear mode from the steering position on the bridge. At approximately 2255, the
“JEANNIE” grounded on the south edge of the channel in the approaches
to buoy Q83, before the anchor could be let go or the main engine put astern.[3]
After the grounding, the tanks were sounded
and it was found that only the forepeak was holed. The vessel’s pumps were
unable to reduce the level of water in the tank below the waterline forward.
On May 11, at approximately 0700, two tugs
departed the Port of Québec to assist the bulk carrier. At approximately 1010,
as the tugs arrived on the scene, the vessel refloated herself on the rising
tide. At 1043, the vessel advised the Quebec Marine Communications and Traffic
Services that she had refloated and was anchored on the north side of the
channel.
The steering gear of the
“JEANNIE”, manufactured by Donkin & Co. Ltd., is of the
articulated-cylinder type. The gear consists of two units, each including two
double-action cylinders. Each unit is fitted with a constant-speed pump. These
pumps are mounted on a single hydraulic fluid reservoir. A multiple-valve
collector isolates either of the units for maintenance or emergency manual
operation.

Accident Analysis

Breaking of a Hydraulic Hose
Visual inspection of the hydraulic hose
showed that it was hardened and cracked and that it had separated from the
coupling. The deterioration of the hose is attributable to the surrounding
sources of heat and wear. When a break occurs on a hydraulic component, the
single reservoir quickly empties its contents because of the constant-speed
pumps.
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Alarms

When the amount of hydraulic fluid in the
reservoir drops to a predetermined level, an alarm sounds in the engine control
room. A crew member has to go into the steering gear compartment, identify the
problem, shut off four valves using a special wrench, and then open two other
valves to isolate the unit in trouble and thereby restore steering capability
to the vessel. When the first person arrived in the steering gear compartment,
the hydraulic fluid reservoir was already empty; thus, nothing could be done to
counter the failure.
The low-level alarm apparently sounded in
the engine control room. On the bridge, it was noticed that something was wrong
when the rudder-angle indicator read hard-a-port and the helmsman could not
return the helm amidships despite his efforts. The alarm was apparently not
heard by the personnel on the bridge.
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Reservoirs

In spite of the direct access to the
steering gear compartment from the engine-room, the system was designed in such
a way that it would have drained completely even with the intervention of an
engineer. The two units are supplied by a single reservoir and there is no
storage tank permanently connected to the hydraulic system. Had each of the
units been fitted with an independent reservoir, the steering gear would have
remained in operation without intervention by the personnel. On some of the
more-recently built vessels, the steering gear remains in operation even when
one of the units fails.
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Regulations

Canadian regulations require that in the
event of a failure, steering capability be maintained or speedily
restored. The requirements are more stringent, however, for tankers and
chemical tankers of over 10,000 gross tons. Such vessels have to be able to
restore steering capability less than 45 seconds after failure of a power
transmission system. In confined waters, all vessels should be able to regain
steering capability in the event of failure regardless of their size or type.
Several domestic and foreign tankers and chemical tankers of less than 10,000
gross tons that transit the St. Lawrence River and other confined waters
in Canada are not subject to these requirements.
The loss of hydraulic fluid from one of the
systems must be able to be detected and isolated automatically so that another
system or systems can remain operational.
The International Convention for Safety
of Life at Sea (SOLAS), Ch. II-1,
Part C,
contains regulations for steering gear that are adopted by some classification
societies and are also found in the Canada Shipping Act. These
regulations apply to all convention vessels. Some of them read as follows:
Regulation 29, Art. 1:

. . . [t]he main steering gear and the auxiliary steering gear shall be so
arranged that the failure of one of them will not render the other one
inoperative.

Regulation 29, Art. 6.1.3:

. . . the main steering gear is so arranged that after a single failure in its
piping system or in one of the power units the defect can be isolated so that
steering capability can be maintained or speedily regained.

Regulation 29, Art. 12.2:

. . . a low-level alarm for each hydraulic fluid reservoir to give the earliest
practicable indication of hydraulic fluid leakage. Audible and visual alarms
shall be given on the navigating bridge and in the machinery space where they
can be readily observed; and

Regulation 29, Art. 12.3:

. . . a fixed storage tank having sufficient capacity to recharge at least one
power actuating system including the reservoir, where the main steering gear is
required to be power-operated. The storage tank shall be permanently connected
by piping in such a manner that the hydraulic systems can be readily recharged
from a position within the steering gear compartment and shall be provided with
a contents gauge.


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2.5 Compatibility with International
Requirements
Where the main steering gear comprises two
identical power units, it should have the same capability and reliability as a
main power unit fitted with an auxiliary steering gear, and be capable of being
brought into operation from a position on the navigation bridge. In the event
of a power failure to either of the steering gear power units, an audible and
visual alarm must be given on the navigation bridge.
The steering gear of the
“JEANNIE” met regulatory requirements at the time of its
construction. This type of steering gear, in use on both foreign and Canadian
vessels, can be modified to prevent such a failure.
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Conclusions
Findings
A steering gear hydraulic system hose
separated from its coupling, causing the hydraulic fluid reservoir to empty.
The crew could not intervene in time to
isolate the defective power unit.
A single reservoir supplied both steering
gear units, and there was no storage tank permanently connected to the
hydraulic system in such a manner that the system could be speedily brought
back into operation.
No audible or visual alarm indicating the
problem was noticed by the crew on the bridge.
Following the failure of her steering gear,
the “JEANNIE” grounded, causing damage to her forepeak.
This type of steering gear is in use on
both foreign and Canadian vessels.

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Causes

The “JEANNIE” ran aground because
a steering gear hydraulic hose failed and the crew of the vessel could not
intervene and regain steering control before the two power units became
inoperative.

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