Page 139 - International safety guide for oil tankers and terminals

SHIPBOARD SYSTEMS

7.3.1 Operation Manual
่อการศึกษาเท่านั้น---
The ship’s crew should have access to up to date drawings and information on
the cargo and ballast systems, and be provided with an Operation Manual
describing how the systems should be operated.
The cargo and ballast systems are subjected to many conditions that mayย์นาวี
The cargo system is one of the prime locations where breaching of cargo
containment may occur and care should be taken not to over-pressurise
sections of the system or to subject it to shock loads.

Operation of the cargo and ballast systems should only be carried out by
personnel who are familiar with the correct operation of the pumps and
associated systems, as described in the Operation Manual.
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7.3.2 Cargo and Ballast System Integrity

ultimately lead to failure resulting in loss of containment. These include the
following:

Turbulence in the flow, caused by poor pipeline design or excessive flow
rates, and abrasion due to solid particulates in the cargo or ballast, can
result in local erosion and pitting in the pipelines.
The main fore and aft pipeline runs are usually located at the bottom of the
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tanks and on the main deck where the effects of hogging, sagging and the
cyclical motions of a ship in a seaway are most pronounced. These
movements may result in damage to pipeline connections and bulkhead
penetrations, and to local external damage at pipeline supports.
Handling cargoes for which the system has not been designed. Particular
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care should be taken to prevent damage to cargo valve seals and pump
seals that are not suited to aggressive cargoes such as spiked crude oils.

Corrosion due to oxidation (rusting) when pipe systems are used for both
water and oil service.

Preferential corrosion is found where internal coatings have failed and the
corrosion is concentrated at a small location. This localised corrosion may be
accelerated when water is allowed to lie in the bottom of pipelines, in
association with sulphurous products from cargo or inert gas, or if electrolytic
corrosion cells are set up when pipeline connections are not securely bonded.

The presence of any latent defect in the cargo system will usually reveal itself
when the system is pressurised during the discharge operation. It is good
practice to pressure test cargo lines on a periodic basis, depending on the
trade of the ship. Although these pressure tests may provide an indication of
the system’s condition at the time of the test, they should not be considered a
substitute for regular external inspection of the pipeline system and periodic
internal inspections, particularly at known failure points, such as pump
discharge bends and stub pipe connections.
The presence of any latent defect in the ballast system will usually reveal itself
when the system is being used during the deballasting operation. The inability
to fully discharge or drain ballast tanks may result in stability problems on
double bottom or double hull ships and, in some instances, could result in the
ship being in an overloaded condition.

© ICS/OCIMF/IAPH 2006 105