Page 313 - International safety guide for oil tankers and terminals

CARGO TRANSFER EQUIPMENT
---ใช้เพื่อการศึกษาเท่านั้น---
18.2.6.5
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
18.2.6.6
Electrically continuous hoses should not have a resistance higher
than 0.75 ohms/metre measured between nipples (end flange to
end flange).
Withdrawal from Service
In consultation with the hose manufacturer, retirement age should
be defined for each hose type to determine when it should be
removed from service, irrespective of meeting inspection and
testing criteria.
The temporary elongations at which smooth bore rubber hose
assemblies should be withdrawn from service will vary with the
type of hose assembly construction, such that either:
a) The temporary elongation, when measured as in Section
18.2.6.3 above, should not exceed 1.5 times the temporary
elongation when the hose assembly was new.
For example:
Temporary elongation of new hose assembly: 4%
Temporary elongation at test: 6% maximum
or
b) For hose assemblies where the temporary elongation of a
ึ
new assembly was 2.5% or less, the temporary elongation at
the test should not be more than 2% more than that of the
new hose assembly.
For example:
Temporary elongation of new hose assembly: 1%
Temporary elongation of old hose assembly: 3% maximum.
Explanation of Pressure Ratings for Hoses
Figure 18.1 provides an illustration of the relationship between
several definitions of pressure that are in common usage. The
individual terms are briefly described below:
Operating Pressure
This is a common expression to define the normal pressure that
would be experienced by the hose during cargo transfer. This
would generally reflect the cargo pump operating pressures or
hydrostatic pressure from a static system.
Working Pressure
This is generally considered to mean the same as ‘Operating
Pressure’.
Rated Working Pressure (RWP)
This is the common oil industry reference that defines the
maximum cargo system pressure capabilities. This pressure rating
is not expected to account for dynamic surge pressures but does
include nominal pressure variations as expected during cargo
transfer operations.
Maximum Working Pressure (MWP)
This is the same as Rated Working Pressure and is used by BS
and EN Standards for designing hoses to these standards.
© ICS/OCIMF/IAPH 2006 279