Page 200 - International safety guide for oil tankers and terminals

INTERNATIONAL SAFETY GUIDE FOR OIL TANKERS AND TERMINALS

11.1.7.2 Controlling Electrostatic Generation
---ใช้เพื่อการศึกษาเท่านั้น---
Electrostatic discharge has long been known as a hazard
associated with the handling of petroleum products.
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
FAILURE TO FOLLOW THE GUIDANCE GIVEN IN THIS
SECTION WILL LEAD TO THE HAZARDOUS CONDITIONS
REQUIRED FOR ELECTROSTATIC IGNITION ACCIDENTS
TO OCCUR.

When a tank is known to be in an inert condition, no
antistatic precautions are necessary.

If a flammable atmosphere is possible within the tank, then
specific precautions will be required with regard to
maximum flow rates and safe ullaging, sampling and
gauging procedures when handling static accumulator
products.

Mixtures of oil and water constitute a potent source of
static electricity. Extra care should therefore be taken to
prevent excess water and unnecessary mixing.

ึ
11.1.7.3 During Initial Filling of a Tank

The generally accepted method for controlling electrostatic
generation in the initial stages of loading is to restrict the velocity
of oil entering the tank to 1 metre/second until the tank inlet is
well covered and all splashing and surface turbulence in the tank
has ceased.

The 1 metre/second limit applies in the branch line to each
individual cargo tank and should be determined at the smallest
cross-sectional area including valves or other piping restrictions in
the last section before the tank’s loading inlet.

Minimum Diameter of Piping* Approx. Flow Rate
3
(mm) (m /hour)
80 17
100 29
150 67
200 116
250 183
305 262
360 320
410 424
460 542
510 676
610 987
710 1,354
810 1,782

Table 11.1 – Rates corresponding to 1 metre/second

* Note that the diameters given are nominal diameters, which are not necessarily
the same as the actual internal diameters.

166 © ICS/OCIMF/IAPH 2006