Page 51 - International safety guide for oil tankers and terminals

HAZARDS OF PETROLEUM

Whenever very high concentrations of H 2 S are likely to be present,
Emergency Escape Breathing Devices (EEBD) should be made available
---ใช้เพื่อการศึกษาเท่านั้น---
to all personnel working in hazardous areas who should already have a
personal H 2 S gas monitoring/alarm instrument.

Removing blanks for connecting the cargo hose or loading arm orย์นาวี
Personnel should be instructed that, if their alarm activates, they should
don the EEBD and immediately leave the area to an upwind location.
They should advise the central control location of the presence of a high
gas concentration in order that appropriate procedures can be initiated.

When H 2 S is known to be present, self-contained breathing apparatus
should always be worn if it is considered necessary to breach the
integrity of the cargo system and a vapour free atmosphere cannot be
งานห้องสมุด ศูนย์ฝกพาณิช
guaranteed. This would include the following activities:
Open gauging and sampling.

disconnecting the hose and blanking after cargo handling.

Cleaning filters.
Draining lines to open containment.
Mopping up spills.

Procedures should allow only for the use of air supplied by self-contained
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breathing apparatus. They should not include the use of chemical
cartridge respirators for protection against H 2 S vapours as the vapour
concentrations in the atmosphere may exceed the operational capability
of the respirator being used.

2.3.6.6 Corrosion
H 2 S is very corrosive and enhanced inspection and maintenance regimes
should be put in place if H 2 S is likely to be present in high concentrations.

Pressure/vacuum valve seats made of brass are more likely to fail than
stainless steel seats.

Mechanical tank gauges are more likely to fail since H 2 S has a damaging
effect on stainless steel tension springs and metals such as brass and
bronze. An increase in the spare parts inventory may be necessary.

Computer and instrument components made of silver and gold are highly
affected by even low H 2 S concentrations.

2.3.6.7 General Nuisances

In addition to being a health hazard, the H 2 S odour is also considered a
public nuisance. Most local environmental regulations limit or ban the
release of H 2 S concentrations to the atmosphere and this is, in any case,
good practice. It is therefore necessary to maintain cargo tank pressures
within acceptably low limits.

The tank vapour pressure will rapidly increase if the vapour space is
exposed to heat or the product is agitated.

Crude oil washing may rapidly increase the vapour pressure and should
begin at a relatively low pressure, preferably while maintaining a relatively
high discharge rate.

© ICS/OCIMF/IAPH 2006 17