On chemical tankers the entry of personnel into cargo tanks is a more common practice than on oil tankers as a result of the requirement for inspections between grades etc; despite this, it is essential that the necessary checks are conscientiously made and recorded prior to entry in order to ensure the safety of personnel, enclosed space rescue equipment must be made ready for immediate use, reports Chemical Tanker Solutions.
SCAFFTAG Enclosed Space Tag system
On Chemical Tankers, entry into enclosed spaces should be treated with the same extreme caution. Entry into Enclosed Spaces, must be adhered to. The SCAFFTAG Enclosed Space Tag system must be in place to indicate which cargo tanks are safe for entry; these should be placed at the tank accesses or hatches. In the absence of a suitable “Safe Condition” tag, entry is prohibited.
Tank fans
Tank fans are most commonly used for ventilating cargo tanks.They are normally supplied with flexible ducting that may be lowered or pushed into the tank. The further that the ducting can be placed into the tank ( without its operator entering into the tank ) , the more effective it is.
Each member of the team entering the enclosed space must utilise the “Man in Tank” tags by clipping them onto the Entry Tag.
Entry into non gas free space / contaminated cargo tanks is prohibited, unless a risk assessment has been carried out and approved by the management office responsible for the vessel.
If this is agreed to, then in such cases, spaces should only be entered by personnel wearing breathing apparatus and appropriate protection against exposure to flammable, toxic or corrosive cargo vapours and, if practicable, a lifeline. Prior to such entry, reference must be made to ISGOTT, Chapter 11, Section 11.4.4,, ICS Chemical Tanker Safety Guide, Chapter 3.5 and IBC code concerning entry with Breathing Apparatus.
Risk assessment conditions
The following minimum conditions must be met with respect to such entries and included in the risk assessment.
- A permit must be issued by the Master stating that there is no practicable alternative to the proposed method of entry.
- Ventilation is provided where possible, provided this does not create a flammable atmosphere,
- Personnel use PPE and positive pressure breathing apparatus and are connected, where practicable, to a lifeline
- Means of communication are provided and a system of signals is agreed and understood by the personnel involved.
- Spare sets of breathing apparatus, a resuscitator and rescue equipment are available outside the space and a standby party with breathing apparatus donned is in attendance in case of an emergency.
- Work carried out in such circumstances will be limited to absolutely essential maintenance and or inspection only.
It may be necessary, especially during the carriage of Vegetable Oils etc, for personnel (shipboard or shore contractors) to enter the cargo tanks to carry out “squeezing” operations in order to maximise the cargo outturn. It is essential on such occasions that all Enclosed Space Entry precautions and procedures are in place both prior to and during the entry operations. Familiarity with the practice should not obscure the potential dangers of cargo generated vapours or an oxygen deficient atmosphere.
Cargoes such as of Coconut Oil may give off dangerous concentrations of CO (Carbon Monoxide) and when entry into tanks is required for “squeezing,” readings for CO in ppm (in addition to LEL, 02, H2S) must be checked and monitored prior to and during entry of personnel. Tank must be gas free 0% LEL, less than TLV for CO, H2S etc and personal gas meters with alarms should be used by persons entering the space.
If personnel are required to enter cargo tanks for hand cleaning with all Enclosed Space Entry precautions and procedures must be observed prior to and during entry, in such cases, full protective clothing and self-contained breathing apparatus must be worn.
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Source: Chemical Tanker Solutions
