Survitec has welcomed industry initiatives to install Inert Gas (IG) systems to smaller oil and chemical tankers less than 8000dwt.
Acknowledging the positive impact of 2016 amendments to SOLAS, which mandated the fitting of an IG system to newbuild tankers of 8000dwt and above, Survitec says it has seen a number of IG installations to smaller vessels following recent industry calls for a revision of the rules to include all tanker sizes.
The amendments written into SOLAS II-2/4.5.5 and II-2/16.3.3 have gone a long way in preventing fatal explosions aboard larger oil and chemical carriers but we do recommend that operators of existing and smaller oil tankers not already covered by the SOLAS requirements should consider installing a system.
said Bernt Ohrn, Managing Director, Survitec’s Maritime Protection brand and continued saying that “If you are carrying a cargo with a flashpoint of 60°C or less, then you really should have an inert gas system onboard.”
Prior to 2016, only oil tankers of 20,000dwt were required to have an IG system installed, but the rules were revised after a spate of serious incidents, including 2004’s fatal explosion aboard the Bow Mariner.
A number of incidents involving vessels of smaller tonnage, however, led to calls for another revision to include all oil and chemical tankers, irrespective of size.
Ohrn while referring to an inter-industry working group study published in 2017, noted that the majority of reported incidents occurred during tank cleaning, venting or gas freeing. And in several cases, the tank atmosphere for non-inerted tanks had not been evaluated or was not being monitored.
These incidents are avoidable, as reports show. The installation of an inert gas system on tankers of all sizes that carry flammable cargoes is both technically and operationally feasible, yet only a small percentage of the global tanker fleet has installed technology designed to purge cargo spaces of hazardous vapour.
said Ohrn.
An IG system is used to remove oxygen in a space with hydrocarbon vapours in cargo tanks to less than 8% by volume. Where tankers are not fitted with the system, flammable vapour is vented until outlet concentrations are less than 30% of the lower flammable limit.
Ohrn also mentioned that given the mass and energy of an explosion at a shore-based terminal or port storage facility, a number of operators are making it compulsory for tankers to be inerted prior to entering the facility.
I think the transportation side of the industry can learn from the ports and storage terminal side. When it comes to safety there should be no debate, no discussion. Safety comes first.
he concluded.
Inert gas is an asphyxiant due to the low oxygen content and contains low oxygen levels for life support, CO2, CO, NOx, SOx and traces of other substances. In addition, some of its components (e.g. carbon monoxide, sulphur dioxide, etc.) are toxic. Thus, all personnel onboard need to be aware of potential hazards which may arise due to leakage of inert gas and take precautions.
Why inert gas is important onboard
An inert gas system is a crucial system for safety against explosion onboard. Namely, inert gas systems are essential on ships that frequently carry hazardous cargoes with some of the most dangerous being those that are explosive or flammable. This important integrated system can be through as a separate inert gas plant or flue gas produced by ship’s boiler. Use of inert gas systems in dry cargo vessels is voluntary but for oil and chemical tankers it is compulsory under SOLAS and more specifically chapter 15 of the Fire Safety Code.
Precautions
Entry into an inert space is normally not allowed. In the exceptional case, when entrance is absolutely necessary, do not enter the space without the aid of a Self-Contained Breathing Apparatus (SCBA) and special suit. If the skin or eyes come into contact with combustion deposits associated with inert gas, coveralls, chemical resistant gloves and goggles shall be worn. Do not eat, drink or smoke in areas where combustion deposits are present. Wash hands before eating, drinking or smoking. Wash contaminated clothing prior re-use.
Inert gas does not affect hydrocarbon or toxic gas levels in a tank atmosphere. Dilution of an inert atmosphere when vented may result in pockets of gas which are within the flammable range and which may be toxic. When gauging or sampling operations are taking place, personnel should avoid standing in the path of vented gas. Whenever a tank is kept inert at positive pressure, personnel should be alerted to the potential hazards of this pressure. Pressure should be reduced prior to opening tank lids, ullage ports, tank cleaning hatches, etc.
