Safe Handling of Tank Containers - ITCO

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ICHCA International Safety Panel Briefing Pamphlet No 30 purpose of cooling the pumps down and for diverting the liquefied gas flow through the pump itself. 5.6.5 Pressure Bleed Valves 5.6.5.1 Tank containers are built to a given pressure rating which is linked to its “holding time” (see Annex 1 Definitions). Although every precaution possible is taken to reduce the ingress of ambient heat into the tank shell, some heating from ambient sources will occur leading to boiling of a small amount of the liquid and consequential pressure rise (which should be well within the capacity of the shell to withstand). Most T75 tank containers are fitted with a special automatic bleed valve to allow this low level pressure to drain away during transport. It may be switched on and off manually. When switched off, this minor rise in pressure is not automatically drained off. The latest edition of the IMDG Code in force at the time of preparation of this pamphlet does not contain any restriction concerning leaving the valve in an operational condition though it is possible to interpret paragraph 7.1.8.1.3 of the IMDG Code to mean that this valve should be closed when T75 tank containers are carried on board sea-going vessels. 5.6.6 Vacuum Connection 5.6.6.1 There will be a connection on the outer surface of the vacuum jacket to which gauges may be temporarily attached to measure the vacuum level and/or to attach a pump to draw a near perfect vacuum between the jacket and the shell. The location of this connection will varies from design to design. 5.6.7 Formation of Ice on Fittings and Pipework 5.6.7.1 It is possible for ice to form on fittings and pipework on T75 tank containers even in the hottest and most arid of conditions. The formation of ice in this way is not necessarily an indication that the tank container is leaking. The ice is formed from water vapour in the air condensing on the pipework, etc. 5.7 Fixtures 5.7.1 Walkways 5.7.1.1 A light weight walkway usually constructed of perforated aluminium plate is often fitted on top of tank containers. It can be held in place by connections to one or both of the top side rails or to brackets attached to the end frame and pressure vessel. 5.7.1.2 Where the tank container is fitted with a walkway or access platform on top of the tank container. It should be of adequate dimensions in a single plane and with no tripping hazards and constructed of a non slip surface material allowing suitable drainage. 5.7.1.3 ITCO recommends that it should be at least 460mm wide with slope less than 10° and be positioned to give safe access to the manway lid and sampling areas. Those tank containers that have a small diameter shell and require step down to access such areas should also have adequate flooring at the lower level. Note: The walkway and supporting structure, including top side rails, are lightweight and only designed to support two persons. Over crowding the walkway or excessive loading can result in it failing with a severe risk of personnel falling. Page 20 ©ICHCA International Limited
ICHCA International Safety Panel Briefing Pamphlet No 30 5.7.2 Access Ladders 5.7.2.1 The tank containers shown in this pamphlet generally have an access ladder built into the end frame as shown in Picture 40 and Picture 41. It should be remembered that the ladder should only be used when suitable steps or an access platform adjacent to the tank container is not available. See section 13. 5.7.3 Insulation Picture 40 Picture 41 5.7.3.1 Insulated tank containers will generally be enclosed in a preformed insulation material or wrapped in insulation matting. Both types of insulation will be then covered with either a GPR, stainless steel or an aluminium cladding jacket. Note: The cladding / insulation material is not designed to withstand a person standing on it. Picture 42 is an example of the warning signs typically fitted. Standing on the cladding may damage it and there is a risk of falling. 5.7.4 Heating and Cooling 5.7.4.1 The majority of insulated tank containers will have some form of heating capability. The principle means of applying the heat is by steam, hot water or hot glycol being piped through heating coils welded directly onto the exterior of the barrel. Inlet and outlet connections should be clearly marked (see Picture 43). Picture 42 5.7.4.2 Hot water/hot glycol heating systems Picture 43 have a covered trough filled with the appropriate liquid. An electrical heating coil is immersed in the trough and a thermostat switches on an electric pump to circulate the heated liquid through the steam coil. Some tanks have a separate coil for the heated liquid. Glycol is often preferred because for example it has a lower freezing temperature than water. Page 21 ©ICHCA International Limited
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Safe Handling of Tank Containers - ITCO

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