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Bottom loading

Already for many years, bottom loading in the fuel industry is applied according to one worldwide adopted standard. This is the API RP 10004 (American Petroleum Institute Recommended Practice). This standard safeguards the quick and safe simultaneous loading of various fuels. Standard couplers and overfill devices make this possible. The closed system enables the recovery of displaced vapours.

Also in the chemical industry there is a clear tendency to convert from top to bottom loading. However it still lacks a standard comparable with the API RP 1004. This has the following reasons.

Bottom loading: fuels versus chemicals

Firstly, there are only five primary liquids in the petroleum industry. They all have the same broad application as fuels. Secondly, the tankers are specifically designed and built to enable to recover the vapours and monitor the levels. The equipment at the loading bays is broadly similar and it has to be able to ‘talk’ to any tanker that turns up.

The chemical industry has many thousands of combinations of liquids. The consequence being that the tankers are largely hired for the trip. They are not specifically suited to the liquid transported. Therefore vapour recovery is rarely built into the tanker and high-level devices are not used at all. This means that the onus for supplying the safe system falls to the company loading the tanker.

Another bonus of petroleum bottom loading is speed. Up to 6 arms can be connected to a tanker at one time and loaded together into various compartments. Chemical tankers tend to have single compartments; so only one connection is needed.