In our ’Tank coatings and your ticket to trade’ webinar, Chevron Shipping hull and coatings engineer Johnny Eliasson and Safinah Group coating consultant Michael Aamodt considered the challenges of tank coatings for challenging cargoes
The impact of developments in tank coating technology and application cannot be understated, the panellists said. Almost every generation of tanker design gains an advantage from newly developed coatings but coatings advancements can also bring challenges.
In a poll, webinar attendees were evenly split on how tank coating developments have impacted their operations. Asked whether useful life of tank coatings has increased over the last 5-10 years, 36% said coatings lifetimes had increased, but the same number, 36%, said coatings lifetimes had shortened. The other 28% of respondents found little or no change in coatings lifetimes.
Chevron Shipping’s Mr Eliasson offered detail on the types of coatings used onboard different tanker types, noting that while much focus in the trade is placed on product tanker and chemical carrier coatings, the crude oil tanker sector offers its own set of coatings challenges. For epoxy-coated crude oil tanks, Mr Eliasson said the main concern was the temperature gradient within the cargo tank.
“The oil temperature increases deeper down in the tank,” he said.
Mr Eliasson explained that different cargoes also have different impacts on tank coatings, listing EDC, ethanol, methanol, styrene, di-chloropropene, crude edible oils, binyl acetate monomer and latex among a list of cargoes that are particularly challenging for coatings.
“It is important to know the source (of the cargo) in order to establish the suitable stainless steel for carriage,” he said, noting that stainless steel tanks can be damaged from pitting by high-strength phosphoric acid. “Knowing about the cargo is very important.... To know is to succeed," he said.
Simlarly for cargo handling, Mr Eliasson said that for critical safety and effective handling, all the cargo characteristics during loading, during the voyage and during discharge must be thoroughly understood.
An era of growth in the chemical seaborne trade has been characterised by an increase in vessel size, and larger vessels flex more and increase the stress on coatings Safinah Group’s Mr Aamodt said in his presentation.
The chemical seaborne trade has had an average 7% annual growth that has been “mainly driven by the growth of inorganic chemicals,” he said.
An increase in the methanol trade has also been a challenge, given its demanding carriage requirements, he said.
Mr Aamodt also highlighted the cleaning challenges of cargoes such as styrene, benzene, MtBE, EDC, vegetable oils and CPP which are all becoming more prevalent.
From an owner/operator perspective, advantages from development of new coatings include allowance for a greater number of cargoes, fewer cargo restrictions and quicker cleaning.
“Maximising earning and minimising downtime has led to operators and owners requesting a new generation of tank coatings that better fit their operational needs,” Mr Aamodt said, noting that there also have been developments in tank cleaning techniques, with better analytical tools available to match the requirements of higher specifications from the cargoes.
Asked in a poll about their experiences with cargo tank cleaning, more than a third of webinar attendees (34%) noted it was getting more difficult, while nearly half (48%) reported cleaning difficulties had gotten no better or worse. The remainder (18%) reported that cleaning was getting easier.
Asked what has been the time impact on cleaning after an effective ban on methanol wash, more than 70% of respondents said cleaning time required had increased by 12 hours or more, a further 15% said 1-12 hours had been added and 15% of respondents said they had seen no difference in cleaning times required.
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Panellists (left to right): Chevron Shipping hull & coatings engineer Johnny Eliasson and Safinah Group coating consultant Michael Aamodt.