COLUMN-China's metal imports; key themes for 2013: Andy Home

 (Andy Home is a Reuters columnist. The opinions expressed are his own)

By Andy Home

LONDON, Feb 26 (Reuters) - One month's data does not a trend make. That useful statistical maxim holds particularly true of Chinese import figures at the start of any year because of the variable that is the timing of the Lunar New Year holidays.

However, with one or two exceptions, January's metal trade figures merely confirmed trends that were already emerging at the end of last year.

One that is likely to be a key theme of China's trade this year is the gradual shift away from refined metal towards raw materials imports.

That reflects the continued build-out of processing capacity in China, an evolution that is most advanced in the aluminium sector but which is becoming ever more prominent a feature across the industrial metals spectrum.

Shorter-term arbitrage fluctuations interact with this underlying dynamic with the potential to accelerate it or slow it at any given time.

As China becomes increasingly self-sufficient at the refined metal stage of the supply chain, the question of potential export flows will become increasingly important.

Again, aluminium is a case in point. What the country imports in primary metal form is dwarfed by what it exports as fabricated product.

It is an extreme example. But this year, for the first time ever, it looks as if the copper market will have to factor in a steady counter-flow of shipments out of China.

Net imports of primary aluminium were 2,350 tonnes last month, the lowest monthly level since November 2011.

Negative arbitrage between London and Shanghai is a key consideration but it is merely accelerating a longer-term trend.

The last time China was a major importer of primary aluminium was in the first half of 2009, when the arbitrage was distorted by "strategic" purchases of metal by the Chinese government.

The country, meanwhile, remains a steady net exporter both of alloy and semi-manufactured products.

The latter have held steady in a 220,000-240,000-tonne per month range since the middle of last year with January's 230,000 tonnes not disrupting that trend.

However, product exports should be watched closely over the coming months given expectations that rising domestic surplus may result in accelerated outflows.