Intangible Assets

12 Months Ended

Dec. 31, 2012

Intangible Assets

9.    Intangible Assets

Intangible assets principally comprise technology/technical know-how, tradenames and customer relationships. At December 31, intangible assets were as follows:

(Stated in millions)
	2012						2011
	Gross Book Value		Accumulated Amortization		Net Book Value		Gross Book Value		Accumulated Amortization		Net  Book Value
Technology/Technical Know-How	$	1,967	$	474	$	1,493	$	1,875	$	341	$	1,534
Tradenames		1,647		188		1,459		1,677		131		1,546
Customer Relationships		2,115		312		1,803		1,954		209		1,745
Other		369		322		47		356		299		57
	$	6,098	$	1,296	$	4,802	$	5,862	$	980	$	4,882

Amortization expense was $331 million in 2012, $324 million in 2011 and $190 million in 2010.

The weighted average amortization period for all intangible assets is approximately 20 years.

Amortization expense for the subsequent five years is estimated to be as follows: 2013 – $325 million, 2014 – $320 million, 2015 – $311 million, 2016 – $295 million and 2017 – $284 million.