Property, Plant and Equipment—Net

Property, plant and equipment—net consists of the following:



	December 31,
	2017		2016
	(in millions)
Land	$	71	$	69
Machinery and equipment	12,070		11,664
Buildings and improvements	882		878
Construction in progress	223		280
Property, plant and equipment⁽¹⁾	13,246		12,891
Less: Accumulated depreciation and amortization	4,071		3,239
Property, plant and equipment—net	$	9,175	$	9,652

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⁽¹⁾	As of December 31, 2017 and 2016, we had property, plant and equipment that was accrued but unpaid of approximately $46 million and $225 million, respectively. These amounts included accruals related to our capacity expansion projects of $185 million as of December 31, 2016.

Depreciation and amortization related to property, plant and equipment was $848 million, $607 million and $444 million in 2017, 2016 and 2015, respectively.

Plant turnarounds—Scheduled inspections, replacements and overhauls of plant machinery and equipment at our continuous process manufacturing facilities during a full plant shutdown are referred to as plant turnarounds. The expenditures related to turnarounds are capitalized in property, plant and equipment when incurred. The following is a summary of capitalized plant turnaround costs:



	Year ended December 31,
	2017			2016			2015
	(in millions)
Net capitalized turnaround costs at beginning of the year	$	206		$	220		$	153
Additions	100			74			135
Depreciation	(102		)	(89		)	(65		)
Effect of exchange rate changes	4			1			(3		)
Net capitalized turnaround costs at end of the year	$	208		$	206		$	220

Scheduled replacements and overhauls of plant machinery and equipment include the dismantling, repair or replacement and installation of various components including piping, valves, motors, turbines, pumps, compressors, heat exchangers and the replacement of catalysts when a full plant shutdown occurs. Scheduled inspections are also conducted during full plant shutdowns, including required safety inspections which entail the disassembly of various components such as steam boilers, pressure vessels and other equipment requiring safety certifications. Internal employee costs and overhead amounts are not considered turnaround costs and are not capitalized.