Segment Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Mar. 31, 2014
Segment Reporting Information [Line Items]
Net sales	$ 31,544,474	$ 26,310,369	$ 59,448,996	$ 55,892,512
Interest & other income	15,282	15,500	30,534	31,007
Earnings before income taxes	1,139,359	47,757	1,062,096	1,202,206
Total assets	71,201,761		71,201,761		72,284,399
Operating Segments
Segment Reporting Information [Line Items]
Operating profit (loss)	1,735,000	407,000	2,103,000	2,235,000
Total assets	62,848,000		62,848,000		56,103,000
Operating Segments | Coil
Segment Reporting Information [Line Items]
Net sales	21,275,000	14,678,000	39,182,000	31,841,000
Operating profit (loss)	410,000	(700,000)	6,000	(522,000)
Total assets	26,667,000		26,667,000		22,308,000
Operating Segments | Tubular
Segment Reporting Information [Line Items]
Net sales	10,269,000	11,632,000	20,267,000	24,052,000
Operating profit (loss)	1,325,000	1,107,000	2,097,000	2,757,000
Total assets	36,181,000		36,181,000		33,795,000
Corporate and other
Segment Reporting Information [Line Items]
Corporate expenses	611,000	375,000	1,072,000	1,064,000
Total assets	$ 8,354,000		$ 8,354,000		$ 16,181,000