Note G - Segment Information - Segment Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2019	Mar. 31, 2018
Total Net Sales	$ 39,995,580	$ 53,432,029	$ 80,970,900	$ 101,625,347
Interest & other income	(4,370)	(6,275)	(10,705)	(69,050)
Total earnings (loss) before taxes	(2,032,129)	2,645,625	(1,762,858)	7,408,138
Segment assets	81,927,595		81,927,595		$ 86,602,000	$ 86,601,982
Coil [Member]
Total Net Sales	28,420,609	34,828,444	56,602,077	65,957,644
Tubular [Member]
Total Net Sales	11,574,971	18,603,585	24,368,823	35,667,703
Operating Segments [Member]
Operating profit (loss)	(1,422,000)	3,301,000	(533,000)	8,801,000
Segment assets	62,004,000		62,004,000		74,624,000
Operating Segments [Member] | Coil [Member]
Total Net Sales	28,421,000	34,828,000	56,602,000	65,957,000
Operating profit (loss)	324,000	1,925,000	668,000	5,103,000
Segment assets	34,633,000		34,633,000		43,104,000
Operating Segments [Member] | Tubular [Member]
Total Net Sales	11,575,000	18,604,000	24,369,000	35,668,000
Operating profit (loss)	(1,746,000)	1,376,000	(1,201,000)	3,698,000
Segment assets	27,371,000		27,371,000		31,520,000
Corporate, Non-Segment [Member]
Corporate expenses	614,000	$ 661,000	1,241,000	$ 1,462,000
Segment assets	$ 19,924,000		$ 19,924,000		$ 11,978,000