Note H - Segment Information - Segment Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Total Net Sales	$ 28,150,817	$ 43,326,080	$ 109,121,717	$ 144,951,427
Interest expense	2,463	1,792	2,463	17,545
Interest & other income	(4,370)	(6,275)	(15,075)	(75,325)
Total earnings (loss) before taxes	(1,145,553)	880,867	(2,908,411)	8,289,004
Segment assets	84,229,802		84,229,802		$ 86,601,982
Coil [Member]
Total Net Sales	21,001,358	28,730,992	77,603,435	94,688,636
Tubular [Member]
Total Net Sales	7,149,459	14,595,088	31,518,282	50,262,791
Operating Segments [Member]
Operating profit (loss)	(561,000)	1,394,000	(1,095,000)	10,195,000
Segment assets	61,626,000		61,626,000		74,624,000
Operating Segments [Member] | Coil [Member]
Total Net Sales	21,001,000	28,731,000	77,604,000	94,688,000
Operating profit (loss)	(93,000)	744,000	575,000	5,847,000
Segment assets	35,272,000		35,272,000		43,104,000
Operating Segments [Member] | Tubular [Member]
Total Net Sales	7,150,000	14,595,000	31,518,000	50,263,000
Operating profit (loss)	(468,000)	650,000	(1,670,000)	4,348,000
Segment assets	26,354,000		26,354,000		31,520,000
Corporate, Non-Segment [Member]
Corporate expenses	587,000	$ 517,000	1,826,000	$ 1,963,000
Segment assets	$ 22,604,000		$ 22,604,000		$ 11,978,000