Note 4 - Revenue Recognition - Revenues by Revenue Class (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2024	Jul. 31, 2023	Jul. 31, 2024	Jul. 31, 2023
Sales by product	$ 37,513	$ 35,141	$ 71,834	$ 64,798
Sales by product, percent	100.00%	100.00%	100.00%	100.00%
Product [Member] | Transferred at Point in Time [Member]
Sales by product	$ 2,795	$ 2,146	$ 6,048	$ 4,988
Sales by product, percent	7.00%	7.00%	8.00%	7.00%
Specialty Piping Systems And Coating [Member] | Transferred at Point in Time Using Input Method [Member]
Sales by product	$ 12,613	$ 12,801	$ 22,752	$ 23,139
Sales by product, percent	34.00%	36.00%	32.00%	36.00%
Specialty Piping Systems And Coating [Member] | Transferred at Point in Time Using Output Method [Member]
Sales by product	$ 22,105	$ 20,194	$ 43,034	$ 36,671
Sales by product, percent	59.00%	57.00%	60.00%	57.00%