Note 4 - Revenue Recognition - Revenues by Revenue Class (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2024	Oct. 31, 2023	Oct. 31, 2024	Oct. 31, 2023
Sales by product	$ 41,563	$ 45,690	$ 113,397	$ 110,489
Sales by product, percent	100.00%	100.00%	100.00%	100.00%
Product [Member] | Transferred at Point in Time [Member]
Sales by product	$ 3,622	$ 2,553	$ 9,670	$ 7,541
Sales by product, percent	8.00%	5.00%	8.00%	7.00%
Specialty Piping Systems And Coating [Member] | Transferred at Point in Time Using Input Method [Member]
Sales by product	$ 12,268	$ 18,641	$ 35,020	$ 41,779
Sales by product, percent	30.00%	41.00%	31.00%	38.00%
Specialty Piping Systems And Coating [Member] | Transferred at Point in Time Using Output Method [Member]
Sales by product	$ 25,673	$ 24,496	$ 68,707	$ 61,169
Sales by product, percent	62.00%	54.00%	61.00%	55.00%