Note 4 - Revenue Recognition - Revenues by Revenue Class (Details) - USD ($) $ in Thousands	3 Months Ended
Apr. 30, 2023	Apr. 30, 2022
Sales by product	$ 29,657	$ 31,222
Sales by product, percent	100.00%	100.00%
Product [Member] \| Transferred at Point in Time [Member]
Sales by product	$ 2,842	$ 2,912
Sales by product, percent	9.00%	9.00%
Specialty Piping Systems And Coating [Member] \| Transferred at Point in Time Using Input Method [Member]
Sales by product	$ 10,338	$ 10,617
Sales by product, percent	35.00%	34.00%
Specialty Piping Systems And Coating [Member] \| Transferred at Point in Time Using Output Method [Member]
Sales by product	$ 16,477	$ 17,693
Sales by product, percent	56.00%	57.00%

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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+ Details