Business segment reporting (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2016 USD ($) Segments	Oct. 31, 2015 USD ($)	Oct. 31, 2016 USD ($)	Oct. 31, 2015 USD ($)
Segment reporting
Number of reportable segments | Segments	1
Net sales	$ 25,302	$ 46,950	$ 71,230	$ 92,374
Gross profit	3,697	14,315	8,669	19,796
(Loss) income from operations	(1,037)	7,521	$ (7,382)	1,421
Piping Systems [Member]
Segment reporting
Segment reporting information, description of Products and Services			Piping Systems engineers, designs, manufactures and sells specialty piping, leak detection and location systems
Net sales	25,302	46,950	$ 71,230	92,374
Gross profit	3,697	14,315	8,669	19,796
(Loss) income from operations	640	9,721	(1,775)	7,470
Corporate Segment [Member]
Segment reporting
(Loss) income from operations	$ (1,677)	$ (2,200)	$ (5,607)	$ (6,049)