Revenue recognition (Tables)

6 Months Ended

Jul. 31, 2018

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

	Three Months Ended July 31,						Six Months Ended July 31,
	2018			2017			2018			2017
	Sales	% to Total		Sales	% to Total		Sales	% to Total		Sales	% to Total
Products	2,578	8	%	1,995	7	%	5,007	8	%	3,326	7	%
Specialty Piping Systems and Coating
Revenue recognized under input method	9,807	30	%	14,138	53	%	20,909	34	%	23,254	46	%
Revenue recognized under output method	19,940	62	%	10,719	40	%	35,298	58	%	23,773	47	%
Total	32,325	100	%	26,852	100	%	61,214	100	%	50,353	100	%

Contract with Customer, Asset and Liability

The following tables set forth the activity in contract assets and liabilities. The Company expects to recognize the remaining balance within one year.

	Contract Assets
Balance January 31, 2018		$1,502
Costs and gross profit recognized during the period for uncompleted contracts from the prior period	(1,085		)
Costs and deferred gross profit incurred on uncompleted contracts not billed at the end of the current period	1,417
Closing Balance at April 30, 2018	1,834
Costs and gross profit recognized during the period for uncompleted contracts from the prior period	(1,395		)
Costs and deferred gross profit incurred on uncompleted contracts not billed at the end of the current period	1,575
Closing Balance at July 31, 2018		$2,014

	Contract Liabilities
Balance January 31, 2018		$1,967
Revenue recognized during the period for uncompleted contracts from the prior period	(1,810		)
New contracts entered into that are uncompleted at the end of the current period	413
Closing Balance at April 30, 2018	570
Revenue recognized during the period for uncompleted contracts from the prior period	(422		)
New contracts entered into that are uncompleted at the end of the current period	398
Closing Balance at July 31, 2018		$546