Quarterly report pursuant to Section 13 or 15(d)

Revenue Recognition - Revenue Disaggregated by Product Line and Geographic Area (Detail)

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Revenue Recognition - Revenue Disaggregated by Product Line and Geographic Area (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Disaggregation Of Revenue [Line Items]        
Net sales $ 21,441 $ 17,224 $ 50,992 $ 38,075
Heat Transfer Equipment [Member]        
Disaggregation Of Revenue [Line Items]        
Net sales 6,173 4,654 10,331 10,983
Vacuum Equipment [Member]        
Disaggregation Of Revenue [Line Items]        
Net sales 7,842 4,889 25,058 11,412
All Other [Member]        
Disaggregation Of Revenue [Line Items]        
Net sales 7,426 7,681 15,603 15,680
Asia [Member]        
Disaggregation Of Revenue [Line Items]        
Net sales 1,876 2,599 4,625 5,964
Canada [Member]        
Disaggregation Of Revenue [Line Items]        
Net sales 3,473 1,844 15,123 3,199
Middle East [Member]        
Disaggregation Of Revenue [Line Items]        
Net sales 464 1,015 899 1,935
South America [Member]        
Disaggregation Of Revenue [Line Items]        
Net sales 68 441 192 570
U.S. [Member]        
Disaggregation Of Revenue [Line Items]        
Net sales 15,073 11,146 28,526 25,975
All Other [Member]        
Disaggregation Of Revenue [Line Items]        
Net sales $ 487 $ 179 $ 1,627 $ 432