Subsequent events (Notes)	12 Months Ended
Jan. 31, 2013
Subsequent Events [Abstract]
Subsequent events [Text Block]	Subsequent events Sale of assets. Subsequent to the year-end, on April 26, 2013, the Company announced the signing of a definitive agreement to sell most of the domestic assets of its subsidiary Thermal Care, Inc. to a subsidiary of IPEG, Inc. The transaction closed April 30, 2013. Industrial process cooling designs, manufactures and sells industrial process cooling, including chillers, cooling towers, plant circulating systems, and related accessories for use in industrial process applications. Upon closing the Company transferred the applicable assets, liabilities and employees of the business to a subsidiary of IPEG, Inc. The acquiring company has signed a leased for the current office space and production facilities Thermal Care currently occupies. The Company estimates that the taxable gain will be approximately $11.6 million and based on that estimate approximately $3 million of the valuation allowance recorded on the domestic DTAs will be reversed and taken into income in the first quarter of 2013. Disposition of Thermal Care, Inc. will enable MFRI, Inc. to focus on its two principal segments: piping systems and filtration products. The Company included Thermal Care, Inc. in its consolidated results of the industrial processing cooling segment in continuing operations as of January 31, 2013 since the decision to sell the assets occurred after that time. In future periods industrial process cooling will be reported as a discontinued operation. Bank amendments. The third amendment to the loan agreement executed March 15, 2013 extended the maturity date of the loan from November 30, 2013 to November 30, 2016. The fixed charge coverage ratio covenant beginning February 1, 2013 will be calculated on a domestic consolidated basis instead of a world-wide consolidated basis. The fourth amendment to the loan agreement executed April 25,2013 changed the excess availability required for the periods ended February and March 31, 2013 and approved the sale of Thermal Care assets.

Subsequent events

Sale of assets. Subsequent to the year-end, on April 26, 2013, the Company announced the signing of a definitive agreement to sell most of the domestic assets of its subsidiary Thermal Care, Inc. to a subsidiary of IPEG, Inc. The transaction closed April 30, 2013. Industrial process cooling designs, manufactures and sells industrial process cooling, including chillers, cooling towers, plant circulating systems, and related accessories for use in industrial process applications.

Upon closing the Company transferred the applicable assets, liabilities and employees of the business to a subsidiary of IPEG, Inc. The acquiring company has signed a leased for the current office space and production facilities Thermal Care currently occupies. The Company estimates that the taxable gain will be approximately $11.6 million and based on that estimate approximately $3 million of the valuation allowance recorded on the domestic DTAs will be reversed and taken into income in the first quarter of 2013.

Disposition of Thermal Care, Inc. will enable MFRI, Inc. to focus on its two principal segments: piping systems and filtration products. The Company included Thermal Care, Inc. in its consolidated results of the industrial processing cooling segment in continuing operations as of January 31, 2013 since the decision to sell the assets occurred after that time. In future periods industrial process cooling will be reported as a discontinued operation.

Bank amendments. The third amendment to the loan agreement executed March 15, 2013 extended the maturity date of the loan from November 30, 2013 to November 30, 2016. The fixed charge coverage ratio covenant beginning February 1, 2013 will be calculated on a domestic consolidated basis instead of a world-wide consolidated basis. The fourth amendment to the loan agreement executed April 25,2013 changed the excess availability required for the periods ended February and March 31, 2013 and approved the sale of Thermal Care assets.