SIXTH AMENDMENT TO SECOND AMENDED AND RESTATED LOAN AND SECURITY AGREEMENT

THIS SIXTH AMENDMENT TO SECOND AMENDED AND RESTATED LOAN AND SECURITY AGREEMENT (“Sixth Amendment”) is made as of this 29th day of July, 2013, by and among BANK OF AMERICA, N.A., a national banking association (“Bank of America”) with an office at 135 South LaSalle Street, 4th Floor, Chicago, Illinois 60603, individually as a Lender and as Agent (“Agent”) for itself and any other financial institution which is or becomes a party hereto (each such financial institution, including Bank of America, is referred to hereinafter individually as a “Lender” and collectively as the “Lenders”), the LENDERS and MFRI, INC., a Delaware corporation (“MFRI”), MIDWESCO FILTER RESOURCES, INC., a Delaware corporation (“Midwesco”), PERMA-PIPE, INC., a Delaware corporation (“Perma-Pipe”), TC NILES CORPORATION (f/k/a THERMAL CARE, INC.), a Delaware corporation (“Thermal Care”), TDC FILTER MANUFACTURING, INC., a Delaware corporation (“TDC”), MM NILES CORPORATION (f/k/a MIDWESCO MECHANICAL AND ENERGY, INC.), a Delaware corporation (“Mechanical”) and PERMA-PIPE INTERNATIONAL COMPANY, LLC, a Delaware limited liability company (“Perma-Pipe International”) and PERMA-PIPE CANADA, INC., a Delaware corporation (“Perma-Pipe Canada”). Capitalized terms used in this Agreement have the meanings assigned to them in Appendix A, General Definitions. Accounting terms not otherwise specifically defined herein shall be construed in accordance with GAAP consistently applied. MFRI, Midwesco, Perma-Pipe, Thermal Care, TDC, Mechanical, Perma-Pipe International and Perma-Pipe Canada are sometimes hereinafter referred to individually as a “Borrower” and collectively as “Borrowers”.

WHEREAS, Borrowers, Agent, and the Lender signatories thereto hereto entered into that certain Second Amended and Restated Loan and Security Agreement dated April 30, 2012 as amended by a certain First Amendment to Second Amended and Restated Loan and Security Agreement by and among Borrowers, Agent and the Lender signatories thereto dated June 8, 2012, by a certain Second Amendment to Second Amended and Restated Loan and Security Agreement by and among Borrowers, Agent and the Lender signatures thereto dated October 12, 2012, by a certain Third Amendment to Second Amended and Restated Loan and Security Agreement by and among Borrowers, Agent and the Lender signatures thereto dated March 15, 2013, and by a certain Fourth Amendment to Second Amended and Restated Loan and Security Agreement dated April 25, 2013 and by a certain Fifth Amendment to Second Amended and Restated Loan and Security Agreement dated as of June 13, 2013 (said Second Amended and Restated Loan and Security Agreement, as amended from time to time, the “Loan Agreement”);

NOW, THEREFORE, in consideration of the following terms and conditions, the parties agreed as follows:

“Availability Threshold - $3,500,000.

Revolving Credit Maximum Amount - $25,000,000 minus the outstanding principal balance of the Term Loan.”