<SEC-DOCUMENT>0000914122-13-000054.txt : 20130802
<SEC-HEADER>0000914122-13-000054.hdr.sgml : 20130802
<ACCEPTANCE-DATETIME>20130802104921
ACCESSION NUMBER:		0000914122-13-000054
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20130731
FILED AS OF DATE:		20130802
DATE AS OF CHANGE:		20130802

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MFRI INC
		CENTRAL INDEX KEY:			0000914122
		STANDARD INDUSTRIAL CLASSIFICATION:	INDUSTRIAL & COMMERCIAL FANS & BLOWERS & AIR PURIFYING EQUIP [3564]
		IRS NUMBER:				363922969
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0131

	BUSINESS ADDRESS:	
		STREET 1:		7720 LEHIGH AVE
		CITY:			NILES
		STATE:			IL
		ZIP:			60714
		BUSINESS PHONE:		8479661000

	MAIL ADDRESS:	
		STREET 1:		7720 LEHIGH AVE
		CITY:			NILES
		STATE:			IL
		ZIP:			60714

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MIDWESCO FILTER RESOURCES INC
		DATE OF NAME CHANGE:	19970402

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SCHWARTZ STEPHEN B
		CENTRAL INDEX KEY:			0001073261

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-32530
		FILM NUMBER:		131005167

	MAIL ADDRESS:	
		STREET 1:		7720 N. LEHIGH AVENUE
		CITY:			NILES
		STATE:			IL
		ZIP:			60714
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-07-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000914122</issuerCik>
        <issuerName>MFRI INC</issuerName>
        <issuerTradingSymbol>MFRI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001073261</rptOwnerCik>
            <rptOwnerName>SCHWARTZ STEPHEN B</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>7720 N. LEHIGH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NILES</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60714</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Deferred Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2013-07-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>461</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>461</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3984</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Deferred Stock Units earned by the reporting person by elective deferral of director retainer, pursuant to the companys Deferred Stock Purchase Plan.  The Deferred Stock Units are payable to the reporting person in Common Stock on a one-for-one basis, upon separation of service as a meember of the Board.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Stephen B Schwartz</signatureName>
        <signatureDate>2013-08-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
