<SUBMISSION>
<ACCESSION-NUMBER>0001187049-03-000002
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20030617
<FILING-DATE>20030618
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>WELLENDORF DON R
<CIK>0001187049
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-16335
<FILM-NUMBER>03748389
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>ONE WILLIAMS CENTER SUITE 3500
<CITY>TULSA
<STATE>OK
<ZIP>74172
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>WILLIAMS ENERGY PARTNERS L P
<CIK>0001126975
<ASSIGNED-SIC>4610
<IRS-NUMBER>731599053
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>ONE WILLIAMS CENTER
<CITY>TULSA
<STATE>OK
<ZIP>74172
<PHONE>9185732000
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>ONE WILLIAMS CENTER
<CITY>TULSA
<STATE>OK
<ZIP>74171
</MAIL-ADDRESS>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-06-17</periodOfReport>
    <issuer>
        <issuerCik>0001126975</issuerCik>
        <issuerName>WILLIAMS ENERGY PARTNERS L P</issuerName>
        <issuerTradingSymbol>WEG</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001187049</rptOwnerCik>
            <rptOwnerName>WELLENDORF DON R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>CEO and President</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeSecurity><securityTitle><value>Common Units</value></securityTitle><transactionDate><value>2003-06-17</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>6358</value></transactionShares><transactionValue><value>47.27</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>12554</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></nonDerivativeSecurity><nonDerivativeSecurity><securityTitle><value>Common Units</value></securityTitle><transactionDate><value>2003-06-17</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>F</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>2034</value></transactionShares><transactionValue><value>47.27</value></transactionValue><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>10520</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></nonDerivativeSecurity><derivativeSecurity><securityTitle><value>Phantom Units</value><footnoteId id="F1"/><footnoteId id="F2"/></securityTitle><conversionOrExercisePrice><value>47.27</value></conversionOrExercisePrice><transactionDate><value>2003-06-17</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>6358</value></transactionShares><transactionValue><value>47.27</value></transactionValue><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2003-06-17</value></exerciseDate><expirationDate><value>2003-06-17</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Units</value></underlyingSecurityTitle><underlyingSecurityShares><value>6358</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>19300</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeSecurity><derivativeSecurity><securityTitle><value>Phantom Units</value><footnoteId id="F1"/><footnoteId id="F3"/></securityTitle><conversionOrExercisePrice><value>47.27</value></conversionOrExercisePrice><transactionDate><value>2003-06-17</value></transactionDate><transactionCoding><transactionFormType>5</transactionFormType><transactionCode>D</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>38600</value><footnoteId id="F4"/></transactionShares><transactionValue><value>47.27</value></transactionValue><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2003-06-17</value></exerciseDate><expirationDate><value>2003-06-17</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Units</value></underlyingSecurityTitle><underlyingSecurityShares><value>38600</value><footnoteId id="F4"/></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeSecurity><footnotes><footnote id="F1">Inaccurately described in previous filings as Deferred Units.</footnote><footnote id="F2">Represents conversion of phantom units to common units exempt pursuant to Rule 16b-6(b). </footnote><footnote id="F3">Represents settlement of phantom units for cash exempt pursuant to Rule 16b-3(e).</footnote><footnote id="F4">Phantom units vested at 200% due to a change-in-control of the issuer.</footnote></footnotes><ownerSignature><signatureName>Don R. Wellendorf</signatureName><signatureDate>2003-06-18</signatureDate></ownerSignature></ownershipDocument>

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</TEXT>
</DOCUMENT>
</SUBMISSION>
