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| <periodOfReport> 2020-06-17 </periodOfReport> |
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| <issuer> |
| | <issuerCik> 0001540947 </issuerCik> |
| | <issuerName> EQM Midstream Partners, LP </issuerName> |
| | <issuerTradingSymbol> EQM </issuerTradingSymbol> |
| | </issuer> |
| <reportingOwner> |
| | <reportingOwnerId> |
| | | <rptOwnerCik> 0001184622 </rptOwnerCik> |
| | | <rptOwnerName> BRYSON MICHAEL A </rptOwnerName> |
| | | </reportingOwnerId> |
| | <reportingOwnerAddress> |
| | | <rptOwnerStreet1> 2200 ENERGY DRIVE </rptOwnerStreet1> |
| | | <rptOwnerStreet2></rptOwnerStreet2> |
| | | <rptOwnerCity> CANONSBURG </rptOwnerCity> |
| | | <rptOwnerState> PA </rptOwnerState> |
| | | <rptOwnerZipCode> 15317 </rptOwnerZipCode> |
| | | <rptOwnerStateDescription></rptOwnerStateDescription> |
| | | </reportingOwnerAddress> |
| | <reportingOwnerRelationship> |
| | | <isDirector> 1 </isDirector> |
| | | <isOfficer> 0 </isOfficer> |
| | | <isTenPercentOwner> 0 </isTenPercentOwner> |
| | | <isOther> 0 </isOther> |
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| | </reportingOwner> |
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| <value> 1175 </value> |
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| | | <ownershipNature> |
| <directOrIndirectOwnership> |
| <value> I </value> |
| </directOrIndirectOwnership> |
| <natureOfOwnership> |
| <value> Kathryn F. Bryson Revocable Trust </value> |
| </natureOfOwnership> |
| </ownershipNature> |
| | | </nonDerivativeTransaction> |
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| <value> Deferred Compensation - Phantom Units </value> |
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| <underlyingSecurityTitle> |
| <value> Common Units </value> |
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| <value> 18412 </value> |
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| <footnotes> |
| | <footnote id="F1"> Pursuant to that certain Agreement and Plan of Merger, dated February 26, 2020, by and between the Issuer, Equitrans Midstream Corporation ("ETRN"), EQGP Services, LLC, EQM LP Corporation, and LS Merger Sub, LLC, (the "Merger Agreement"), ETRN acquired all of the outstanding common units representing limited partner interests in the Issuer (the "Common Units") that ETRN and its subsidiaries do not already own. Upon consummation of the merger, each outstanding Common Unit, other than Common Units owned by ETRN or its subsidiaries, was converted into the right to receive 2.44 shares of ETRN common stock, no par value, and all fractional shares of ETRN common stock to which a holder of Common Units otherwise would have been entitled was aggregated and the resulting fractional shares were rounded up to the nearest whole share of ETRN common stock (collectively, the "Merger Consideration"). </footnote> |
| | <footnote id="F2"> Each Phantom Unit is the economic equivalent of one Common Unit. </footnote> |
| | <footnote id="F3"> Pursuant to the Merger Agreement, as of the effective time of the merger, each Phantom Unit vested in full and automatically converted into the right to receive, with respect to each Common Unit subject thereto, the Merger Consideration. </footnote> |
| | </footnotes> |
| <remarks></remarks> |
| <ownerSignature> |
| | <signatureName> /s/ Tobin M. Nelson, Attorney-in-Fact for Michael A. Bryson </signatureName> |
| | <signatureDate> 2020-06-17 </signatureDate> |
| | </ownerSignature> |
| </ownershipDocument> |