UNITED STATES SECURITIES AND EXCHANGE COMMISSION Form 10-K FOR THE FISCAL YEAR ENDED DECEMBER 31, 2020 Washington, D.C. 20549 ☑ ☐ OR ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission file number 1-13179 FLOWSERVE CORPORATION (Exact name of registrant as specified in its charter) New York (State or other jurisdiction of incorporation or organization) 31-0267900 (I.R.S. Employer Identification No.) 75039 (Zip Code) Texas Irving, 5215 N. O'Connor Boulevard Suite 2300, (Address of principal executive offices) (972) 443-6500 (Registrant’s telephone number, including area code) Securities registered pursuant to Section 12(b) of the Act: Title of Each Class Name of Each Exchange on Which Registered New York Stock Exchange New York Stock Exchange Trading Symbol FLS FLS22A Common Stock, $1.25 Par Value 1.25% Senior Notes due 2022 Securities registered pursuant to Section 12(g) of the Act: None Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☑ No ☐ Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐ No ☑ Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☑ No ☐ Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☑ No ☐ Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer”, “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act. Large accelerated filer  ☑ Emerging growth company  ☐ Accelerated filer   ☐ Non-accelerated filer  ☐ Smaller reporting company  ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or  revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. Yes ☑ No ☐ Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☑ The aggregate market value of the common stock held by non-affiliates of the registrant, computed by reference to the closing price of the registrant’s common stock as reported on June 30, 2020 (the last business day of the registrant’s most recently completed second fiscal quarter), was approximately $3,069,855,077. For purposes of the foregoing calculation only, all directors, executive officers and known 5% beneficial owners have been deemed affiliates. DOCUMENTS INCORPORATED BY REFERENCE Certain information contained in the definitive proxy statement for the registrant’s 2021 Annual Meeting of Shareholders scheduled to be held on May 20, 2021 is incorporated by reference into Part III hereof. Number of the registrant’s common shares outstanding as of Fe bruary 17, 2021 was  130,276,070 .