Filed by: McDermott International, Inc.

pursuant to Rule 425 under the Securities Act of 1933

and deemed filed pursuant to Rule 14a-6

under the Securities Exchange Act of 1934

Subject Company: Chicago Bridge & Iron Company N.V.

Form S-4 File Number: 333-222662

We wanted to remind you that our Special Meeting of Stockholders is scheduled to occur this Wednesday – May 2, 2018. We urge all stockholders to vote for each of the proposals relating to our combination with CB&I. If any of you have questions or need assistance voting your shares please call MacKenzie Partners, the proxy solicitor assisting us with the Special Meeting, toll-free at 1-800-322-2885.

Additional Information and Where to Find It

This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any proxy, vote or approval with respect to the proposed transactions or otherwise, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. In connection with the proposed transactions, McDermott International, Inc. (“McDermott”) has filed a Registration Statement on Form S-4 (the “Registration Statement”) with the U.S. Securities and Exchange Commission (the “SEC”) that includes (1) a joint proxy statement of McDermott and Chicago Bridge & Iron Company N.V. (“CB&I”), which also constitutes a prospectus of McDermott and (2) an offering prospectus of McDermott Technology, B.V. in connection with McDermott Technology, B.V.’s offer to acquire CB&I shares. The Registration Statement was declared effective by the SEC on March 29, 2018. McDermott and CB&I have mailed the definitive joint proxy statement/prospectus to stockholders of McDermott and shareholders of CB&I. In addition, McDermott and McDermott Technology, B.V. have filed a Tender Offer Statement on Schedule TO-T (the “Schedule TO”) with the SEC and CB&I has filed a Solicitation/Recommendation Statement on Schedule 14D-9 (the “Schedule 14D-9”) with respect to the exchange offer. The solicitation and offer to purchase shares of CB&I’s common stock is only being made pursuant to the Schedule TO and related offer to purchase. This material is not a substitute for the joint proxy statement/prospectus, the Schedule TO, the Schedule 14D-9 or the Registration Statement or for any other document that McDermott or CB&I may file with the SEC and send to McDermott’s and/or CB&I’s shareholders in connection with the proposed transactions. BEFORE MAKING ANY VOTING OR INVESTMENT DECISION OR DECISION WITH RESPECT TO THE EXCHANGE OFFER, WE URGE INVESTORS OF CB&I AND MCDERMOTT TO READ THE REGISTRATION STATEMENT, JOINT PROXY STATEMENT/PROSPECTUS, SCHEDULE TO (INCLUDING THE OFFER TO PURCHASE, RELATED LETTER OF TRANSMITTAL AND OTHER OFFER DOCUMENTS) AND SCHEDULE 14D-9, AS EACH MAY BE AMENDED OR SUPPLEMENTED FROM TIME TO TIME, AND OTHER RELEVANT DOCUMENTS FILED BY MCDERMOTT AND CB&I WITH THE SEC CAREFULLY BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT MCDERMOTT, CB&I AND THE PROPOSED TRANSACTIONS.

Investors are able to obtain free copies of the Registration Statement, joint proxy statement/prospectus, Schedule TO and Schedule 14D-9, as each may be amended from time to time, and other relevant documents filed by McDermott and CB&I with the SEC at http://www.sec.gov, the SEC’s website, or free of charge from McDermott’s website (http://www.mcdermott.com) under the tab, “Investors” and under the heading “Financial Information” or by contacting McDermott’s Investor Relations Department at (281) 870-5147. These documents are also available free of charge from CB&I’s website (http://www.cbi.com) under the tab “Investors” and under the heading “SEC Filings” or by contacting CB&I’s Investor Relations Department at (832) 513-1068.

Participants in Proxy Solicitation

McDermott, CB&I and their respective directors and certain of their executive officers and employees may be deemed, under SEC rules, to be participants in the solicitation of proxies from McDermott’s and CB&I’s shareholders in connection with the proposed transactions. Information regarding the officers and directors of McDermott is included in its annual report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 21, 2018, as amended by its annual report on Form 10-K/A filed with the SEC on March 8, 2018. Information regarding the officers and directors of CB&I is included in its annual report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 21, 2018, as amended by its annual report on Form 10-K/A filed with the SEC on March 22, 2018. Additional information regarding the persons who may be deemed participants and their interests is set forth in the Registration Statement and joint proxy statement/prospectus and other materials filed with the SEC in connection with the proposed transactions. Free copies of these documents may be obtained as described in the paragraphs above.