Nationalization of Venezuelan Subsidiaries

May 2009,

within the framework of Decree Law

6058,

Venezuela’s President announced the nationalization of, among other companies, the Company's majority-owned subsidiaries TAVSA - Tubos de Acero de Venezuela S.A. (“Tavsa”) and, Matesi Materiales Siderúrgicos S.A (“Matesi”), and Complejo Siderúrgico de Guayana, C.A (“Comsigua”), in which the Company has a non-controlling interest (collectively, the “Venezuelan Companies”). Tenaris and its wholly-owned subsidiary, Talta - Trading e Marketing Sociedad Unipessoal Lda (“Talta”), initiated arbitration proceedings against Venezuela before the ICSID in Washington D.C. in connection with these nationalizations.

Matesi

January 29, 2016,

the tribunal released its award on the arbitration proceeding concerning the nationalization of Matesi. The award upheld Tenaris’s and Talta’s claim that Venezuela had expropriated their investments in Matesi in violation of Venezuelan law as well as the bilateral investment treaties entered into by Venezuela with the Belgium-Luxembourg Economic Union and Portugal. The award granted compensation in the amount of

$87.3

million for the breaches and ordered Venezuela to pay an additional amount of

$85.5

million in pre-award interest, aggregating to a total award of

$172.8

million, payable in full and net of any applicable Venezuelan tax, duty or charge. The tribunal granted Venezuela a grace period of

six

months from the date of the award to make payment in full of the amount due without incurring post-award interest, and resolved that if

no,

full, payment is made by then, post-award interest will apply at the rate of

per annum. As of

December 31, 2017,

post-award interest amounted to

$31.9

million.

March 14, 2016,

Venezuela requested the rectification of the award pursuant to article

(

) of the ICSID Convention and ICSID Arbitration Rule

49.

The tribunal denied Venezuela’s request on

June 24, 2016,

ordering Venezuela to reimburse Tenaris and Talta for their costs. On

September 21, 2016,

Venezuela submitted a request for annulment of the award as well as the stay of enforcement of the award in accordance with the ICSID Convention and Arbitration Rules, and the ad hoc committee that will hear Venezuela’s request was constituted on

December 27, 2016.

March 24, 2017,

the ad hoc committee rendered its decision to lift the stay of enforcement of the award. The ad hoc committee has

not

reserved its right to reopen that decision and

appeal against such decision is provided under ICSID’s Arbitration Rules.

The parties exchanged

two

rounds of written submissions on Venezuela’s request for annulment. Following the resignation of

one

of the ad hoc committee members, the committee was reconstituted on

November 3, 2017,

and the final hearing on Venezuela’s annulment request was rescheduled for

March 22-

23,

2018.

Following the hearing, the ad hoc committee will deliberate and issue a decision on Venezuela’s annulment application. While there is

deadline by which the ad hoc committee must render its decision, it is presently expected that the ad hoc committee will render a decision between

June

and

September 2018.

Tavsa and Comsigua

December 12, 2016,

the tribunal issued its award upholding Tenaris’s and Talta’s claim that Venezuela had expropriated their investments in Tavsa and Comsigua in violation of the bilateral investment treaties entered into by Venezuela with the Belgium-Luxembourg Economic Union and Portugal. The award granted compensation in the amount of

$137

million and ordered Venezuela to reimburse Tenaris and Talta

$3.3

million in legal fees and ICSID administrative costs. In addition, Venezuela was ordered to pay interest from

April 30, 2008

until the day of effective payment at a rate equivalent to LIBOR +

per annum, which as of

December 31, 2017

amounted to

$88

million.

April 11, 2017,

Venezuela submitted a request for annulment of the award as well as the stay of enforcement of the award in accordance with the ICSID Convention and Arbitration Rules. Venezuela’s annulment request was registered on

April 14, 2017.

The ad hoc committee that will hear Venezuela’s request was constituted on

October 17, 2017.

October 19, 2017,

Tenaris and Talta filed an opposition to Venezuela’s request to continue the stay of enforcement of the award, which was followed by the exchange of additional written submissions between the parties. The ad hoc committee has extended the provisional stay of enforcement of the award until it rules on Venezuela’s request. A hearing on Venezuela’s request to continue the stay of enforcement of the award was held on

February 1, 2018,

and will be followed by a decision from the ad hoc committee. The final hearing for Venezuela’s annulment request is scheduled for

August 27-

28,

2018.

Following the hearing, the ad hoc committee will deliberate and issue a decision on Venezuela’s annulment application. While there is

deadline by which the ad hoc committee must render its decision, it is presently expected that the ad hoc committee will render a decision between

November 2018

and

February 2019.

Based on the facts and circumstances described above and following the guidance set forth by IAS

27R,

the Company ceased consolidating the results of operations and cash flows of the Venezuelan Companies as from

June 30, 2009,

and classified its investments in the Venezuelan Companies as financial assets based on the definitions contained in paragraphs

(c)(i) and

of IAS

32.

The Company classified its interests in the Venezuelan Companies as available-for-sale investments since management believes they do

not

fulfil the requirements for classification within any of the remaining categories provided by IAS

and such classification is the most appropriate accounting treatment applicable to non-voluntary dispositions of assets.

Tenaris or its subsidiaries have net receivables with the Venezuelan Companies as of

December 31, 2017,

for a total amount of approximately

$27

million.

The Company records its interest in the Venezuelan Companies at its carrying amount at

June 30, 2009,

and

not

at fair value, following the guidance set forth by paragraphs

(c),

AG80

and

AG81

of IAS

39.