Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

TurkStream Technological Advancements
Erich Jurdik

Oleg Aksyutin

South Stream Transport BV
Amsterdam, The Netherlands

South Stream Transport BV
Amsterdam, The Netherlands

Bjørn-Andreas Hugaas

Ping LiuDNV AS
Høvik, Norway

Intecsea BV
The Hague, The Netherlands

ABSTRACTThe TurkStream Offshore Pipeline is one of the last decade’s mostchallenging projects in the offshore oil and gas industry. It is a major
gas-transmission system that is pivotal to the transport of natural gas
from the large Siberian reservoirs to the Turkish and European markets.
The system consists of two subsea pipeline strings of more than 900 km
each that cross the Black Sea through water depths of up to 2,200 m. Its
large outer diameter of 32 inches makes it possible to transport amassive amount of 31.5 bcm natural gas per year from the Russian tothe Turkish shore. A very thick wall of 39 mm is needed to ensure
structural integrity.
The sheer size of the system and the conditions it will be operating inhave come with many challenges. Several are discussed in this paper.
Available technologies had to be advanced to the next level on manyfronts to realise this project.

Fig. 1: Routing of the TurkStream pipelines
This project has been a challenge on many frontiers, includingcommercial, political, regulatory, logistic and technical complexities.
However, this paper focuses merely on the technical issues. The
combination of ultra-deep water and a large diameter has resulted in theneed for a heavy wall; one that is at the limit of what present-day tierone pipe mills can manufacture in large quantities. Dedicated testing
programmes were launched, and project-specific manufacturing
requirements have been developed to ensure that the line pipe is fit toresist the tremendous external pressure acting in ultra-deep water.

The work reported in this paper was carried out between 2010 and 2019.
KEYWORDS: TurkStream; Technological Advancements; Very thickwall; Ultra-deep water; Gas Transmission; Record-setting; Pipeline.

INTRODUCTION
The TurkStream Offshore Pipeline is a major gas-transmission systemthat is currently in operation and comprises two pipeline strings in up to2200 m water depth. It connects large gas reservoirs in Russia to theTurkish gas-transportation network via the Black Sea, as shown inFig. 1. The system currently has an annual capacity to transport
31.5 bcm of natural gas over approximately 940 km. The line pipe islongitudinally welded with a nominal outer diameter (𝐷) of 813.0 mm(i.e., 32 inches) and wall thickness (𝑡) of 39.0 mm. The material gradeis DNV SAWL 450 with supplementary requirements F, D, U and(light) S as per DNV-OS-F101 (2010) plus project specifications.

It is not economical nor practicable to design the pipeline to resist
buckle propagation in the route portions with the deepest water.
Consequently, buckle arrestors (BAs) are needed to halt a propagating
buckle and to limit the maximum length of pipe lost during such an
event. These are in-line sections of very thick pipe. The installation has
been conducted using the S-lay method. This means that the BAs needto travel over a long stinger on which they are cyclically loaded due tothe individual rollers. Manufacturing and installation of the BAs havecome with their own challenges.

The line pipe is externally coated using a three-layer polypropylene(3LPP) anti-corrosion coating. A liquid-epoxy flow coating has been
applied on the inside to reduce the frictional pressure loss during
operation, and more importantly, ease pre-commissioning andcommissioning. Concrete weight coating is applied merely in shallow
water to ensure on-bottom stability.

The routes selected for the two pipeline strings cross steep slopes andareas in which geohazards threaten the system. The robustness of theon-bottom design of the pipeline on the steep slopes has been a specificpoint of attention. TurkStream is the first major pipeline that has been
pre-commissioned without a full system pressure test (SPT). This has
many benefits, yet additional measures had to be taken to ensuresufficient cleanliness and reliability.

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