Offshore pipeline installation is the next step after
designing. These days, there are few methods that commonly used and can be
adapted to install offshore pipeline system, such as S-Lay
method, J-Lay method, O-Lay method, Reel Lay method, and Beach Pull.
S-Lay Method
This method is quiet time-saving and can be done in vary
depths. S-Lay refers to the pipeline shape forming “S” during the installation.
This method requires lay-barge or other vessel
designed to pipe-laying. Pipe is eased off the stern of the vessel as the boat
moves forward. The pipe curves downward from the stern through the water until
it reaches the seafloor. As more pipe is welded in the line and eased off the
boat, the pipe forms the shape of an “S” in the water. Stingers, measuring
up to 91 meters long, extend from the stern to support the pipe as it is moved
into the water, as well as control the curvature of the installation. Some
pipe-lay barges have adjustable stingers, which can be shortened or lengthened
according to the water depth.
In S-Lay method, pipe receive more stress, especially at the
bending (curve). This may become a concern due to pipe-cracking.
S-Lay Method Schematic
Source : https://anakkelautan.files.wordpress.com/2014/01/32.jpg
S-Lay Barge
Source : https://oilandgastechnologies.files.wordpress.com/2012/09/s-lay.png
J-Lay Method
J-Lay method put less stress on the pipe during
installation, since there are only one bend (curve) forming the shape of “J”.
This method inserts the pipeline in an almost vertical position. Pipe is lifted
by a tall tower on the boat/barge, then inserted into the sea. The pipe bends
once, under the water, taking on the shape of “J”.
J-Lay Method Schematic
Source : https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhB36sUGbmDegfkiV4TJvXAuyEAtAWEUSmQ2gwgzha2xINomMSNheNBgIcuPjCd2nPZUkCQoyhdpDLhztS9Nhe7Bw-pNxvUv6t-MzxK9YyMMpy4xH6jb9YR7t27KjVn83OyrtDexsMuZDnS/s400/3.jpg
J-Lay Barge
Source : http://www.wermac.org/nordstream/ns_images/nordstream36.jpg
O-Lay Method
By using the O-lay technology operational production costs can be reduced compared to the existing general methods of pipe laying offshore. With O-lay, the pipe laying operations will be faster than other methods used today. Pipe line installation of larger diameter pipe can be as fast as 25 km per day. Furthermore the technology is safer because there are less people working in the offshore environment and the offshore operations are done in a shorter period of time.
The bottleneck of welding and testing on the traditional lay-barge is not a procedure that is part of the installation process anymore. Welding and testing are done on an onshore construction site.
O-Lay Method Schematic
Source : http://www.o-lay.net/images/o-lay-PIJPNAAR_BODEM_lang.jpg
Reel Lay Method
This method is firstly proposed to install pipeline with
relatively small in diameter. But it have been developed to install pipeline
with 12″ to 16″ diameter in size. This method used coiled pipe on a spool
(reel) resulting in fast productivity due to the ability to lay the pipe by
“unwinding” it from the reel. The process costs due to the reduced number
of personnel required to lay the pipe, lowering the risk of accidents at the
same time, and providing efficiency in the availability of the pipe.
Each reel is designed to operate with a specific barge
and can usually handle pipe from 2″ to 12″. The total length capacity depends
on the spool dimensions and the diameter of the pipe.
Reel-Lay Method Schematic
Source : http://www.tomarine.com/images/Reel-Lay-01.png
Reel Lay Barge
Source : http://www.offshore-mag.com/content/dam/offshore/print-articles/Volume%2072/sept/bond1-1209off.jpg
Beach Pull Method
Beach pull or also known as shore pull method is adapted for
a near-shore pipe installation that is perpendicular to the shoreline, with
pulling pipeline from the shore. Pipe is welded on a lay barge where the end of
the pipe to shore set with pull head. Pull head hooks
cable from shore.
The cable is connected to a winch on shore. Pulled pipe then
glided into water through its route. Each segment of pipe is completed with
buoy. When all pipes are on they’re position, buoys then being released.
Beach Pull Schematic
Source : Slide KL4200 Subsea Pipeline
Beach Pull Method
Source : https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQW75xUwCnKfrgPykHWPxuj_kLV3dJrYjVgKnFeSfTNLBBmUCFk
References:
Santika, Anindya Rizki. Laporan tugas akhir: Desain dan
Analisis Instalasi Pipa Bawah Laut Menggunakan DNV OS F101 2010 dan DNV 1981.
Bandung. 2011.
https://nonerieska.wordpress.com/2013/01/30/offshore-pipeline-installation/
http://www.o-lay.net/
Dega Damara Aditramulyadi
Student ID : 15512046
Course : KL4220 Subsea Pipeline
Lecturer : Prof. Ir. Ricky Lukman Tawekal, MSE, Ph. D.
Eko Charnius Ilman, ST, MT
Ocean Engineering Program, Institut Teknologi Bandung
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