Pipeline thermal insulation is a prevention due to temperature
difference between pipeline outer surface and inner part of the pipeline.
Pipeline thermal insulation is considered as important since its contribution
to corrosion
as well as wax and hydrate problems in offshore pipeline
system.
Pipeline insulation as figured below:
Typical Thermal Insulation on Pipeline
Source : https://anakkelautan.files.wordpress.com/2014/02/54.gif
1. Condensation That Lead to Corrosion
Pipes operating at relatively low temperature (with hot fluid flows inside, e.g. offshore pipeline) increases the potential for existing water vapour to condense on pipe surface. And this moisture may lead to corrosion on the pipeline surface.
2. Wax and Hydrate Formation
In oil and gas industry, excessive cooling of the product during transportation can result in drop out of high molecular weight waxes and asphalt. This happens due to the working temperature of the pipeline (deep in the depth, above the seabed where the temperature is relatively low). In wet gas systems, hydrate formation can block pipelines (flow).
Insulation Methods
There are few methods that can be used for insulation, such
as use
of cooling spool, material selection, and pipe in
pipe (PIP).
Use of Cooling Spools
There can be significant cost benefit from cooling the product
stream from very high temperature wells to minimize the thermal expansion
forces and then maintaining this lower temperature for through efficient
pipeline insulation reducing the volume of post lay rock dump or trenching
required or enabling more conventional materials and analysis techniques
to be employed.
Material Selection
Typically, pipeline insulation must be able to withstand the
stresses imposed as a result of the installation methods and strong enough to
withstand constant external pressure and function effectively when
submerged and saturated.
The dry, load-free environment within the annulus of the pipe
allows non-typical insulation materials with much lower thermal
conductivity to be applied subsea than has historically been possible
e.g. rock-wool systems etc. There are also few materials used for
insulation have been around for a few decades and include polypropylene,
polyurethanes, epoxies and rubbers.
Material Coating for Pipeline Thermal Insulation
Source : http://g01.s.alicdn.com/kf/HTB1zi7nGFXXXXafaXXXq6xXFXXXS/222136681/HTB1zi7nGFXXXXafaXXXq6xXFXXXS.jpg
Pipe in Pipe (PIP)
Pipe in Pipe (PIP) is installation of a second pipeline around the
product pipeline from the seawater surrounding it and creates a dry
chamber around the pipeline that can be engineered to accommodate a range
of advanced insulation techniques.
Pipe in Pipe
Source : http://terate.invista.com/~/media/INVISTA/Intermediates/TERATE/Image%20Banner/pipe-in-pipe%20jpg.ashx
Bibliography:
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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