INGENIEUR
Methodologies for Petronas
Sabah-Sarawak Gas
Pipeline Commissioning
By Ir. Akbal Abu, Principal Commissioning Engineer,
Group Project Delivery, PETRONAS
P
ETRONAS has successfully commissioned a
36”x 513 km Sabah-Sarawak Gas Pipeline
(SSGP) to transport dry gas from the Sabah
Onshore Gas Terminal (SOGT) in Kimanis, Sabah
to Malaysia LNG Sdn Bhd (MLNG II & MLNG
III) in Bintulu, Sarawak as well as to domestic
customers; the Sabah Ammonia & Urea Plant
(SAMUR) and PETRONAS Methanol Labuan (PML).
The feed gas comes from the offshore Kinabalu
and Kebabangan fields in Sabah and is processed
in SOGT prior to distribution.
The SSGP pipeline is designed at 96 Barg
to transport up to 750 MMscf/d of dry gas with
compression to meet the gas delivery requirement
of each customer.
The initial commissioning of the SSGP pipeline
took place in early 2014 and continued until
2016 for partial and entire re-commissioning
of the pipeline after a fire explosion incident in
June 2014. The most challenging aspect of the
commissioning was the massive co-ordination
amongst the stakeholders involved as gas network
commissioning needs to be done in an integrated
manner.
In complying with the stakeholders’
expectations, various pipeline commissioning
options were considered and adopted to suit
available resources, schedules, and most
importantly to meet safety and customer
specifications stipulated in the Gas Sales
Agreement (GSA). This article is mainly focused
on the purging aspects of pipeline commissioning
to ensure safe introduction and export of dry gas
to the customers and avoid creating a flammable
mixture of natural gas with the air left post pre-
commissioning activities such as hydrotesting,
dewatering, cleaning and drying. The presence
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of residual water in lines can have very serious
consequences, both in terms of the potential for
corrosion, and the possibility that hydrates may
form if water is present as the line is brought up
to pressure.
HYDROCARBON GAS PIPELINE
COMMISSIONING
Three methodologies were considered for the Gas-
In pipeline:
Method 1 - Natural gas injection under
pipelines vacuum conditions
without the use of pigs;
Method 2 - Natural gas injection as
propellant of a pig train
confining a nitrogen batch;
Method 3 - Natural gas injection under
pipelines pressure conditions
without the use of pigs
Method 3.1 - Inert purge by
complete filling with inert gas,
Method 3.2 - Inert purge using
an inert slug to separate natural
gas and air.
Before choosing the pipeline commissioning
method, it was essential to identify the following
factors and parameters:
● ●
Environmental and safety conditions;
● ●
Pipeline characteristics (length, diameter,
coating, geographical zone, trenching,
subsea);
● ●
Operating requirements, such as power
and space availability and existence of an
available venting system;
● ●
Cost and time limits;