OISD – STD – 226 Page No.

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Sr.Number:OISD/DOC/2013/158
NATURAL GAS TRANSMISSION PIPELINES AND CITY GAS
DISTRIBUTION NETWORKS

etc. affected by tidal fluctuations, waves and currents and cannot be installed using
conventional onshore equipment could be designed in accordance with Det Norske
Veritas (DNV) Standard FS-101/ OISD-Std-139.

5.1.1 A design life of minimum 25 years for pipeline system shall be considered by the
owner for designing various system and facilities beyond which pipeline system can
be considered for abandonment. The life of pipeline can be extended beyond the
design life subject to satisfying the comprehensive pipeline integrity test.

5.1.2 All necessary calculations shall be carried out to verify structural integrity and
stability of the pipeline for the combined effect of pressure, temperature, bending,
soil/pipe interaction, external loads and other environmental parameters as
applicable, during all phases of work from installation to operation. Such calculations
shall include but not limited to the following:

(a) Buoyancy control and stability analysis for pipeline section to be installed in
areas subjected to flooding/submergence,
(b) Crossing analysis of rivers by trenchless techniques, wherever soil data is
favourable for such operation,
(c) Evaluation of potential for earthquake occurrence across fault location and
carrying out requisite seismic analysis to ensure safety and integrity of the
pipeline system.

5.1.3 A significant factor contributing to the failure of a pipeline is the damage caused to
the pipeline by activities along the route of the pipeline associated with human
dwellings and commercial/industrial installations. An appropriate Location Class
related to the number of buildings meant for human occupancy shall be determined
along entire pipeline route in accordance with Annexure-II. Pipelines and its
associated facilities shall be designed selecting appropriate design factor as per para
5.2.1

5.1.4 Design temperature

Maximum temperature
Maximum temperature for design of above ground section of pipeline / piping shall be
maximum expected gas temperature during operation or maximum ambient
temperature whichever is higher.

Maximum temperature for design of buried section of pipeline / piping shall be

Minimum temperature
Minimum temperature for design shall be minimum expected gas temperature during
operation or minimum ambient / sub-soil temperature whichever is lower. In no case
minimum temperature for carbon steel pipelines be less than (-) 29oC.

“OISD hereby expressly disclaims any liability or responsibility for loss or damage resulting
from the use of OISD Standards/Guidelines.”
 Sr.Number:OISD/DOC/2013/158

OISD – STD – 226 Page No. 23

8.2.2 Mill Hydrotest

Line pipes are recommended to be hydrostatically tested in pipe mill using test pressure
that produces a hoop stress equal to 95% of SMYS irrespective of grade of pipe material.
The pressure shall be held for a minimum period of 15 seconds.

8.2.3 Fracture Toughness

Carbon steel line pipes shall meet the fracture toughness requirements stipulated in ASME
B 31.8

8.3 Notch Toughness Requirements

For carbon steel pipes and other steel components of size 2" NPS and larger, Notch
toughness values shall be determined to provide protection against fracture initiation and
propagation. Notch toughness values (minimum absorbed impact energy values) shall be
specified based on the design operating stress and the minimum design temperature.

For carbon steel pipes and other components smaller than size 2" NPS proven notch
toughness properties are not mandatory.

8.4 Requirements for Sour Gas Service

8.4.1 Gaseous hydrocarbon shall be considered as sour in line with NACE Standard MR-01-75.
At lower concentrations of H2S, as the presence of other constituents in the gas e.g., CO2
and salts in water etc., can also cause stress corrosion, hence the concentration of such
constituents shall also be evaluated in gaseous hydrocarbon.

8.4.2 All materials, used in sour gas service, shall conform to the material requirements
specified in NACE Standard MR-01-75. Depending upon service and materials involved,
additional tests for Sulphide Stress Corrosion Cracking (SSCC) and Hydrogen Induced
Cracking (HIC), as specified in NACE Standards MR-01-75 and TM-02-84 respectively,
should also be conducted for long & short term behavior of material under corrosive
environments.

9.0 CORROSION CONTROL

9.1 General

9.1.1 All above ground and buried pipelines shall be adequately protected against external
corrosion.

9.1.2 Above ground sections of pipelines shall be electrically isolated from the buried pipeline
sections. This requirement, however, need not be applied to above ground pipeline section
on suspension and / or bridge crossings.
“OISD hereby expressly disclaims any liability or responsibility for loss or damage resulting
from the use of OISD Standards/Guidelines.”