This standard covers the NACE SCCDA process for buried steel pipeline
systems. It is intended to
serve as a guide for applying the NACE SCCDA process on typical
petroleum (natural gas, crude oil,
and refined products) pipeline systems. Background information can be
obtained from NACE
SCCDA as described in this standard is specifically intended to
address buried onshore petroleum
(natural gas, crude oil, and refined products) pipelines constructed
from line-pipe steel.
This procedure is designed to be applied to both forms of external SCC
(near-neutral-pH SCC and
high-pH SCC) on these pipelines.
SCCDA requires the integration of data from historical records,
indirect surveys, field
examinations, and pipe surface evaluations (i.e., direct examination)
combined with the physical
characteristics and operating history of the pipeline.
This standard was written as a flexible guideline for an operator to
tailor the SCCDA process to
specific pipeline situations. Nothing in this standard is intended to
preclude modifications that
tailor the SCCDA process to specific pipeline situations and
SCCDA is a continuous improvement process. Through successive
applications, SCCDA should identify
and address locations where SCC has occurred, is occurring, or might
SCCDA provides the advantage and benefit of indicating areas where SCC
might occur in the future
rather than only areas where SCC is known to exist.
Comparing the results of successive SCCDA applications is one method
of evaluating SCCDA
effectiveness and demonstrating that confidence in the integrity of
the pipeline is continuously
SCCDA was developed as a process for improving pipeline safety. Its
primary purpose is to reduce
the threat of external SCC on pipeline integrity by means of condition
documentation, and reporting.
This standard assumes SCC is a threat to be evaluated. It can be used
to establish a baseline from
which future SCC can be assessed for pipelines on which SCC is not
currently a significant threat.
SCCDA is complementary with other inspection methods such as in-line
inspection (ILI) or
hydrostatic testing and is not necessarily an alternative or
replacement for these methods in all
instances. SCCDA also is complementary with other direct assessment
procedures such as those given
in the proposed NACE standard recommended practice on internal
corrosion direct assessment (ICDA)
ILI or hydrostatic testing might not be warranted if the initial SCCDA
assessment indicates that
"significant" and extensive cracking is not present on a pipeline
SCCDA can be used to prioritize a pipeline system for ILI or
hydrostatic testing if significant and
extensive SCC is found.
SCCDA may detect other pipeline integrity threats, such as mechanical
damage, external corrosion,
etc. When such threats are detected, additional assessments and/or
inspections shall be performed.
The pipeline operator shall utilize appropriate methods such as ASME
B31.8S, ASME B31.4, ASME
B31.8, API(Footnote 2) 1160, NACE standards, international standards,
and other documents to
address risks other than external SCC.
SCCDA can be applied to most onshore petroleum pipelines, regardless
of the coating system.
Precautions should be taken when applying these techniques just as
with other assessment methods.
Given the diversity of pipelines and their operation, this standard
recognizes that SCCDA may be
inappropriate for some situations because of the complexity of
conditions to which buried pipeline
systems are exposed.
The provisions of this standard shall be applied under the direction
of competent persons who, by
reason of knowledge of the physical sciences and the principles of
engineering, geosciences, and
mathematics, acquired by education and related practical experience,
are qualified to engage in the
practice of corrosion control, integrity management, and risk
assessment on buried steel pipeline
Footnote 2 - American Petroleum Institute (API), 1220 L St. NW,
Washington, DC 20005.
Customers who purchased NACE SP0204
- API RP 1102 : Steel Pipelines Crossing Railroads and Highways-SEVENTH EDITION; Incorporating Errata: November 2008, Errata 2, May 2010
- API SPEC 5L : Specification for Line Pipe-FORTY-FOURTH EDITION; Incorporating Errata: January 2009, Addendum 1: February 2009, Addendum 2: April 2010; Addendum 3: July 2011 Effective Date: January 1, 2012; ISO 3183:2007 Adoption
- API SPEC 6D CHINESE : Specification for Pipeline Valves-Twenty-Third Edition; Incorporates Errata 1: June 2008, Errata 2: November 2008, Errata 3: February 2009; Errata 4; ISO 14313:2007 Adoption
- API STD 1104 : Welding of Pipelines and Related Facilities-Twentieth Edition; Incorporates Errata/Addendum: July 2007, Errata 2: December 2008
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