The example of natural gas transmission pipelines in the
US alone (Figure 1) reveals the challenge the pipeline industry
is facing today. According to Kiefner and Rosenfeld (2012),
approximately 66% of all natural gas transmission pipelines in the
US were installed prior to 1970.
1
This translates into 200 000 miles
(320 000 km) that are likely affected by incomplete and/or
uncertain records.
The integrated approach
With a novel integrated approach, ROSEN offers a service for
pipeline property and MAOP validation at highest confidence. The
company’s integrated approach is:
)
Verifiable – confirmed by other complementary, but separate,
documentation.
)
Traceable – originating from specific sources containing all
information for MAOP calculation.
)
Complete – finalised and evidenced by signature, date or
other appropriate marking.
ROSEN’s integrated approach comprises of three
complementary activities. The combination of these activities
addresses all aspects required for the validation of the maximum
allowable operating pressure. The gathered information is prepared
for easy integration into a geographical information system (GIS)
and to be further processed in an integrity management system
(IMS). The combination of activities is adjusted to project specific
needs. This ensures an optimised process and the highest possible
efficiency.
A comprehensive review and alignment of records
(centrelines, associated data, as-built drawings, pipe-tallies
including design calculations of piping, fittings, hydrotest pressure
records, previous and current operating conditions, MAOP, etc.) is
provided. Analogue information is digitised and incorporated into
a GIS or IMS database.
The high degree of automation of the ROSEN data analysis
routines and processes, and redesigned algorithm allow for
efficient, in-depth analyses, of existing ILI data obtained from
previous inspection runs with regards to pipeline properties,
which at the same time are used to validate and update route
information coming from a pipeline GIS.
Challenges of MAOP validation
Conventional ILI technologies are capable of delivering relevant
information for MAOP calculation, such as wall thickness and
diameter. However, as a missing element, in the past there
has been no economic means for accurately measuring yield
strength. When pipe yield strength data is missing, operators are
required, by regulation, to either base the MAOP calculation on
conservative assumptions of yield strength or remove the pipe
from service for destructive tensile testing. Aware of the existing
market need, ROSEN has developed the first ILI system capable of
continuously identifying and differentiating the pipe steel grade
and its subsequent yield strength.
ROSEN’s innovative material characterisation services RoMat
assists the operator and provides an assessment of the pipe
property yield strength of each pipeline joint.
In comparison to other statistics analysed by ‘in the ditch’
methods, ROSEN’s innovative RoMat service delivers a high
resolution strength profile of the entire examined pipeline section.
There is no longer a need for critical assessments because the pipe
properties of every joint are known. The pipe grade assessment
concludes with a report of the specified minimum yield strength
(SMYS) according to the ASME B 31.8 and the API 5L.
This makes ROSEN’s technology for RoMat ILI services first
choice for regulatory requirements to guarantee safe service
conditions.
The key advantages are:
)
Rebuilding of pipe property SMYS for entire pipeline sections.
)
Completion of known SMYS gaps in pipe tallies.
Figure 3.
Review and reporting of aligned records in Alignment
Sheet.
Figure 1.
Diagram showing the relative pipeline installation by
decades with a maximum in the 1960s.
Figure 2.
Schematic view of ROSEN’s integrated approach.
46
World Pipelines
/
JANUARY 2015
