Page 397 - Pipeline Risk Management Manual Ideas, Techniques, and Resources

372 Sample Pipeline Risk Assessment Algorithms

Variable Interpretation cont’d
pipe-maxpress, ([pipe-barlow]’(IIf( [yr]<72,(1lf([pipe_seam]= I, The pressure calculation per Barlow’s formula is
(IIf( [integrity-test]<5,0.8,0.95)),0.95)),0.95))) adjusted if low-frequency ERW pipe is present
(pre- 1970 and ERW seam type) and further
adjusted by the score for the most recent
integrity test (pressure test or in-line
inspection).
internal-con; (([prod-corr]+IIf( [drain]=l,O,5))’(lIf([yr]~94,0.5, I))) A product corrosivity score added to a “low
spot” score (ifthere is a low spot, as identified
by the [drain] variable, then 0 pts are assigned)
multiplied by an age factor, where a segment
older than 1994 receives a 50% penalty.
Sample Third-party Damage Algorithm 2
external force [pipe geometry] x [material factor] x [depth cover] x Multiply all variables together to anive at score
[exposure] x [damage prevention] for ‘external force’; variables are defined
below. Higher numbers reflect higher risk
level (Ref[48]).
pipe geometry 1 /[pipe wall1~2 + 12 / [pipe diameter] Both in inches.
material factor 1OOOOO/[pipeSMYS]+(10/[pipeCharpyVnotch])t SMYS is specified minimum yield strength in
[temp vs transition temp] psi; [Charpy Vnotch] is the Cbarpy V-notch
upper shelf energy in ft-lb, and [temp vs
transition temp] is 0 ifthe pipe is never
exposed to a temperature below its ductile-to-
brittle transition temperature, 1 if the pipe is
sometimes exposed to temperatures up to 60’F
below its transition temperature, and 10 ifthe
pipe is frequently exposed to temperatures of
60’F or more below its transition temperature
or if its transition temperature is unknown.
depth cover (3/[cover])~l.5 [cover] = depth of cover in feet
exposure 1 + 0. I x ( [foreign line xings] + [road xings] + The number of foreign line crossings, road
[river xings]) + [activity level] + 100 x [incident rate]) crossings, and river crossings in the segment;
[activity level] is a number ranging from 1 to 5
depending on the perceived construction
activity; and [incident rate] is the number of
outside force incidents per mile per year on
the segment.
damage prevention 1 + 5 x [one-call] + 5 x [patrol] + [land ownei Damage Prevention is [one-call] ranges from
communications] + [ROW] 0 to 1 and represents the one-call response,
Le., 1 for locating and marking the pipeline,
0.5 for locating, marking and providing an on-
site representative, and 0.1 if the operator
exposes the line for the excavating contractor;
[patrol] ranges from 0 to 1 and represents
patrolling, i.e., 1 .O for biweekly overflights,
0.5 for 2 overflights per week, 0.1 for 3 or
more overflights per week; [landowner
communications] ranges from 0 to 1 and
represents communication with land-owners,
i.e., 1 for none, 0.8 for periodic contacts by
mail, 0.5 for periodic face-to-face meetings;
[ROW] represents right-of-way maintenance
andmarkingandrangesfrom0.5 to l,i.e.,0.5
for robust program, 1 .O for normal program.