Saturation: The degree of magnetization
where a further increase in magnetic field strength produces a decrease in permeability
of a material.
Scabs: See slivers.
SCC: Stress-corrosion
cracking. Environmentally assisted cracking that can result when the combined
action of stress, an electrochemical cracking environment, and temperature causes
cracks to initiate and grow in a susceptible line-pipe steel.
Seam Weld: The longitudinal
weld in pipe, which is made in the pipe mill.
Seam Weld Cracks: Cracks
in the weld or weld zone of the longitudinal seam weld of the pipe.
Selective Corrosion Cracks:
A localized corrosion attack along the bond line of electric resistance
welds (ERW) and flash welds (FW), that leads to the development of a wedge shaped
groove that is often filled with corrosion products.
Selective Pipe Replacements:
Pipe replacements undertaken adjacent to critical areas such as dwellings.
Sensors: Devices that receive
a response to a stimulus, e.g., an ultrasonic sensor detects ultrasound.
Sessile: Bacterial corrosion
due to colonies formed on the surface. (See also Planktonic)
Shear wave analysis: see
Ultrasonic thickness
Shielded Corrosion: Corrosion
between the pipe and the protective coating, which is not controlled by cathodic
protection currents. Commonly referred to as "cathodic shielding."
Side (Slip) Stream: A
bypass loop or a direct outlet from the process stream. (Fluid may or may not
be at the same velocity, temperature, and pressure as the main process stream).
Sizing: See characterization.
Slivers: A thin elongated
anomaly caused when a piece of metal is rolled into the surface of the pipe.
A sliver is usually metallurgically attached at only one end. In MFL inspections,
a sliver is sometimes called a lamination.
Slug: Confined liquids
within a gas pipeline. Smart Pig. See In-Line Inspection Tool.
Smart Pig: See In-Line
Inspection Tool.
Sour Gas: Natural gas
containing hydrogen sulfide in such proportion as to require treating in order
to meet domestic sales gas specifications.
Sparger: Perforated pipe
through which steam, air or water is sprayed.
Specified Minimum Yield Strength
(SMYS): A required strength level that the measured yield strength
of a pipe material must exceed, and which is a function of pipe grade. The measured
yield strength is the tensile stress required to produce a total elongation
of 0.5% of a gauge length as determined by an extensometer during a tensile
test.
Sphere Pig: A spherical
utility pig made of rubber or urethane. The sphere may be solid or hollow, filled
with air or liquid. The most common use of sphere pigs is as a batching pig.
Stern-Geary constant:
A polarisation resistance constant (B) used in determining a correction to the
Tafel slope in conditions within 30 mV of the corrosion potential.
Strain: Increase in length
of a material expressed on a unit length basis (e.g., inches per inch).
Strain Hardening: An increase
in hardness and strength caused by plastic deformation at a temperature below
the re-crystallization range.
Stress: Tensile or compressive
force per unit area in the pipe wall as a result of the loads applied to the
structure.
Stress corrosion cracking (SCC):
Corrosion cracking produced synergistically by the combined influence of
tensile stress and a corrosive environment. Synergistical
Stress Intensity Factor:
A fracture mechanics term relating the crack size, geometry, and stress
acting on a crack.
Stress Raiser or Concentration:
A change in contour, discontinuity, gouge, or notch that causes local increases
in the stress in a pipe.
Stress Relief:
