INTRODUCTION:
Ø A pressure tight cylinder used to convey fluids under pressure through materials of
commercially available designation.
Ø Pipe is always designated through nominal bore size(NBS) also called as nominal pipe
size(NPS)
Ø A pipeline conveys a fluid from one given point of the plant usually called inlet
point of the line, to another part of the plant usually called outlet point of the line.
NOMINAL PIPE SIZE (NPS):
Pipe
size is specified with two non-dimensional numbers: a Nominal Pipe Size
(NPS) and a schedule (SCH). The relationship of these numbers to the
actual pipe dimensions is a bit strange.
The NPS is very loosely related to the inside diameter in inches, but only for NPS 1/8 to NPS 12.
For
NPS 14 and larger, the NPS is equal to the outside diameter (OD) in
inches. For a given NPS, the OD stays constant and the wall thickness
increases with larger SCH. For a given SCH, the OD increases with
increasing NPS while the wall thickness increases or stays constant.
NOMINAL DIAMETER (DN):
It is same as nominal pipe size, but in mm.
SCHEDULE (WALL THICKNESS):
Schedule:
Carbon steel : 5, 10, 20, 30, 40, 60, 80, 100, 120, 160.
Stainless steel : 5S, 10S, 20S, 30S, 40S, 60S, 80S.
Weight series:
Wall
thickness is designated by schedule number or descriptive
classification, rather than the actual wall thickness. The original
thicknesses were referred to as standard (STD), extra strong (XS) and
double extra strong (XXS).
Wall
thickness for the schedule 40 and STD are same for sizes ⅛ to
10”.schedule 80 and XS also have the same wall thickness for ⅛ to 8”
diameter pipe.
CODES:
Ø ASME B36.10 - CARBON STEEL
Ø ASME B36.19 - STAINLESS STEEL
MATERIAL:
Carbon steel:
Steel is basically a solution of carbon (C) into iron (Fe). The presences of
carbon
into the crystal structure of the iron improve very much the mechanical
characteristics of the iron alone. Carbon steel is a conventional
denomination for steel that has almost no other metallic elements added
into it.
Carbon steel material specification ASTM A106 is available in grades A, B
and C. These refer to the tensile strength of the steel, with grade C having the highest strength.
Common practice is to manufacture the pipe as A106 grade B
ASTM A53 is also commonly specified for galvanized or lined pipe or as an
alternate
to A106.the testing requirement for A53 are less stringent(rigorous or
tight) than for A106. Three types of carbon steel pipe are covered by
A53. These are type E or Electric resistance welded, type F or
Furnace-butt welded, and type S or Seamless. Type E and S are available
in grade A and B, comparable to grades A and B of A106.
Stainless steel:
Austenitic stainless steel pipe commonly referred to as “Stainless Steel” is
virtually non-magnetic. Stainless steel is manufactured in accordance with
ASTM A312 when 8” or smaller sizes are needed. There are eighteen different grades, of which type 304L is the most widely used.
Grade 316L has high resistance to chemical and salt water corrosion and is
best suited for welding. Large sizes (8” and up) of stainless steel pipe are covered by ASTM A358. Extra light wall thickness (schedule 5S) and light wall thickness (schedule 10S) stainless steel pipe is covered byASTM A409.
PIPE MANUFACTURING METHOD:
Ø Seamless
Hot rolled, cold drawn etc
Ø Electric resistance welding
No material is added during welding process
Ø Electric fusion welding
Filler material is added during welding process
CHARACTERISTICS OF A PIPELINE:
Ø Nominal pipe size(NPS)
Ø Wall thickness
Ø Type of joint between pieces
Welded joints
Ø Butt welded
Ø Socket welded
Threaded joints
Flanged joints
Ø External finishing
Painting
Insulation
OTHER CHARACTERISTICS OF A PIPELINE:
Routing:
Ø The routing is how the Pipeline is developed into the space.
Ø There are rules and regulations to route a Pipeline according the
“Good Engineering Practice”
Ø Cold Pipelines connecting static objects (something that does not move
like Tanks, Vessels, other Pipelines, and Headers) can be straightly
routed between the inlet and the outlet point.
Ø Cold Pipelines connecting machines that vibrate or rotate may need a
flexible part between the inlet and the outlet point.
Ø Hot Pipelines must be flexible enough to adsorb the thermal expansion
of the Pipeline from cold to hot condition
Supporting System:
Ø Every Pipeline must be supported. Not all Pipelines are supported in
the same way.
Ø Cold Pipelines can be supported everywhere with fixed points
Ø Hot Pipelines cannot be supported only with fixed points, but certain
points must be only guided, meaning that in those points the Pipeline
retains a certain numbers of degree of freedom in certain directions,
while are constrained in certain other directions.
TYPE OF JOINT BETWEEN PIECES:
1. Butt welded joint:
The end is machined to allow head to head full penetrating welding
2. Socket welded joint:
A socket is provided where pipe can be inserted
3. Threaded joint:
Parts to be connected are threaded.
PIPE ENDS:
Pipe may be obtained with
Ø Plain ends are cut square and reamed to remove burns. This
type of end is needed when being joined by mechanical couplings, socket weld fittings, or slip-on flange.
Ø Bevelled ends are required for most butt weld application.
Ø Threaded ends are used with screwed joints and are ordered
noting threaded on both ends or one end.
Various combination of pipe end:
-
POE: Plain one end
-
PBE: Plain both end
-
BOE: Bevelled one end
-
BBE: Bevelled both end
-
TOE: Threaded one end
-
TBE: Threaded both end
PIPE REPRESENTATION:
Up to 12 inch
Above 14 inch
SPECIFICATION OF A PIPE:
Example:
Size : NPS 12”
Diameter : DN 300
Wall thickness: Sch. 40
Material : ASTM A106 Gr. B
