A comprehensive description of steel pipe size and dimensions includes the outer diameter (OD), wall thickness (WT), and pipe length (usually 20 ft/6 meters or 40 ft/12 meters).
These characteristics allow for the calculation of pipe weight, pressure-bearing capacity, and cost per foot or meter. Therefore, knowing the correct pipe size is crucial.
Sizes & Dimension Standards for Steel Pipe:
There are different standards for describing steel pipe size, OD, and wall thickness, mainly ASME B 36.10 and ASME B 36.19.
Relevant Standard Specifications:
ASME B 36.10M and B 36.19M are standard specifications for the dimensions of steel pipes and accessories.
ASME B36.10M:
Covers the standardization of steel pipe dimensions and sizes, including seamless or welded types, for high or low temperature and pressures.
Distinguishes pipes from tubes, specifically for pipeline systems and fluid transmissions.
ASME B36.19M:
Another standard specification covering steel pipe dimensions and sizes.
Steel Pipe Sizes & Dimensions Schedule:
Steel pipe schedule is indicated by ASME B 36.10 and used in many other standards, marked with "Sch."
"Sch" is the abbreviation for schedule and appears in the American steel pipe standard, serving as a prefix for a series number (e.g., Sch 80).
Nominal Pipe Size (NPS):
NPS is a North American set of standard sizes for pipes, specified with two non-dimensional numbers: a nominal pipe size based on inches and a schedule.
DN (Nominal Diameter):
Nominal diameter, also known as outside diameter, is used as the general diameter of various pipes and pipeline accessories. It is represented by a digital symbol followed by the letter "DN" and marked in millimeters.
Pipe Weight Class Schedule:
WGT class (weight class) indicates pipe wall thickness, with grades such as STD (standard), XS (extra strong), and XXS (double extra strong).
Describing Steel Pipe Dimensions and Size:
Steel pipe dimensions can be described as:
Expressed as "pipe outside diameter × wall thickness."
Expressed as "NPS x Schedule."
Expressed as "NPS x WGT Class."
In North and South America, it is often expressed as "Pipe Outer Diameter x lb/ft" (pound per feet).
Examples:
A. Φ 88.9mm x 5.49mm (3 1/2” x 0.216”), length 6m or 12m.
B. NPS 3 inch x Sch 40, NPS 4 inch x Sch 40.
C. NPS 3 inch x SCH STD, NPS 4 inch x SCH STD.
D. OD 3 1/2”, 16.8 lb/ft.
Understanding these specifications is essential for selecting the right steel pipe size for various applications.
