Pipe Diameter and Wall Thickness
NPS means “nominal pipe size”, which is the internal flow capacity of the pipe (pipe bore capacity). The comparable European term for “NPS” is “DN”. The term “NPS” replaced the previously used “Iron Pipe Size” (IPS) system, which was similarly used to designate the sizes of steel pipes.
WT means “wall thickness”, i.e. the thickness of the pipe wall expressed in inches or mm. The higher the thickness of a pipe at a given NPS, the stronger the resistance of the pipe to the pressure of the fluid and its possible corrosion. The pipe thickness is called also “pipe schedule” (abbreviated, “SCH.”). For a given NPS and schedule, the thickness of the pipe is fixed and defined in the applicable ASME standard B36.10 and ASME B36.19.
Pipe Length
1. “SRL” (“single random length”): means that the pipe has any random size between 5-7 meters; generally, pipes below 2 inches in diameter are manufactured with SRL, i.e. shorter (or half measures) of larger bore pipes
2. “DRL” (double random length): meaning that the pipe has any random size between 11-13 meters. Pipes above 2 inches in diameter are available in DRL size
3. Cut Lengths(pipe spools): pipes are cut according to project specifications. Custom sizes are used to save welding costs at the installation site.
Pipe End Types
1. Plain ends (PE): plain ends are generally used for smaller diameters and require slip-on flanges and socket weld fittings. Plain ends are also common for stainless steel pipe, duplex stainless steel pipe and nickel-alloy pipes.
2. Beveled ends (BE): this is the most common pipe end type (beveled end pipes are joined by welding).
3. Threaded ends (TE): threaded ends (which are generally NPT as per ASME B1.20.1 for petrochemical pipes) require threaded fittings and flanges and are used for smaller size pipelines or gas lines
