An introduction to Pipe & Tube Classification

Pipe classification:

Iron pipe size (approximate internal dia.)

Manufacturers’ weight: NPS +

• STD
• XS
• XXS

Schedule number: NPS +

• 5, 5s, 10, 10s, 20, 20s, 30, 40, 40s, 60, 80, 80s, 100, 120, 140, 160
• SCH ≈ 1000 P/S
• NPS ≤ 12, OD ≥ NPS
• NPS ≥ 14, OD = NPS
• NPS ≤ 10, SCH 40 = STD
• NPS ≤ 8, SCH 80 = XS
• Light wall = light gage = 5, 5s, 10, 10s

API designation

• A25, A, B, X42, X46, X52, X60, X65, X70
• X(AA), AA = Allowable stress

Pressure-Temperature Ratings

• 150, 300, 400, 600, 900, 1500, 2500

Pipe:

• NPS:

1/8”, ¼”, 3/8”, ½”, ¾”, 1”, 1 ½”, 2”, 3”, 4”, 6”, 8”, 10”,

12”, 14”, 16”, 18”, 20”, 24”, 28”, 30”, 32”, 36”, 40”,

44”, 48” 52”, 56”, 60”

• NPS

1 ¼”, 2 ½”, 3 ½”, 5” not used

Pipe is supplied in 

• Random length (17 to 25 ft)
• Double random length (38 to 48 ft)

Pipe end:

• BE (bevel end)
• PE (plain end)
• T& C (treaded and coupled, rating of coupling shall be specified

Tube:

Specify by two of

• Outside diameter
• Inside diameter

1. Thousandths of inch
2. Gauge number

• American wire gauge
• Steel wire gauge
• Birmingham wire gauge

When gauge numbers are given without reference to a system (BWG) is implied.