API 5DP is the specification for drill pipe — the tubular string that carries the bit and transmits torque and hydraulic power down the hole. It sits alongside API 5CT (casing and tubing) and API 7-1 (rotary drilling equipment), and it is the document a drill pipe order is written against.
What the specification covers
- Grades — E-75, X-95, G-105 and S-135, designated by minimum yield strength in ksi.
- Product forms — seamless and welded drill pipe with tool joints attached.
- Mechanical requirements — tensile, yield, elongation and hardness limits by grade and wall thickness.
- Upset configurations — internal upset (IU), external upset (EU) and the integrity requirements that go with each.
- Inspection — dimensional, visual and non-destructive testing requirements before the pipe leaves the mill.
What to put on the order
The grade alone is not enough. A drill pipe purchase also has to state the outside diameter, the wall thickness or weight per foot, the tool joint connection, the upset type and the inspection class. Two strings ordered to the same grade at different wall thicknesses are not interchangeable.
Download the standard
API 5DP (2009) — Specification for Drill Pipe (PDF)
Related reading
- Standards library — API, ASTM and EN specifications in one index.
- API 5CT — the casing and tubing specification that sits above the drill string.
- API 5CRA — corrosion resistant alloy tubulars for sour service.
- BS EN ISO 15156-3 — when the well contains H2S.
