Drill2Water, LLC
Water Well Drilling Rigs - Drill Pipe Size
Water Well Drilling Rigs - Drill Pipe Size
2-7/8" IF or FEDP drill pipe versus 2-3/8" Mayhew Jr drill pipe:
note: When referring to drill pipe it is customary to refer to the size pipe with the type tool joint used. Example: 2-3/8"
Mayhew Jr is 2-3/8" od pipe with Mayhew Jr tool joints. Tool joints are the ends of the pipe that screw together often
referred to as the pin and box. 2-7/8" is 2-7/8 od pipe with either IF or FEDP tool joints.
Drill pipe size makes a significant difference:
1) Larger inside diameter drill pipe provides less friction to water, mud, or air flow.
2) Less friction equates to more flow reaching the drill bit at higher pressures.
3) The larger outside diameter of the drill pipe means less room between the drill pipe and outer bore wall.
4) Less room between the drill pipe outer wall and borehole wall increases up hole velocity and flow.
5) Increased flow and velocity allows the mud pump to use less horsepower.
6) More flow due to reduced friction saves money in fuel by using less horsepower.
7) Larger diameter pipe is stiffer foot per foot.
8) Faster drilling due to increased cuttings removal.
9) Pumps last longer due to the range of rotational speeds to move fluid at higher pressures.
10) Rig drill depth and bore hole size capability is increased with more flow and pressure available.
11) Less hydraulic demand for hydraulic powered variable speed mud pumps.
2-7/8" schedule 80 drill pipe is +/- 2-3/8" id ("inside diameter") pipe. The flow through the 2-3/8" id of the pipe is
restricted by the tool joints used to connect each stick of pipe. The tool joint flow passage for 2-7/8" drill pipe is
2" (see note 2 below). On the other hand 2-3/8" Mayhew Jr is +/- 2" id pipe with a 2-3/8" od ("outside diameter").
The Mayhew Jr tool joint has a +/- 1-7/16" flow passage. The increased flow through a 2" tool joint versus 1-7/16"
tool joint is over 40%. A 40% plus increase in flow allows your drilling rig to drill faster and deeper.
Mayhew Jr pin and box are great tool joints and make a great drill pipe, however the use of 2-7/8" drill pipe with
matched tool joints allows your drilling rig perform to its design limit faster and more efficient than Mayhew Jr will
allow. If you made it this far then one other tidbit. The 2-7/8" drill pipe tool joints noted below allows greater flow
passage than 3-1/2" API Regular tool joints and just slightly less flow than 4-1/2" API Regular tool joints.
To use heavier and larger diameter drill pipe it takes power with exceptional structural strength and pipe pullback
ability. With a 12" I-beam carrier platform and a planetary torque hub Model Water-84 can pull out over 600 feet
of drill pipe using less than 62% of the rigs maximum pullback torque rating and a fraction of the maximum dual
strand chain break rating. At approximately 95 lbs per 10 ft stick 2-7/8" drill pipe can be placed by hand or by
using the high speed hydraulic powered mast tower extension winch.
note: When referring to drill pipe it is customary to refer to the size pipe with the type tool joint used. Example: 2-3/8"
Mayhew Jr is 2-3/8" od pipe with Mayhew Jr tool joints. Tool joints are the ends of the pipe that screw together often
referred to as the pin and box. 2-7/8" is 2-7/8 od pipe with either IF or FEDP tool joints.
Drill pipe size makes a significant difference:
1) Larger inside diameter drill pipe provides less friction to water, mud, or air flow.
2) Less friction equates to more flow reaching the drill bit at higher pressures.
3) The larger outside diameter of the drill pipe means less room between the drill pipe and outer bore wall.
4) Less room between the drill pipe outer wall and borehole wall increases up hole velocity and flow.
5) Increased flow and velocity allows the mud pump to use less horsepower.
6) More flow due to reduced friction saves money in fuel by using less horsepower.
7) Larger diameter pipe is stiffer foot per foot.
8) Faster drilling due to increased cuttings removal.
9) Pumps last longer due to the range of rotational speeds to move fluid at higher pressures.
10) Rig drill depth and bore hole size capability is increased with more flow and pressure available.
11) Less hydraulic demand for hydraulic powered variable speed mud pumps.
2-7/8" schedule 80 drill pipe is +/- 2-3/8" id ("inside diameter") pipe. The flow through the 2-3/8" id of the pipe is
restricted by the tool joints used to connect each stick of pipe. The tool joint flow passage for 2-7/8" drill pipe is
2" (see note 2 below). On the other hand 2-3/8" Mayhew Jr is +/- 2" id pipe with a 2-3/8" od ("outside diameter").
The Mayhew Jr tool joint has a +/- 1-7/16" flow passage. The increased flow through a 2" tool joint versus 1-7/16"
tool joint is over 40%. A 40% plus increase in flow allows your drilling rig to drill faster and deeper.
Mayhew Jr pin and box are great tool joints and make a great drill pipe, however the use of 2-7/8" drill pipe with
matched tool joints allows your drilling rig perform to its design limit faster and more efficient than Mayhew Jr will
allow. If you made it this far then one other tidbit. The 2-7/8" drill pipe tool joints noted below allows greater flow
passage than 3-1/2" API Regular tool joints and just slightly less flow than 4-1/2" API Regular tool joints.
To use heavier and larger diameter drill pipe it takes power with exceptional structural strength and pipe pullback
ability. With a 12" I-beam carrier platform and a planetary torque hub Model Water-84 can pull out over 600 feet
of drill pipe using less than 62% of the rigs maximum pullback torque rating and a fraction of the maximum dual
strand chain break rating. At approximately 95 lbs per 10 ft stick 2-7/8" drill pipe can be placed by hand or by
using the high speed hydraulic powered mast tower extension winch.
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2-7/8" IF tool joint od = 4-1/2"
2-7/8" FEDP tool joint od = 3-3/4"
2-3/8" Mayhew tool joint od = 3"
It is worth taking a moment to imagine an open bore hole with the drill pipe in it. Now imagine the larger the outside
diameter of the drill pipe the smaller the space between the drill pipe and borehole wall is. The greater the
borehole diameter the larger od of the drill pipe is preferred to close the gap between the drill pipe outer wall and
borehole wall in order to increase flow to remove cuttings. Larger boreholes require significantly more flow than
smaller boreholes. Larger id drill pipe reduces plugged drill bits due to the volume or fluid weight inside the drill
pipe being greater then the volume and weight of the fluid between the drill pipe outer wall and borehole wall. Use
of a float sub will decrease plugged bits even more.
When using high cfm / high pressure air compressors pipe tool joint id size is not nearly important as when drilling
with fluids. High pressure air easily overcomes pipe joint size restrictions with very little loss of air flow or
pressure even at depths over 500 feet .
If your drilling depths with mud are shallow the 2-3/8" Mayhew Jr drill pipe will work just fine and save you money
on your drilling rig purchase. For the larger and deeper bores requiring drilling mud the 2-7/8" drill pipe with its
much larger tool joint flow passage will significantly outperform 2-3/8" Mayhew Jr drill pipe.
diameter of the drill pipe the smaller the space between the drill pipe and borehole wall is. The greater the
borehole diameter the larger od of the drill pipe is preferred to close the gap between the drill pipe outer wall and
borehole wall in order to increase flow to remove cuttings. Larger boreholes require significantly more flow than
smaller boreholes. Larger id drill pipe reduces plugged drill bits due to the volume or fluid weight inside the drill
pipe being greater then the volume and weight of the fluid between the drill pipe outer wall and borehole wall. Use
of a float sub will decrease plugged bits even more.
When using high cfm / high pressure air compressors pipe tool joint id size is not nearly important as when drilling
with fluids. High pressure air easily overcomes pipe joint size restrictions with very little loss of air flow or
pressure even at depths over 500 feet .
If your drilling depths with mud are shallow the 2-3/8" Mayhew Jr drill pipe will work just fine and save you money
on your drilling rig purchase. For the larger and deeper bores requiring drilling mud the 2-7/8" drill pipe with its
much larger tool joint flow passage will significantly outperform 2-3/8" Mayhew Jr drill pipe.