01 // Transition
Between Pipe and Collars
Heavy weight sits between flexible drill pipe and rigid drill collars, where the stiffness change would otherwise concentrate bending stress in a single joint.
Drill String Transition
Heavy Weight Drill Pipe
A transitional member between flexible drill pipe and rigid drill collars, dampening bending stresses where fatigue failures start. Supplied in two sizes, with either connection. We carry both, so the choice is yours.
What We Carry
Two Sizes, Either Connection
We stock heavy weight drill pipe in 4.5″ and 5.5″. Heavy weight is the pipe itself; Delta™ and CET are the rotary-shouldered connections welded to it. The assembly you receive is specified by both: size and connection together.
The figures below are published by the connection manufacturers for the complete assembly, not the tube alone. They are the numbers to plan a string against, and they differ from the drill pipe figures on the Delta and CET pages, which cover a different product. For drill pipe rather than heavy weight, the two connection families are set out side by side on the home page.
Data Sheet
Assembly Specifications
| 4.5″ Delta™ 425 | 5.5″ Delta™ 544 | 5.5″ CET54 | |
|---|---|---|---|
| Manufacturer | NOV Grant Prideco | NOV Grant Prideco | Command Tubular Products |
| Pipe body grade | Standard HW | Standard HW | Welded 70 ksi |
| Nominal OD (in) | 4.500 | 5.500 | 5.500 |
| Nominal ID (in) | 2.750 | 3.250 | 3.250 |
| Approx. length (ft) | 31.7 | 31.8 | 31.0 (Range II) |
| Adjusted weight (lb/ft) | 37.21 | 57.45 | 56.97 |
| Drift (in) | 2.500 | 3.000 | 3.125 |
| Tensile strength (lbs) | 548,100 | 850,400 | 1,082,377 |
| Torsional strength (ft-lbs) | 40,700 | 75,900 | 96,549 |
| Burst (psi) | 18,720 | 19,690 | 25,057 |
| Collapse (psi) | 17,229 | 17,897 | 22,779 |
| Section modulus (in³) | 7.698 | 14.342 | 14.342 |
| Polar section modulus (in³) | 15 | 29 | 28.685 |
| Fluid displacement (gal/ft) | 0.569 | 0.878 | 0.872 |
| Fluid capacity (gal/ft) | 0.309 | 0.431 | 0.460 |
Compare these three, but not as a like-for-like ranking. The Delta assemblies use a standard heavy weight pipe body grade and the CET assembly is welded 70 ksi, so the tube differs as well as the connection. That is why the two 5.5″ columns diverge on tensile, torsional, burst and collapse despite sharing a section modulus, and it means the CET figures are not evidence of a better connection. We carry and rent both families, so specify by application rather than by column, and confirm with us before ordering.
Tool Joints
Connection and Make-Up Torque
| Delta™ 425 | Delta™ 544 | CET54 | |
|---|---|---|---|
| Tool joint OD (in) | 5.375 | 6.625 | 6.625 |
| Tool joint ID (in) | 2.750 | 3.250 | 4.000 |
| Tool joint SMYS (psi) | 130,000 | 130,000 | 130,000 |
| Tool joint torsional strength (ft-lbs) | — | — | 80,900 |
| Recommended make-up torque (ft-lbs) | 34,100 | 52,000 | 52,600 |
| Minimum make-up torque (ft-lbs) | 24,300 | 43,300 | 44,800 |
| Extended make-up torque (ft-lbs) | — | — | 56,630 |
| Pin / box tong length (in) | 27.0 / 27.0 | 27.0 / 27.0 | 24.0 / 24.0 |
| Wearpads | 1 × 26.0″ | 1 × 26.0″ | — |
Read the make-up torque as a ceiling, not a target. Per Chapter DS, Section DS-16 of the drilling manual, drilling torque should not exceed 80% of make-up torque. On the 5.5″ Delta 544 that is roughly 41,600 ft-lbs; on the CET54, roughly 42,100. Both manufacturers publish wear tables showing make-up torque falling as tool joint OD wears down, so the figure above applies to a new joint. Ask us for the wear table for your connection.
Why It Is In The String
Where Heavy Weight Earns Its Place
02 // Fatigue
Dampens Bending Stress
By spreading that transition across a length of string rather than one connection, heavy weight reduces the cyclic bending that drives fatigue failure.
03 // Handling
Runs Like Drill Pipe
It handles in the same lengths and with the same equipment as drill pipe, so it adds weight to the string without changing how the crew works.
04 // Wear
Centre Wearpad
The Delta assemblies carry a 26″ centre wearpad, which takes contact against the wall in place of the tube body.
Get in Touch
Operations & Headquarters
Turtle Mountain USA supplies premium drill strings from critical industrial hubs. Contact our teams directly or use the secure specification inquiry form.
Head Office
Eureka, MT
604 1st AveEureka, Montana 59917 Get directions to 604 1st Ave, Eureka, MT 59917 (opens in a new tab)
Texas Yard
Houston, TX
13724 Stancliff StreetHouston, Texas 77045 Get directions to 13724 Stancliff Street, Houston, TX 77045 (opens in a new tab)