A tubing data sheet is the one-page spec for a given size, weight, grade and connection of oilfield tubing. It gives the pipe’s outside diameter, wall thickness, inside diameter, drift, coupling OD, capacity and displacement, plus its tensile, burst and collapse ratings. Once tubing has been in a well, the line to read is the inspection class and remaining body wall the ratings were calculated at. The ratings hold only if the joint still has that much wall, and remaining wall is what an EMI scan measures.
What’s on a tubing data sheet
Production Technology’s tubing primer describes tubing by four things: grade, outside diameter, weight and connection. A typical sheet from a tubular rental company adds the rest.
| Line | What it means in the field |
|---|---|
| OD (nominal size) | The outside diameter of the pipe body. The most common production sizes are 2-3/8”, 2-7/8”, 3-1/2” and 4-1/2”. |
| Nominal weight | Average weight per foot, connection included, in lb/ft. For a given OD the weight sets the wall thickness, so “2-7/8 6.5#” tells you the wall without saying it. |
| Wall thickness and ID | The ID is the OD minus twice the wall. You use it for pressure loss, velocity and volume. |
| Drift | The diameter of a 42-inch-long mandrel that has to pass through the joint, and so the largest OD of any tool, pump or plug you can count on running through the string. |
| Connection | EUE (external upset end) or NUE (non-upset). EUE is more common because the upset puts extra wall where the threads are cut, so threading doesn’t weaken the body. |
| Coupling OD | The biggest OD on the string. It decides what fits inside the casing and how much clearance you have for a cable or a fishing tool. |
| Grade | API 5CT tubing grades include J55, C75, L80, N80, C90 and P105. The number is the minimum yield strength in thousands of psi, so L80 and N80 both have an 80,000 psi minimum yield. The letter refers to chemistry and sometimes heat treatment. |
| Range | Joint length. Range 2 runs 28 to 32 feet. Range 1 is 20 to 24 feet. |
| Tensile, burst and collapse | Tensile is the pull the pipe body can take. Burst (internal yield) is the inside-over-outside pressure difference that fails it. Collapse is the outside-over-inside difference it can take without permanent deformation. |
| Capacity and displacement | Capacity is the fluid volume inside the pipe, in barrels per foot. Displacement is the volume of the steel itself. |
2-3/8, 2-7/8 and 3-1/2 tubing specs side by side
These figures come from three Quail Tools tubing specification sheets for L80 EUE 8-round tubing, Range 2. They’re the sizes and weights you’ll see on most Permian rod-pumped and flowing wells.
| Line on the sheet | 2-3/8” 4.70# L80 | 2-7/8” 6.50# L80 | 3-1/2” 9.30# L80 |
|---|---|---|---|
| OD | 2.375 in | 2.875 in | 3.500 in |
| Nominal wall | 0.190 in | 0.217 in | 0.254 in |
| ID | 1.995 in | 2.441 in | 2.992 in |
| Drift | 1.901 in | 2.347 in | 2.867 in |
| EUE coupling OD | 3.063 in | 3.668 in | 4.500 in |
| Inspection class on the sheet | Premium Class 80% | Premium Class 80% | Premium Class 80% |
| Remaining body wall for that class | 0.152 in | 0.174 in | 0.203 in |
| Tensile strength | 82,020 lb | 114,080 lb | 163,180 lb |
| Burst capacity | 10,240 psi | 9,660 psi | 9,290 psi |
| Collapse capacity | 8,950 psi | 8,000 psi | 7,400 psi |
| Fluid capacity | 0.00387 bbl/ft | 0.00579 bbl/ft | 0.00870 bbl/ft |
| Fluid displacement | 0.00170 bbl/ft | 0.00236 bbl/ft | 0.00339 bbl/ft |
On these sheets the drift is 0.094 in (3/32”) smaller than the ID for 2-3/8 and 2-7/8, and 0.125 in (1/8”) smaller for 3-1/2. A tool built to the ID won’t pass a drift-checked string. And the coupling, not the pipe, is the widest thing in the hole: 3.668 in on 2-7/8 EUE against a 2.875 in body.
Capacity is the line you’ll use most on location. A string of 2-7/8 6.5# hung at 8,000 feet holds about 46 barrels (8,000 × 0.00579). Its steel displaces about 19 barrels (8,000 × 0.00236), which is what the hole gives up or takes when you pull or run it open-ended.
Why the ratings assume less wall than the sheet’s nominal wall
Look at the notes on those sheets and you’ll find two different wall figures.
The first is the mill tolerance. The sheets note the tubing was “ordered to API 5CT 87.5% RBW.” RBW means remaining body wall. In other words, new tubing can come from the mill as thin as 87.5% of nominal wall at its thinnest point, so a brand-new joint of 2-7/8 6.5# can legally have about 0.190 in at its thinnest spot instead of 0.217 in.
The second is the inspection class. The performance columns on these sheets are listed at “Premium Class 80%,” with a remaining body wall of 0.174 in for 2-7/8. That’s 80% of 0.217 in. The burst, collapse and tensile numbers are what a joint with that much wall left can carry.
Barlow’s formula, the standard first estimate for internal pressure, puts burst in direct proportion to wall thickness: P = 2 × stress × wall ÷ OD. Plug in 80,000 psi yield, the 0.174 in Premium wall and the 2.875 in OD and you get about 9,680 psi, close to the 9,660 psi on the sheet. Take the wall down further and the burst rating comes down with it, roughly one for one. A joint at 60% remaining wall has roughly three quarters of the burst capacity of a Premium joint.
Quail’s own disclaimer says the wear-condition values “do not represent or imply acceptable operating limits.” Whether a thinner joint goes back in the hole is the operator’s call.
Where tubing wall goes in a Permian well
Pulled tubing rarely loses wall evenly. Rod wear cuts a groove on one side where the rod string rubs. CO2 and H2S corrosion leave pits and patches. Sand and high-rate production erode the inside. Each of these takes metal from a few inches of one joint while the rest of the string looks fine.
The data sheet describes a uniform pipe. An 8,000-foot string of Range 2 tubing coming out of the hole is about 250 different joints, each with its own worst spot. The joint that sets the string’s real burst or tensile limit is the one with the least wall, wherever it is.
More on the wear mechanisms in our guides to rod pump tubing wear and what EMI tubing inspection finds.
Reading an inspection report against the data sheet
An electromagnetic inspection (EMI) scan runs the full length of every joint and flags wall loss, rod wear, pitting and other defects. To turn that trace into a decision, you need the data sheet beside it.
- Start from nominal wall. Get it from the data sheet for the exact size and weight. 2-7/8 tubing comes in more than one weight, and each has its own wall.
- Ask how loss is reported. A percentage of nominal wall and a measured remaining thickness are different numbers. A 20% loss on 2-7/8 6.5# leaves about 0.174 in, the Premium figure.
- Remember the mill tolerance. New pipe can be 12.5% under nominal. A reading that looks like wear on a fresh joint may be the mill.
- Match the class to the job. Sheets are usually printed at Premium (80% RBW). If you plan to run a joint with less wall than that, you need ratings at that lower wall, not the Premium ones.
- Check the drift and the threads separately. A wall-loss grade says nothing about dents, bends or scale that restrict the ID, or about thread condition. Our OCTG inspection guide covers what drift and thread inspection add.
Color-band thresholds on used pipe vary between buyers and inspection companies, so put the remaining-wall number you’ll accept on the work order instead of a color name.
Spot checks vs full-length scans
An ultrasonic reading gives an exact wall where the probe sits but can miss a rod-wear groove between readings. A full-length electromagnetic scan covers the whole body of each joint, so the usual pattern on used tubing is EMI to find the worst spots and UT to confirm them. Our ultrasonic thickness testing guide compares the two.
EMI tubing inspection on the lease
Site Safe Solutions runs EMI tubing inspection at the wellhead or on the lease in the Permian Basin. The scan is non-contact, it works on tubing down to small diameters, and it finds wall loss, rod wear and corrosion along each joint. You get digital trace records, so you can compare each joint to its data sheet and see how fast a string is wearing from one pull to the next. If you’ve got tubing coming out of a well, tell us the size, weight and joint count and we’ll plan the scan around your rig schedule.
