Weight of a stainless steel pipe: formula and table
The weight of a 12Х18Н10Т pipe is calculated by the formula M = π × (D − s) × s × 7.9 / 1000, where D is the outer diameter, s is the wall thickness, and the result is obtained in kilograms per metre.
A ⌀38×1.5 pipe weighs 1.36 kg per metre, that is 8.15 kg per six-metre length, and there are about 736 m of such pipe in a tonne. Below — the formula and tables with which you can calculate without a calculator.
Below — the formula, the calculation of round and profile pipe, a table by diameters and the conversion of linear metres into tonnes: this is enough to manage without an online calculator.
Formula for round pipe
M = π × (D − s) × s × 7.9 / 1000.
Explanation of the symbols: π ≈ 3.14159; D — outer diameter in millimetres; s — wall thickness in millimetres; 7.9 — the density of stainless steel in g/cm³; division by 1000 converts grams into kilograms.
Why (D − s). The area of the wall is the area of a ring. It is more convenient to calculate it along the midline, whose diameter equals the outer diameter minus the wall thickness. Hence the difference in the formula.
The order of calculation without a calculator:
- Subtract the wall from the diameter.
- Multiply by the wall.
- Multiply by π.
- Multiply by 7.9 and divide by 1000.
Example ⌀38×1.5. 38 − 1.5 = 36.5. Multiply by 1.5 — we get 54.75. Multiply by π — 172.0. Multiply by 7.9 and divide by 1000 — 1.359 kg per metre. Check: six metres give 8.15 kg.
Field estimate. For a quick estimate in your head, the expression (D − s) × s / 40 works. For ⌀38×1.5 this is 1.37 kg against the exact 1.36 — an error of less than one percent. For ⌀108×3 the estimate gives 7.88 against 7.82 kg. Such accuracy is enough to understand the order of the weight, but for a delivery note calculate by the main formula.
Profile pipe
M = 2 × (a + b − 2s) × s × 7.9 / 1000.
Here a and b are the sides of the profile in millimetres, s is the wall thickness. The expression in brackets is the perimeter of the midline, and the multiplier 2 takes into account the two walls in each direction. For a square, a and b are equal, and the formula is the same.
Example 40×40×1.5. 40 + 40 − 3 = 77. Multiply by 2 — 154. Multiply by 1.5 — 231. Multiply by 7.9 and divide by 1000 — 1.825 kg per metre. A six-metre length — 10.95 kg.
Example 60×40×2.0. 60 + 40 − 4 = 96. Multiply by 2 — 192. Multiply by 2.0 — 384. Multiply by 7.9 and divide by 1000 — 3.034 kg per metre. The length — 18.2 kg.
Error. The formula calculates a profile along the midline and does not take into account the rounding of the corners, so it gives a slight overestimate — usually less than one percent. For calculating a batch this is insignificant; for an exact delivery note, check against actual weighing.
Table by diameters
| Pipe, mm | 1 m, kg | 6 m, kg | Metres per tonne |
|---|---|---|---|
| ⌀16×1.5 | 0.54 | 3.24 | 1852 |
| ⌀19×1.5 | 0.65 | 3.91 | 1535 |
| ⌀25×1.5 | 0.88 | 5.25 | 1143 |
| ⌀32×1.5 | 1.14 | 6.81 | 881 |
| ⌀38×1.5 | 1.36 | 8.15 | 736 |
| ⌀42.4×1.5 | 1.52 | 9.14 | 657 |
| ⌀50.8×1.5 | 1.84 | 11.01 | 545 |
| ⌀50.8×2.0 | 2.42 | 14.53 | 413 |
| ⌀76.1×2.0 | 3.68 | 22.07 | 272 |
| ⌀101.6×2.0 | 4.94 | 29.66 | 202 |
| ⌀108×3.0 | 7.82 | 46.91 | 128 |
What can be seen from the table. The same outer diameter with a different wall gives a different weight: ⌀50.8 with a wall of 1.5 mm weighs 1.84 kg per metre, with a wall of 2.0 mm — 2.42 kg. The difference in the metres per tonne is even more noticeable: 545 m against 413 m. That is why an order always states both the diameter and the wall.
For profile pipe the reference points are these: 20×20×1.5 — 0.88 kg per metre, 40×40×1.5 — 1.83 kg, 50×50×1.5 — 2.30 kg, 60×40×2.0 — 3.03 kg.
Linear metre into a tonne
Metres per tonne = 1000 / mass of a metre. Mass of a batch = mass of a metre × length.
- 200 m of ⌀38×1.5 pipe: 1.359 × 200 = 272 kg.
- 1 t of ⌀38×1.5 pipe: 1000 / 1.359 ≈ 736 m, that is about 122 lengths of 6 m.
- 1 t of 60×40×2.0 profile: 1000 / 3.034 ≈ 330 m, that is 55 lengths.
- 500 m of 40×40×1.5 profile: 1.825 × 500 = 912 kg.
- 100 m of ⌀25×1.5 pipe: 0.88 × 100 = 88 kg.
How to apply this. If the order is in metres while logistics is calculated in tonnes, convert the length into mass before submitting. If it is more convenient to order a tonne, divide 1000 by the mass of a metre and you get the length that can actually be delivered. Rounding always goes down to a whole number of lengths: 736 m is 122 full six-metre lengths and a remainder.
A common mistake is to calculate a pipe as a round bar of the same diameter. A ⌀20 round bar weighs 2.48 kg per metre, while a ⌀20 pipe with a wall of 1.5 mm weighs about 0.7 kg. The second mistake is to take a density of 8.0 for all grades: for 430 this will give a noticeable discrepancy.
Frequently asked questions
How much does 1 metre of 12Х18Н10Т pipe weigh?
It depends on the diameter and the wall. ⌀25×1.5 — 0.88 kg, ⌀38×1.5 — 1.36 kg, ⌀50.8×2.0 — 2.42 kg, ⌀108×3.0 — 7.82 kg. It is calculated by the formula π × (D − s) × s × 7.9 / 1000.
How do I calculate the weight of a 50 mm pipe?
For ⌀50.8 with a wall of 1.5 mm: (50.8 − 1.5) × 1.5 × 3.14159 × 7.9 / 1000 = 1.84 kg per metre. With a wall of 2.0 mm the same pipe weighs 2.42 kg. The diameter without the wall does not determine the weight.
How many metres of pipe are there in a tonne?
⌀38×1.5 — about 736 m, ⌀50.8×2.0 — about 413 m, ⌀108×3.0 — about 128 m. The number is obtained by dividing 1000 kg by the mass of a metre, and in lengths — by also dividing by 6.
How does the weight of a seamless pipe differ from a welded one?
With the same diameter, wall and grade the mass of a metre is the same: the formula depends only on the geometry and the density. In practice the weight of a batch may differ because of wall tolerances: different methods of production have their own.
How do I calculate the weight of a profile pipe?
By the formula 2 × (a + b − 2s) × s × 7.9 / 1000, where a and b are the sides of the profile, s is the wall. For 40×40×1.5 this is 1.825 kg per metre, for 60×40×2.0 — 3.034 kg.
Why does the calculation not match the delivery note?
Because of deviations in diameter and wall, differences in density between grades, and which mass is stated — theoretical or actual. A discrepancy of a few percent is considered normal.
Does the grade affect the weight of a pipe?
Slightly. 316L is heavier than 304 by about 1%, ferritic 430 is lighter by about 2.5%. For a single pipe this is fractions of a percent of the mass; for a batch of tens of tonnes — noticeable kilograms.
Place an order for pipe
On the GCX exchange round pipe of AISI 201, 304 and 316L with a diameter of 16–108 mm is traded, and profile pipe — square 20×20–50×50, rectangular 40×20 and 60×40. An order fixes the grade, the size, the surface and the shipment week.