Contents
About this tool
The Process Piping (B31.3) tool checks one line of process piping: the fluid service category, the allowable stress at the design temperature, the minimum wall the design pressure needs and the pressure the selected pipe can carry, and the hydrostatic, pneumatic or initial service leak test. It can also compare a measured thickness with the required thickness.
Built on ASME B31.3-2016, the text on file. ASME B31.3-2024 is current and has not been compared; the tool will be upgraded when that text is available. The page, the report and this manual say so.
The stresses are those of the 2016 Table A-1M. Appendix A values change between editions: confirm them against the edition your project is built to before relying on a result.
B31.3 covers piping inside refineries, chemical and process plants and terminals. Liquid transfer pipelines between facilities, and the tank-farm and terminal piping that belongs to them, fall under B31.4 — use the Pipeline tool.
Quick start
- 1Load a sample or fill in Identification. Choose SI or US units; records are kept in SI.
- 2Section 1: the fluid service, design pressure and temperature, the minimum temperature, and whether the fluid is flammable or toxic and the conditions severe cyclic.
- 3Section 2: size, nominal wall, mill under-tolerance (12.5 % for most pipe), material, longitudinal joint and allowances.
- 4Section 3: the test type, test temperature and pressure at the high point, the elevation to the low point, the hold time, and (optional) the lowest component rating. For a pneumatic test, the relief valve set pressure.
- 5Section 4 (optional): the lowest measured thickness and your corrosion rate.
- 6Tick the checklist; save and print.
Fluid service (300.2)
| Category | Conditions | In the tool |
|---|---|---|
| Normal | everything not in another category | all checks |
| Category D | nonflammable, nontoxic, not damaging to tissue; ≤ 1 035 kPa (10.35 bar); ≤ 186 °C; not below −29 °C | checks all four; permits the initial service leak test (345.7) |
| Category M | very highly toxic; designated by the owner | flags Chapter VIII and the sensitive leak test (345.8) |
| High Pressure | designated by the owner | out of scope (Chapter IX) |
- Severe cyclic conditions (305.2.3): the pipe must have Ej ≥ 0.90; API 5L only Grade B seamless or SAW with Ej ≥ 0.95, and X42 to X52 seamless.
- Minimum temperature (323.2.2): the tool shows the material’s curve of Figure 323.2.2A and warns below −29 °C for carbon steel. The impact test exemption depends on thickness; check it.
Pressure design (304.1)
| Quantity | Equation |
|---|---|
| Pressure design thickness | t = P D / 2(S E W + P Y) (3a) |
| Minimum required thickness | tm = t + c (2) |
| Nominal wall needed | tm / (1 − mill under-tolerance) |
| Maximum design pressure of the pipe selected | P = 2 S E W (T − c) / (D − 2 Y (T − c)), with T = tn (1 − tolerance) |
| Factor | Source |
|---|---|
| S, basic allowable stress | Table A-1M at the design temperature, linear interpolation |
| Ej, longitudinal weld joint quality factor | Table A-1B: seamless 1.00; ERW 0.85; API 5L SAW double butt 0.95; A312 EFW double 0.85, single 0.80; 100 % radiographed 1.00 |
| W, weld joint strength reduction factor | 1.0 below the temperatures of Table 302.3.5 |
| Y | 0.4 (Table 304.1.1, t < D/6, ferritic to 482 °C, austenitic to 566 °C) |
| c | corrosion and erosion allowance plus thread or groove depth |
- If t ≥ D/6 or P/SE > 0.385 the tool warns: 304.1.2 (b) requires special consideration.
Materials in the tool
| Material | Sy, MPa | Data to |
|---|---|---|
| A106 B, A53 B, API 5L B, A333 Gr 6 | 241 | 450 °C |
| A106 C | 276 | 425 °C |
| API 5L X42 / X52 | 290 / 359 | 204 °C |
| A312 TP304 / TP316 | 207 | 400 °C |
| A312 TP304L / TP316L | 172 | 400 °C |
The minimum yield strengths are those listed in Table A-1M and are used only for the test pressure limit of 345.2.1 (a). Above the last temperature the tool stops: those are creep-range values where W and Y change.
Leak test (345)
| Test | Pressure | Other rules |
|---|---|---|
| Hydrostatic (345.4) | at every point at least 1.5 P × ST/S (eq. 24) | water, or a non-toxic liquid with flash point ≥ 49 °C |
| Limit (345.2.1 a) | may be reduced so the hoop stress on the minimum wall does not exceed yield at the test temperature, nor 1.5 × the component rating | the tool checks the low point against this |
| Pneumatic (345.5) | 1.1 P to the lesser of 1.33 P and 90 % of the 345.2.1 (a) pressure | relief valve set at most PT + lesser of 345 kPa and 10 %; only where the owner considers hydrostatic impracticable |
| Initial service (345.7) | operating pressure, service fluid | Category D only, at the owner’s option |
| All | hold at least 10 min, then examine (345.2.2 a) | after heat treatment; consider brittle fracture at low test temperature |
- The test pressure is entered at the high point; for a hydrostatic test the tool adds the static head to find the low-point pressure.
- Category M also needs a sensitive leak test (345.8).
Measured thickness (optional)
Section 4 compares the lowest measured thickness with the pressure design thickness t (without allowance), gives the pressure the measured wall supports, and divides the margin by the corrosion rate. This is simple arithmetic, not an API 570 assessment: API 570 (not on file) governs in-service inspection, retirement thickness and intervals.
Saving and the report
- Fill in Identification (company, tank or item ID, location) and the record type: Just for research stays private to you; Official is visible to your company.
- Calculate & Save stores the inputs and results in the
pipeB313Calcscollection. - Print / PDF report opens a printable page of everything on screen: identification, the standard and edition, each section’s inputs and results, and any notes. Use Save as PDF in the print dialog. The report states the edition (B31.3-2016, upgrade due to B31.3-2024) and that the allowable stresses must be checked against the project edition.
Limits
- ASME B31.3-2016 basis; the 2024 edition has not been compared.
- Straight pipe under internal pressure only. Bends, branches, flanges and other components (304.2 – 304.7), external pressure, flexibility and sustained-load stresses (319, 302.3.5) and occasional variations (302.2.4) are not checked.
- Eleven materials, below the creep range. Other materials and higher temperatures need the full Appendix A.
- For pipelines and terminal transfer lines use the Pipeline (B31.4) tool; for valve shell and seat tests use the Valve Test (API 598) tool.