FieldEngineersKitEngineering Reference & ASME Code Basis
1. Formula & conversion factors
ASME PCC-1 (Guidelines for Pressure Boundary Bolted Flange Joint Assembly) · ASME B16.5 / B16.47 (Flange bolting count)
Star sequence: groups of four — start → +N/2 → +N/4 → +3N/4 (bolt 1 at top, clockwise)
Round 1 = 0.30 T · Round 2 = 0.60 T · Round 3 = 1.00 T (star) · Round 4 = 1.00 T (circular)
ASME PCC-1 assembly guidance · ASME B16.5 / B16.47 bolt-count helper
This generator builds ASME PCC-1 style star/cross and circular bolt sequences for even counts from 4 to 64. Bolts are numbered clockwise with bolt 1 at the top of the flange. Optional NPS × class selection fills bolt count from the same B16.5 / B16.47 table used by the Bolt Torque calculator. Round fractions (30% / 60% / 100% / circular 100%) match FEK torque screening — confirm wrench targets against the project procedure.
- N (Bolt count) — Number of studs on the bolt circle (even, 4–64). Optional flange preset fills N from B16.5 / B16.47.
- Sequence (Tightening order) — Ordered list of bolt numbers for the selected pattern (star/cross or circular).
- T (Target assembly torque) — Not computed here — use the Bolt Torque calculator for PCC-1 Round 1–4 wrench values.
2. Quick reference lookup table
| Bolts (N) | Pattern name | Tightening sequence |
|---|---|---|
| 4 | Cross | 1 → 3 → 2 → 4 |
| 8 | Star | 1 → 5 → 3 → 7 → 2 → 6 → 4 → 8 |
| 12 | Star | 1 → 7 → 4 → 10 → 2 → 8 → 5 → 11 → 3 → 9 → 6 → 12 |
| 16 | Star | 1 → 9 → 5 → 13 → 3 → 11 → 7 → 15 → 2 → 10 → 6 → 14 → 4 → 12 → 8 → 16 |
| 20 | Star | 1 → 11 → 6 → 16 → 2 → 12 → 7 → 17 → 3 → 13 → 8 → 18 → 4 → 14 → 9 → 19 → 5 → 15 → 10 → 20 |
| 24 | Star | 1 → 13 → 7 → 19 → 4 → 16 → 10 → 22 → 2 → 14 → 8 → 20 → 5 → 17 → 11 → 23 → 3 → 15 → 9 → 21 → 6 → 18 → 12 → 24 |
3. How to use this calculator
- 1
Select bolt count
Choose 4–64 bolts, or pick NPS × class to auto-fill from B16.5 / B16.47.
- 2
Choose pattern mode
Star/cross for Rounds 1–3; circular for the final check pass (or practice either).
- 3
Step through the diagram
Use Next / Prev or tap sequence chips to highlight each bolt in order.
- 4
Copy or export
Copy the arrow sequence text, or export PDF/CSV for the work pack.
- 5
Get torque values
Open the Bolt Torque calculator for Round 1–4 wrench targets at the same joint.
4. Engineering FAQ
Number bolts 1–8 clockwise from the top, then tighten 1 → 5 → 3 → 7 → 2 → 6 → 4 → 8. Finish with a circular 100% pass.
This tool uses the same screening fractions as the FEK Bolt Torque calculator (30% / 60% / 100% / circular 100%). Owner appendices may specify bands such as 20–30% / 50–60% — follow the site procedure when it differs.
Open the ASME PCC-1 Bolt Torque & Tensioning Calculator and carry over the same NPS / class when using the flange helper.