PCC-1-2026 moved the legacy cross pattern to Appendix J and made the star pattern the main sequence. This page explains each pattern, when it is used and how many passes it takes. Diagrams are our own illustrations. Values are for reference; confirm against the current edition of the governing standard. Send us your bolting list for a quote or call (281) 581-0176.
Related: Flange Tightening Pass Table · Flange Bolt Tightening Patterns · Flange Gap Log · All technical docs
Illustrations only. Use the bolt order in ASME PCC-1-2026 Table F-6.1.1.1-1, or PB-TD-201 for the legacy cross pattern.
Star and modified star (Pattern #1, F-6.1.1)
Bolts are tightened in a star order across the flange so load builds evenly. The modified star brings the first bolts up in steps (20–30%, then 50–70%) before taking the rest to 100%. A second 100% pass may be needed for spiral wound, double-jacketed or problematic joints. Finish with circular check passes until no nut turns. Bolt order is in PCC-1 Table F-6.1.1.1-1.
Quadrant (Pattern #2, F-6.1.2)
The flange is split into four quadrants, worked in a cross or circular order. It suits larger flanges and several tools working together.
Circular (Pattern #3, F-6.1.3)
Four bolts at 12, 3, 6 and 9 o’clock are brought up in passes, then every bolt is tightened in a circle until no nut turns. It is for hard gaskets, not gaskets that are sensitive to uneven loading. Several tools working at once extend it to softer gaskets (F-6.1.3.3).
Legacy cross pattern (J-6)
The cross pattern from PCC-1-2019 is still an accepted alternative. It is shown on our Flange Bolt Tightening Patterns sheet (PB-TD-201).
Large bolt counts (J-5)
For 48 bolts or more (often from 36), bolts can be grouped, about a 30° arc per group, and each group treated as one position in the star order.
Ring joints (F-8)
Ring type joints and lens rings need several pattern passes and several circular passes. Large RTJ flanges (over NPS 12) may need four pattern passes and six or more circular passes. Gap checks are recommended.
Soft gaskets such as PTFE (F-9)
Load slowly, use multiple check passes (often three or more), monitor gaps, and where several tools stay in place allow 10–15 minutes between passes.
New procedures (F-7)
A new or faster pattern should be backed by experience or by testing. A hydrotest alone is not enough evidence.