The 2026 edition of ASME PCC-1, the guideline for assembling pressure boundary bolted flange joints, is out. Here is a plain summary of what changed and what it means when you order studs, nuts and washers.
Tightening patterns
The star and modified star pattern is now the main sequence (App F, Table F-6.1.1.1-1). The legacy cross pattern from the 2019 edition moved to App J (J-6) as an accepted alternative. Read more in Tightening Patterns Explained.
Single stud replacement
A new Appendix G covers replacing studs one at a time on pressurized joints, including conditions that rule it out and a risk scoring method. See our Single Stud Replacement Pre-Check.
Relaxation passes and retorque
J-4 was rewritten. It separates pre-start-up retorque, start-up retorque (300–450°F or within 24 hours), retorque after a thermal cycle, and live tightening, with cautions for each. See Relaxation and Retorque Passes.
Double nutting and self-loosening
New J-8 covers preventing self-loosening: bolt load first, then double nutting with the jam nut inside, then positive locking. See Double Nutting and Jam Nuts.
Bolt elongation and controlled disassembly
J-3 (elongation) and J-7 (controlled disassembly by turn-of-nut) were revised. Try the Bolt Elongation Calculator.
Training and records
Sections 2, 3 and 13 and App A were rewritten. Owners set the skill level needed, and App A defines four levels with endorsements for powered equipment. Section 13 now lists what joint assembly and historical records may include, and App R covers risk-based records and tear-off tags. Try our Flange Joint Tag.
Washers, tensioning and flexibility
App M adds a caution that some ASTM F436 washer sizes interfere with flange spot faces. Q-4.5 sets out tensioning passes for 100% and 50% tool coverage. P-4.2 expands on bolt flexibility and conical spring washers. See Through-Hardened Flange Washers, the Tensioning Pressure Calculator and Belleville Washers and Live Loading.
Glossary
App I adds and revises many terms, including relaxation pass, start-up retorque, double nutting and target torque. See the Bolted Joint Glossary.
What it means for ordering bolting
- Double nutting needs longer studs and matching jam nuts.
- Tensioning needs at least 1D extra stud length on the tool side.
- Through-hardened washers need to clear spot faces; specify the type and size.
- New studs and nuts are recommended up to 1-1/8 in. where bolt load is controlled.
- Ask for mill test reports so your joint records are complete.
How Patriot Bolt can help
Patriot Bolt manufactures stud bolts, heavy hex nuts, jam nuts and flange washers from certified bar, with mill test reports on every order. Send us your bolting list for a quote or call (281) 581-0176. We do not perform field bolting, training or stud replacement.
