Category
Piping & Fittings
Subcategory
Components
Applicable standards
3
Issuing bodies
3
Description
Metallic bellows expansion joint for pipework thermal movement & vibration.
Applicable Standards (3)
ASME — 1 standard
ASME B31.3
Process Piping
Piping in petroleum refineries; chemical, pharmaceutical, textile, paper, ore-processing plants and related processing facilities. Default process piping code worldwide.
Key requirements (10)
- Process piping — refining, chemical, pharmaceutical, semiconductor.
- Categories: Normal Fluid Service (default), Category D (low pressure < 150 psig & temp 38–186 °C), Category M (lethal), High Pressure, Severe Cyclic, High Purity.
- Allowable stress: lower of UTS/3, Yield/1.5, etc., from Table A-1.
- Wall thickness: t = P·D / (2·(S·E·W + P·Y)) where Y = 0.4 for ductile under 482 °C.
- Joint efficiency E: 1.0 (seamless), 0.85–0.95 (welded depending on RT).
- Hydrotest: 1.5 × design pressure × (S_test/S_design) — ≥ 10 minutes hold.
- Pneumatic test (when hydro impractical): 1.1 × design pressure with safety analysis.
- Examination: 5% RT for Normal service; 100% RT for Category M and Severe Cyclic.
- Flexibility analysis required when temperature differential > 28 °C and complex routing.
- Stress range allowable SA = f·(1.25·Sc + 0.25·Sh) with f = cyclic reduction factor.
EJMA — 1 standard
EJMA Standards
Standards of the Expansion Joint Manufacturers Association
Metallic bellows expansion joint design, manufacture and installation.
EN/CEN — 1 standard
EN 14917
Metal bellows expansion joints for pressure applications
European bellows expansion joint standard (alternative to EJMA).