Category
Piping & Fittings
Subcategory
Building Services
Applicable standards
2
Issuing bodies
1
Description
ASME B31.9 piping for low-pressure HVAC, hydronic, fuel oil and steam services in buildings.
Applicable Standards (2)
ASME — 2 standards
ASME B31.9
Building Services Piping
Low-pressure piping in industrial, institutional, commercial and public buildings (HVAC, plumbing, light steam).
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.