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Steam Pipe Sizing

lb/hr → Pipe Size · Low / Medium / High Pressure · Schedule 40/80

When to use: Use to size steam supply and condensate return pipes from steam load in lb/hr and system pressure class. Based on ASHRAE and industry steam pipe capacity tables. Low pressure = 2–15 psig (residential/institutional), medium = 15–100 psig (commercial), high = 100+ psig (industrial). Accounts for pressure drop of approximately 1/16 psi per 100 ft of pipe.

Steam System Parameters
Design steam demand
lb/hr
Capacity Table (selected pressure)
1/2"10 lb/hr
3/4"25 lb/hr
1"55 lb/hr
1-1/4"110 lb/hr
1-1/2"180 lb/hr
2"380 lb/hr
Minimum Pipe Size
2-1/2"
nominal pipe size
Results
Steam Flow500 lb/hr
Equivalent Heat Load485 MBH
Equivalent Cooling40.42 tons
Minimum Pipe Size2-1/2"
References
ASHRAE Handbook – HVAC Systems & Equipment
Latent heat of steam ≈ 970 BTU/lb
Allow 1/16 psi/100 ft pressure drop
Condensate lines: size for gravity return flow