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What failed steam traps cost a US plant
A steam trap is one of the cheapest parts in a plant until it sticks open. We counted what that means for a site with 300 of them.
US$68,000
of gas a year escapes through 30 failed steam traps
- 857 tof CO₂ a year from steam nobody uses
- US$2,300a year wasted by each trap stuck open
The problem
A steam trap has one job. It lets condensate and air out of the steam line and keeps the steam in. While it works, nobody thinks about it. When it fails open, live steam blows straight through into the condensate return and the boiler burns more gas to replace it.
Traps fail quietly. One that is stuck open looks the same from the walkway as one that works, and the extra gas is spread across the whole monthly bill. The US Department of Energy found that in steam systems left without maintenance for three to five years, 15 to 30% of traps had failed.
We took a mid-size plant with 300 traps on 100 psig steam, running 8,000 hours a year. One trap in five has failed. Half of those failed closed, which backs up condensate and causes its own trouble. The other half are stuck open, and those are the ones we costed.
The working
Each line follows from the one before it. The inputs and their sources are listed further down, so you can redo it with your own numbers.
300 steam traps, one square each
Stuck open, blowing live steam 30Failed closed, backing up condensate 30Working 240
Traps blowing live steam
traps × share failed × share stuck open
= 300 traps × 20% × 50%
= 30 traps
Steam lost
open traps × loss per trap × hours
= 30 traps × 52.8 lb/h × 8,000 h
= 12,672 thousand lb a year
Fuel burned to make it
steam lost × heat per thousand lb ÷ boiler efficiency
= 12,672 klb × 1.02 MMBtu ÷ 80%
= 16,157 MMBtu a year
What the gas costs
fuel × gas price ÷ heat per thousand cubic feet
= 16,157 MMBtu × US$4.37 ÷ 1.036
= US$68,152 a year
Carbon
fuel × natural gas CO₂ factor
= 16,157 MMBtu × 53.06 kg CO₂/MMBtu
= 857 t CO₂ a year
The fix
A trap survey is quick work. A technician checks each trap with an ultrasonic probe and a thermal camera and records it in a register with a tag number, so every trap has a status and a location. Replacing a trap costs a few hundred dollars. Here each open trap wastes about US$2,300 a year, so most pay for themselves within months.
The register is what keeps the saving. Without a yearly check, the failure rate drifts back to where it started.
What would change the answer
Orifice size and steam pressure matter most. A 1/8 inch orifice at 100 psig is a common case, and a larger orifice or higher pressure loses a lot more steam.
Gas prices move too. US$4.37 per thousand cubic feet is a cheap-gas example, and at higher prices the loss grows in proportion.
Inputs and sources
- Steam traps on site300 trapsAssumption for a typical site
- Share failed20%US DOE Steam Tip Sheet 1: 15 to 30% of traps fail in systems left unmaintained for 3 to 5 years
- Share of failed traps stuck open50%Assumption for a typical site; the rest fail closed
- Loss per open trap, 1/8 in orifice at 100 psig52.8 lb/hUS DOE Steam Tip Sheet 1, leaking trap table
- Steam hours8,000 h a yearAssumption for a typical site
- Heat in 1,000 lb of steam from 200 °F feedwater1.02 MMBtu/klbSteam tables, 100 psig saturated
- Boiler efficiency80%Assumption for a typical site
- US industrial natural gas price, Oct 20254.37 USD/McfEIA industrial price series
- Heat content of natural gas1.036 MMBtu/McfEIA
- Natural gas CO₂ factor53.06 kg CO₂/MMBtuUS EPA GHG Emission Factors Hub
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