List the bare valves, flanges and steam traps with size and quantity. The page computes how much heat they lose, what that fuel costs each year and how fast removable insulation jackets pay back.
Pre-sizing and estimating tool: results do not replace design, calculations or reports signed by a licensed professional, nor verification against the applicable codes and standards.
Bare items and with removable jackets, summing each row’s quantity.
Length of bare pipe of the same size that loses as much heat as one item.
Take this page’s results to another calculator with the fields already filled in.
Cash flow of the improvement: investment in year 0 and annual savings escalated at the rate entered, discounted at the MARR.
The calculation report gathers this page's inputs, results, equations, assumptions and references, with fields for project, engineer and revision. The full report also includes the charts and interpretations, in color. In the print dialog, choose Save as PDF.
Quite a lot: at 366 °F (150 psig steam), a bare 4" Class 150 flanged gate valve loses about 4,900 Btu/h, the same as 4 ft of bare 4" pipe. Over 8,760 hours that is roughly $430 a year of fuel for that one valve at $8/MMBtu. In the example, 44 bare items lose about 108,000 Btu/h and condense 127 lb/h of steam.
For 2" to 24" flanged gate valves it uses the tabulated areas of ASTM C1129 (Class 150 and 300); a bare 6" Class 300 valve equals 5.6 ft of bare pipe. For Class 150 flange pairs it computes faces, rims and nuts from ASME B16.5 dimensions. For steam traps it uses the area entered in its own field, and any row can take a measured area in the list’s 4th column.
A cover of technical fabric with an insulating blanket, closed with hook-and-loop or buckles, that comes off for maintenance and goes back on. In the example, 1 in jackets cut 90% of the loss and save about $8,500 a year for a $5,700 investment: payback in about 8 months. On steam lines, paybacks under a year are common (DOE Steam Tip Sheet 17).
Type, size and number of bare items (a walkdown with a spreadsheet does it), steam pressure or fluid temperature, ambient temperature, wind and the hours per year the line stays hot. Fuel price per MMBtu and boiler efficiency come from the fuel bill or the steam cost calculator.
It depends on the type. Float and inverted bucket traps can be jacketed; thermostatic traps (bimetallic or balanced pressure) must not be insulated, because they need to lose heat to close; thermodynamic traps only with the maker’s own cap. When in doubt, follow the trap manual.
Loss depends strongly on surface emissivity, wind and the area used. This page uses an emissivity of 0.9, the ASTM C1129 default, and the standard’s own areas; the DOE savings table (Steam Tip Sheet 17) gives values about 25% to 30% lower for the same valve, because it starts from other assumptions. For large decisions, confirm with thermography or a supplier survey.
It assumes the bare surface at fluid temperature and the jacket as homogeneous insulation; seams and gaps make a real jacket lose a bit more. It does not include the bare pipe left next to flanges for bolt removal, which raises the real loss. The biggest practical risk is the jacket not going back on after maintenance.
Important notice: Indus Metrics tools produce estimates and pre-sizing results from the data you enter and from published engineering methods. They do not replace design, calculations or reports signed by a licensed professional engineer (PE), nor verification against the applicable codes, standards and regulations, such as OSHA rules and the ASME codes. Material and fuel properties vary: check manufacturer data or your own process analyses before deciding. By using this site you agree to the Terms of Use.
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