A soldered copper tube joint places the tube inside a fitting cup, leaving a narrow annular space that filler metal can enter when the materials, preparation and process are suitable. This calculator converts entered values and reports simple arithmetic only; it does not prescribe or validate a soldering process.
Torch Soldering Copper Interactive Calculator
Enter a diameter, lower and upper temperature, gap and comparison factor. Results are conversions and bookkeeping, not heating time, capillary pressure, flux margin or process guidance.
Equation Used
- Diameter and gap values are supplied directly by the user.
- The diameter conversion uses exactly 25.4 millimetres per inch.
- Temperature difference is clamped at zero if an upper value is below a lower value.
- The comparison factor is supplied directly and has no inferred physical meaning.
- Alloy, flux, tube and fitting standards, clearance suitability, wetting, surface tension, contact angle, heat transfer, losses, joint fill, strength, pressure rating, code compliance and hot-work safety are omitted.
Tube, Fitting Cup and Capillary Space
The Copper Development Association's Copper Tube Handbook describes a tube inserted into a fitting cup with a narrow space between the overlapping surfaces. With compatible materials and suitable preparation, molten filler metal can enter that space by capillary action.
The handbook also treats cleaning, flux selection, assembly, heating and filler application as parts of a controlled installation procedure. A schematic alone cannot establish joint quality.
What This Calculator Does
The tool converts an entered diameter from inches to millimetres, subtracts an entered lower temperature from an entered upper temperature without allowing a negative result, converts an entered gap from millimetres to micrometres and multiplies the temperature difference by an entered factor.
It does not calculate heating time, capillary pressure, solder flow, flux performance or joint suitability.
Conversion and Bookkeeping Relations
DeltaT = max(0,Tupper-Tlower)
gum = 1000 gmm
S = f DeltaT
S is only an entered-value comparison product. Degrees Celsius used for a temperature difference are numerically equal to kelvins, but S is not energy, power, heat or a process prediction.
Worked Arithmetic Example
For an entered diameter of 0.5 in, lower temperature of 20 °C, upper temperature of 240 °C, gap of 0.075 mm and factor 1.0, the outputs are 12.70 mm, 220 °C difference, 75 µm and a scaled difference of 220.0 °C.
These values do not determine torch settings, heating time, alloy behavior, flux activity or joint quality.
Model Boundary
- Mechanical arrangement: tube insertion into a fitting cup, an annular capillary space and filler-metal flow when the specified materials and procedure are suitable.
- Calculated: two unit conversions, a nonnegative subtraction and multiplication by an entered factor.
- Not calculated: tube or fitting standard, actual clearance, alloy solidus or liquidus, flux activity, wetting, surface tension, contact angle, capillary pressure, heat capacity, thermal conductivity, torch power, flame distribution, heat loss, heating time, temperature field, filler quantity, penetration, voids, cooling, metallurgical condition, strength, pressure rating, leakage, code compliance, potable-water compliance, fire risk or safe work.
Frequently Asked Questions
Does the temperature difference predict heating time?
No. The calculator contains no mass, heat capacity, heat-transfer coefficient, source power, efficiency or loss model.
Is the gap conversion a capillary-pressure result?
No. It is only millimetres converted to micrometres.
Does the factor represent a particular torch?
No. It is an arbitrary entered comparison factor.
Does the drawing prove that solder will fill the joint?
No. Wetting and fill depend on the actual materials, preparation, geometry and procedure.
Can these outputs establish a pressure rating or code-compliant joint?
No. Use applicable codes, standards and authenticated product data.
Is this operational hot-work guidance?
No. Soldering can be hot work with fire, fume and burn hazards. Follow site requirements, product instructions and qualified professional guidance.
References
- Copper Development Association, Copper Tube Handbook: fitting-cup assembly, capillary space, flux, heating and soldered-joint process context.
- Copper Development Association, Soldered Joints: Applying Solder: capillary-action description and manufacturer-instruction boundary.
- U.S. Occupational Safety and Health Administration, Hot Work: soldering as an ignition-producing hot-work activity and associated controls.
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