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Copper Tube Joints Working Pressure Solder or Brazing Joints Based on ASME Standard B31.9

HVAC Systems and Components
Engineering Materials

Working Internal Pressure for Copper Tube Solder or Brazing Joints Based on ASME Standard B31.9

Copper tube is usually joined by soldering or brazing socket end fittings. Brazing materials melt above 1000°F and produce a stronger joint than solder.

The table below lists soldered and brazed joint strengths. ASME Standard B16.22-specified wrought copper solder joint fittings and ASME Standard B16.18-specified cast copper solder joint fittings are pressure rated the same way as annealed Type L copper tube of the same size. Health concerns have caused many jurisdictions to ban solder containing lead or antimony for joining pipe in potable-water systems. Lead-based solder, in particular, must not be used for potable water.

Alloy Used
for Joints
Internal Working Pressure, psi
Water and Noncorrosive Liquids and Gasesa
Sat. Steam
and
Condensate
Nominal Tube Size
(Types K, L, M), in.
Service
Temp.,
°F
1/4
to
1
1-1/4 to 2
2-1/2
to
4
5 to 8a
10
to
12a
1/4
to
8
50-50 tin/leadb solder
(ASTM B32 Gr 50A)
100
200
175
150
130
100
150
150
125
100
90
70
200
100
90
75
70
50
250
85
75
50
45
40
15
95-5 tin/antimonyc solder
(ASTM B32 Gr 50TA)
100
500
400
300
270
150
150
400
350
275
250
150
200
300
250
200
180
140
250
200
175
150
135
110
15
Brazing alloys
melting
at or
above 1000°F
100 to 200
d
d
d
d
d
250
300
210
170
150
150
350
270
190
150
150
150
120

aSolder joints are not to be used for
(1) Flammable or toxic gases or liquids
(2) Gas, vapor, or compressed air in tubing over 4 in., unless max. pressure is limited to 20 psig.

bLead solders must not be used in potable-water systems.
cTin/antimony solder is allowed for potable-water supplies in some jurisdictions.
dRated pressure for up to 200°F applies to the tube being joined.

Related:

References

  • ASHRAE Handbook of Fundamentals, 2021 Inch-Pound Edition