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

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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 Gases^a						Sat. Steam and Condensate
	Nominal Tube Size (Types K, L, M), in.						Sat. Steam and Condensate
	Service Temp., °F	1/4 to 1	1-1/4 to 2	2-1/2 to 4	5 to 8^a	10 to 12^a	1/4 to 8
50-50 tin/lead^b 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/antimony^c 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.

References

ASHRAE Handbook of Fundamentals, 2021 Inch-Pound Edition