2. ACARE Brazing Presentation
“The Art & Science of Brazing”
Instructor: Harold Nelson

3. Always Remember, Safety is #1 and Everyone’s Business!
ACARE Brazing Presentation
Always Remember, Safety is #1 and Everyone’s Business!

4. PERSONAL PROTECTIVE EQUIPMENT
Always wear shaded safety glasses with UV filter with at least a number 2 shade rating
Operators must not wear garments made of synthetic fibers.
Hair below the collar should be tied back during brazing operations.
Heat and flame resistant gloves must be worn at all times.
Heat and flame resistant brazing sleeves with wrist protection must be worn at all times.

5. BRAZING SAFETY
NEVER use matches or a cigarette lighter to light a torch.
Keep your torch in front of you and under control at all times.
Check hoses, fittings and tanks for fuel gas and oxygen leaks regularly.
Keep flammable materials away from brazing areas.
Turn off torches when not in use and place them in the designated location.

6. TANK USAGE AND STORAGE
Fuel gas and oxygen cylinders (storage bottles) must always be handled with extreme care and be property secured. The most common means to secure them is by chaining them in place.
ALWAYS vent or bleed off a small amount of gas or oxygen from a cylinder before attaching a regulator. This blows any dirt or dust off the cylinder valve.
ALWAYS bleed off pressure from hoses and regulators when not in use.
ALWAYS light the fuel gas first during set-up. This prevents back pressuring the fuel line with higher-pressure oxygen.

7. EQUIPMENT
Fixtures for holding parts in correct alignment while brazing (Where applicable).
Access to nitrogen or other inert gas to be used as a purge gas to prevent internal oxidation.
Brush for applying flux (Where applicable).
Heat sinks or heat shields.
A striker for lighting the pilot or torch.
Clean hot water (Where required) for removing flux residue and oxidation.
A tip cleaner for cleaning tips.
Safety equipment.

8. EQUIPMENT

9. Equipment Maintenance & Inspection
Check hoses and fittings for wear, leaks and damage.
Check the orifices in brazing tips to be sure they are not plugged.
Glass covers must be checked for cracks and damage to assure legible readings on the dials and that they are working properly.

10. Equipment Set-up Turn on the fuel gas and oxygen supply valves.
Turn the fuel gas regulator handle.
Turn the oxygen regulator handle.
Light the torch using the striker.
Now slowly open the oxygen valve on the torch. You will need to make proper adjustments to the flame depending on
flame condition. You will do this by adjusting the fuel and oxygen valves to achieve the correct brazing flame.
A neutral flame is best for most copper brazing. Avoid excessively oxidizing flames. A reducing flame is best for joints containing steel.

11. Equipment Set-up

12. Equipment Set-up

13. Affect of Oxide on Alloy Distribution

14. Affect of Oxide on Alloy Distribution

15. Equipment Shutdown
Turn off the fuel gas and oxygen supply valves.
Relieve all pressure from the torch, hoses and regulators. Wait until both gauges read zero and the pilot is out.
Turn off both valves on the torch body.

16. BRAZE PROCESS
A properly brazed joint is obtained by capillary action, which evenly pulls the molten filler metal into the joint.
A well designed joint will facilitate good brazing, but will not guarantee a good joint unless correct procedures are followed.

17. BRAZE PROCESS
The following six basic steps to insure they are producing a quality joint every time.

18. BRAZE PROCESS STEP 1 - GOOD FIT & PROPER CLEARANCE
STEP 2 - CLEANLINESS OF PARTS
STEP 3 - ASSEMBLE AND SUPPORT BRAZE JOINTS
STEP 4 - APPLYING FLUX TO JOINT SURFACES
STEP 5 - BRAZING THE ASSEMBLY
STEP 6 - CLEANING OF BRAZE JOINTS & FLUX REMOVAL

19. Step 1: GOOD FIT & PROPER CLEARANCE
To obtain capillary action. Capillary action is the force that pulls or draws the molten filler metal into the joint.
Strength of the joint. A proper fit will produce a strong joint capable of withstanding the stresses of pressure, thermal expansion and contraction and vibration without failure.
Economy. A well-fitted joint will enable the brazer to produce a quality braze joint in the least amount of time without using more filler metal than necessary.
Make sure the tubing is free of burrs. Burrs could prevent the tube from seating properly, and could also be a problem in the refrigeration system if they break loose inside the assembly.

20. Step 1: GOOD FIT & PROPER CLEARANCE
Connect the tube ends to check the fit: The clearance between the inner and outer part should be.002" to.005" at room temperature and .001" to .005" at brazing temperature for copper-to-copper joints. An “easy slip fit” will make a sound joint if correct procedures are followed. Too much clearance reduces the capillary action and retards the flow of the filler metal. Proper clearance with a thin film of filler metal will produce a leak free joint with high strength.

21. Step 1: GOOD FIT & PROPER CLEARANCE

22. Step 2: CLEANLINESS OF PARTS
Capillary action will work only when the surfaces of metal are clean.
Oil and grease will carbonize when heated; forming a film over which molten filler metal will not flow.
After the parts have been cleaned they must be dry and they should be used as soon as possible to prevent recontamination.
Check the inside of the tubes for oxidation, this contaminate can become dislodged and can cause failure of the refrigeration system.

23. Step 2: CLEANLINESS OF PARTS
Clean vs. Dirty Parts

24. Step 3: ASSEMBLE AND SUPPORT BRAZE JOINT
Parts must be assembled so that joints have a straight, uniform appearance after insertion.
Fixtures should be built to allow the brazer to manipulate assembly to always have Vertical Down Brazing.
Nitrogen or another inert gas purge must be used during the brazing process to ensure internal cleanliness. Nitrogen flowing through tubing during brazing displaces oxygen preventing the formation of oxides on the inside of the tube assemblies.

25. Step 3: ASSEMBLE AND SUPPORT BRAZE JOINT
Nitrogen Set Up
Attach a nitrogen gas hose to the fixture.
Turn on the nitrogen gas regulator and adjust to the proper flow rate.
Verify that there are no restrictions and that nitrogen is flowing freely by checking the exit end of the assembly, unit circuit or coil with a small flame such as a lighter or other suitable method.
If flow is not detected, do not braze the assembly.

26. Step 3: ASSEMBLE AND SUPPORT BRAZE JOINT
Sensitive parts such as valves and solenoids must be protected during brazing.
- Examples for protecting them are chill blocks, water-cooled fixtures and heat sinks.
- The most common heat sink is a wet rag. A wet rag wrapped on a valve during brazing will absorb much of the heat preventing damage to the valve.
Heat Shielding should be applied to sensitive areas such as wires and insulation.

27. Step 4: APPLYING FLUX TO JOINT SURFACES (if needed)
Flux is a chemical compound applied to the joint surfaces before brazing.
Flux on the joint area will shield the surfaces from the air, preventing oxides from forming.
Flux will also dissolve and absorb oxides that form during heating or that were not completely removed during the cleaning process. FLUX IS NOT FOR CLEANING PARTS.
Flux is applied to promote the flow and bonding of the filler metal to the base metals throughout the joint being brazed.

28. Step 4: APPLYING FLUX TO JOINT SURFACES (if needed)
When joining copper to copper with copper- phosphorus alloy filter metal, paste flux is NOT necessary because the phosphorus in the alloy acts as the flux to remove oxides.
(If an alloy with no phosphorus were being used, flux would be necessary even to join copper to copper.)
Flux is necessary when joining dissimilar metal combination such as copper to brass or copper to steel or for repair purposes.

29. Step 4: APPLYING FLUX TO JOINT SURFACES (if needed)
Flux can act as a temperature indicator letting the brazer know when the base metal is
just about hot enough to melt the brazing filler metal.

30. Step 4: APPLYING FLUX TO JOINT SURFACES (if needed)
The flux will bubble as the water boils off. (212° F)
Then the flux will become white & puffy.
(600° F)

31. Step 4: APPLYING FLUX TO JOINT SURFACES (if needed)
The flux begins to lay flat against the metal surface and has a milky appearance. (800°F)

32. Step 4: APPLYING FLUX TO JOINT SURFACES (if needed)
When the flux becomes clear, it is an indication that the metal is hot enough to flow the filler alloy. ( 1100° F)

33. Step 5: BRAZING THE ASSEMBLY
Always use nitrogen to purge the assembly for brazing. Allow sufficient time for nitrogen to purge the part (size and flow dependent). A 20 – 25 SCFH (Standard Cubic Feet per Hour) flow is recommended during brazing.
Protect Sensitive parts such as valves and insulation from excessive heat. When brazing near a valve, insulation, or other braze joints, isolate or protect them from heat to prevent damage or leaks by using heat sinks, water, wet rags or heat shields. Heat sinks and shields should be called out on drawings and process sheets.

34. Step 5: BRAZING THE ASSEMBLY

35. Step 5: BRAZING THE ASSEMBLY

36. Step 5: BRAZING THE ASSEMBLY
Prevents oxides from forming during the brazing operation.
All tubing must be purged with nitrogen during the brazing process.

37. Step 5: BRAZING THE ASSEMBLY

38. Step 5: BRAZING THE ASSEMBLY
Flowmeter

39. Step 5: BRAZING THE ASSEMBLY
Low-pressure nitrogen gas must be flowing through the copper lines when brazing to eliminate scale and oxidation that can cause blockage in a system.
A flowmeter works in conjunction with a regulator to accurately calibrate the outlet pressure while monitoring the flow of gas.
A regulator an be adjusted to deliver low pressure, but by itself, the regulator won’t tell you the nitrogen is flowing.
The flowmeter has a float ball that rises in the flowmeter tube indicating low pressure flow of nitrogen when purging copper lines.

40. Step 5: BRAZING THE ASSEMBLY
Selection of the proper brazing filler material for the joint you are brazing is extremely important. There are a great many filler metals and it is up to engineering to choose the correct alloy for the metals and assembly conditions.
Normally a phosphorus or “phos” - copper rod with 0 % silver is used for joining copper to copper without the use of paste. This is due to the ability of the phosphorus in the alloy to act as a flux.

41. Step 5: BRAZING THE ASSEMBLY
A 5 % phos-copper alloy can be used on looser fitting joints, repair work, tacking and bridging gaps. Loose fitting joints with excessive clearances should be redesigned or have the manufacturing process corrected ASAP. The 5% alloy is only a temporary help until the process or drawing is modified.
Do not use filler metals containing phosphorus to braze ferrous metals, such as steel, because the joint will be brittle and will fail in a short period of time.

42. Step 5: BRAZING THE ASSEMBLY
Joining similar metals - Heat the male portion of the tube and then the Female end that the male is inserted into and allow the joint to melt the alloy.

43. Step 5: BRAZING THE ASSEMBLY
Dissimilar Metals - Heat the good conductor then heat the poor conductor then allow
the joint to melt the alloy.

44. Step 5: BRAZING THE ASSEMBLY
When copper or brass turns a dull red or pink, brazing temperature has been reached. If copper is cherry red or orange it is overheated.

45. Step 5: BRAZING THE ASSEMBLY
3. Sweep the torch between the tube and coupling on all joint sides. This will help bring both parts to brazing temperature.

46. Step 5: BRAZING THE ASSEMBLY
4. Move the flame to the coupling base. Molten brazing filler metal will flow towards the heat. Directing the flame to the coupling promotes flow into the joint.

47. Step 5: BRAZING THE ASSEMBLY
5. Apply the filler metal only when both parts have reached brazing temperature. (The flame may be briefly deflected to the filler metal end to begin the melting process). As tube diameter increases you will need to apply filler metal at several points around the tube circumference to ensure complete joint fill.

48. Step 5: BRAZING THE ASSEMBLY

49. Step 5: BRAZING THE ASSEMBLY

50. Step 5: BRAZING THE ASSEMBLY

51. HOW MUCH FILLER ALLOY IS NEEDED?

52. Step 6: CLEANING OF BRAZE JOINTS & FLUX REMOVAL
Assemblies must be thoroughly cleaned to remove flux residue, loose scale and oxidation. Flux will cause corrosion and eventual joint failure.
WARNING - Allow the assembly to cool before touching it or bums may result. All parts should be allowed to air cool until redness disappears. Water quenching while the parts are still glowing red can cause a joint to crack. If brazing multiple joints, always cool the joints in the order that they were brazed.

53. Step 6: CLEANING OF BRAZE JOINTS & FLUX REMOVAL
Flux can be removed with clean hot water. It may be necessary to use a brush or hand mop. It must be removed completely from the entire joint area. Flux residue may
appear white, clear and sticky or it may be red or green and glassy looking. The hard glassy deposits can be more difficult to remove and they can also temporarily mask.

54. Step 6: CLEANING OF BRAZE JOINTS & FLUX REMOVAL
Use caution when cooling and cleaning assemblies that contain brass and steel parts, such as valve or distributor bodies. RAPID COOLIND IMMEDIATELY AFTER BRAZING CAN CAUSE CRACKS IN BRASS AND STEEL BODIES. Brass and steel must be allowed to cool partially before being cleaned to remove flux. Clean brass and steel when they are warm and not hot.

55. TROUBLESHOOTING
Problem: Alloy lumps or drips during brazing procedures:
• Metal may not be clean.
• Under-heated parts or alloy melted with flame.
• Too much alloy.
Problem: Alloy runs through joints and excessive leaks.
• There is too much clearance. Alloy will flush out of the joint leaving gaps at the top and lumps at the bottom if the space between the metals to be joined is too large. The joint is over-heated. Do not over-heat the joint because time and alloy are wasted. Alloy continues to flow and becomes displaced when over-heating occurs.

56. TROUBLESHOOTING
Problem: Alloy lumps at top of joint creating a "CAP" but does not flow into joint, no
penetration.
• The inserted tube is at brazing temperature and the outside tube is too cool. Be sure to
heat both tubes evenly.
• Flux breakdown. This is caused by excessive heat, flux when overheated can be
saturated with oxides and the braze alloy will not flow
• Clearances are too tight. Some alloys cannot flow into small spaces.

57. TROUBLESHOOTING
Problem: There is excessive alloy running down outside of bell/swage but not into joint.
• The belled tube is at brazing temperature but the male inserted tube is not to
temperature. Remember to heat the inside tube first to conduct heat inside the fitting.
Problem: The formation of oxides.
• The presence of oxides is increased when parts are subjected to excessive heat.
• Use flux when brazing metals other than copper-to-copper using phos-copper alloy.
You are running an oxidizing torch.

58. Factory Brazing School Stand

59. Thank You for Your Attention & Good Training