Top tips on brazing


22 June 2022
Focus on a quality finish if you want to keep the customer on side. Picture supplied by Cool Concerns

Haier Europe applied product manager Martyn Nichols explains how to ensure you don’t end up with a hefty bill for poor workmanship.

The quality of the pipework and connections made will have a major impact on prolonging the life of expensive equipment and prevent leaks to systems, whether they be refrigeration, air conditioning or heat pump-based. The F-Gas Regulation places a considerable emphasis on leak reduction and by ensuring that your connections are all that they should be, you are making an important contribution to protecting our planet.

Sad to say there are varying levels of competency in brazing. Poor workmanship can lead to oxidisation inside the pipework and the last thing you want to have to do is to replace an expensive item like a compressor as a result of problems caused by contamination.

Firstly, let’s not forget that brazing should only be undertaken by a competent person certified to do so – and this means getting the right ticket and one that includes an understanding of F-Gas requirements. Secondly, the number of joints in a system should be minimised wherever possible and, thirdly, brazed joints should be preferred to flared joints. 
There is a joy to seeing a nice, tidy joint as it gives an insight to what’s happening inside the pipe. The last thing I like to come across is excessive brazing material on the outside of the pipework. As a rule of thumb, if it looks bad on the outside, on the inside it’s likely to be much worse.

As any experienced engineer will tell you, preparation is the key to competent brazing. Make sure before you start the job you have everything you need to hand. That includes the right size copper pipes, torch nozzle, oxygen-free nitrogen and enough oxyacetylene in the bottles. 

As far as I am concerned the planning is absolutely everything. Make sure too you have the right brazing consumables and the right flux to go with them – those connections have to be as clean as they can possibly be. If the brazing filler rod flows nicely into the joint it should all be tickety-boo inside.

Training and competency have a huge influence on the standard of work. You could be dealing with anything ranging from capillary lines up to large chiller piping. When a chiller has problems – and if it can be traced to a fault with the brazing –  it can leave you seriously out of pocket. 

Oxidisation inside pipework is really bad news for the whole system. Once you’ve sealed the inside it’s near impossible to get this stuff out. After the nitrogen pressure test and your vacuum it could already be game over. The pressure test may move this rubbish down to the liquid line or oil filters and once past them it could attach itself to the electric motors and windings. At best you could end up changing filters sooner than expected. At worst it could mean motor replacements.

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The quality of brazing has a key role to play in maintaining standards. Picture supplied by Cool Concerns

Having said that there are five top tips you can follow to avoid any of these problems. 

Make sure: 

  • you get the preparation right 
  • you use the correct jointing materials
  • your oxyacetylene torch nozzle size is appropriate 
  • you keep surfaces clean of grease and oil
  • oxygen-free nitrogen is purged through the system when brazing.

If you get stuck don’t forget to ask for help. Equipment manufacturers are a great source of information and are happy to advise if you run into problems. There’s also a detailed good practice guide on brazing leak free connections available from the Institute of Refrigeration. 

And, before you begin, make sure you’ve had the right training. Remember, if you aren’t qualified it could leave you with a hefty bill in the future.