RE: BRAZING WITH SILVER ALLOY

Well, it's a function of operating temperature, and the only way of finding out - safely - is to do a hydraulic test after assembly is complete.

The <...maximum pressure...can withstand...> is only available by testing to destruction. So it's better to look at actual process conditions and find the maximum operating pressure from process conditions, and then test the equipment to a pressure above that. If, for example, the maximum operating pressure were determined by, say, the stall head from a centrifugal pump, then the test pressure needs to be above that, though not as high as the <...maximum...withstand...> pressure.

• In boiler practice, it is commonplace to apply a hydraulic pressure of 1¹/₃ or 1¹/₂ times the design maximum operating pressure while cold, for example, to test for distortion or collapse, and then do a steam test to the maximum operating pressure afterwards, setting the relief equipment accordingly at that time. However, the actual test conditions will depend absolutely upon both local regulation and the ageing of the equipment, which will be brought to the party by the Engineer/Inspector for the insurance company who is witnessing the testing on that organisation's behalf, and who will have done both a visual and ultrasonic test empty beforehand.

So one needs to open a dialogue with the company providing burst/collapse indemnity insurance cover on the equipment in the first instance, and take on its advice prior to arranging any witness testing in pursuit of that cover. There is a lot to be gained by carrying out hydraulic testing to that advice before the witness test, so that the witness test itself does not end in disappointment.

In the UK, a facility's test records are held in a General Register, and there needs to be a written scheme of examination available for it for future reference.

The brazing is traditionally stronger than the copper pipes....the tube will burst in a pressure test before the pipe joint will separate..

...which is why the question of design maximum operating pressure must be addressed, for one wouldn't want to do a maximum withstand test for fear of catastrophic and irreversible self-disassembly of the item under test.

One important thing the forum cannot control is the quality of your joining methods. Therefore, follow PWS's advice.

If in doubt, consult a local qualified Process Engineer.

https://insights.globalspec.com/article/18047/learn-the-difference-rated-pressure-overpressure-and-burst-pressure

You said you brazed with silver alloy but you didn't designate what percentage of silver and other metals are in the alloy. Silver brazing alloy can vary from 2% to 45% in commonly available sticks. The other metals in the stick are also important to know. You haven't said what material is flowing in your heating tubes, is it corrosive to the metals in your silver braze stick?

Try again.