Ammonia leakage test
Thread Content
For the ammonia leakage test of the welding joints between the heat exchange tubes and the tube sheet in Appendix A of heat exchanger HG20584, Method B is used. Questions: 1. Why is Method B required? 2. Is Method C feasible? 3. If possible, what method do manufacturing units generally use?
It is clearly specified to use Method B, so of course Method B is used. In the tube bank, the air is distributed in various relatively small spaces, making it difficult to create a vacuum; therefore, the A method using 100% ammonia is not feasible. However, with the 1% ammonia plus air method, due to the lower ammonia concentration, the detection performance of method C is significantly inferior to that of method B. The weld joints between tubes and tube sheets are not comparable to the welds on the container surface.
Most factories choose Method B; Method C is used for large tanks with a large volume, in cases where using Method B would be too wasteful. Since the ammonia concentration is more than 10 times lower than that in Method B, the sensitivity must be much lower as well. Those with higher sensitivity requirements can also use He for leak detection