Zirconium reinforcement ring issue
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Equipment parameters: Medium: organic acid; design pressure: 3.95 MPa; design temperature: 232°C. There is a DN100 connection port on the shell of the tube box. Initially, it was planned to use zirconium composite plates, with the connection port consisting of carbon steel WN flanges plus zirconium-lined pipes. Now, the client requires that the shell be made entirely of zirconium; as a result, the connection port can only use slip flanges plus reinforcement rings. Is there any problem with this design? 1. Can slip flanges provide a proper seal at such high pressures? 2. Are there any issues with using zirconium reinforcement rings at a pressure of 3.95 MPa?
Why use a loop flange + reinforcement ring instead of zirconium rods or zirconium forgings?
Ah, I would also like to use zirconium forgings. It’s the cost issue – the client insists on the use of reinforcement rings. I want to see if there are any regulations stating that reinforcement rings cannot be used in such cases
The maximum nominal pressure of the loop flange can reach 11 MP – why can’t it be used?
Since the cylinder is made entirely of zirconium, why worry about using zirconium forgings? The cost shouldn’t be much higher than that of a loop flange with a full-zirconium reinforcement ring, right?
Alas, we would like to do it that way too, but the client insists on using slip flanges; if no reason can be found to refuse this, we have no choice but to follow the client’s requirements
Due to the high prices of metals such as zirconium and titanium and the complexity of production techniques, sheets are relatively easy to obtain, as are bars and forgings. However, small batches of pipes are not so easy to get (the batch sizes being too small, pipe manufacturers are unwilling to produce them). So there are often those who sell forgings and bars that are processed into tubes.
It is possible to first calculate the reinforcement for the openings, to determine what the thickness of the DN100 fitting and the thickness of the reinforcement ring should be. If these values are not significantly different from the thickness of the shell, then there should be no problem. Furthermore, due to high pressure and temperature, it is essential to conduct verification calculations for the local stresses in the connections. If the local stress calculation fails, forged pipes must still be used. There is then a good reason to bring this up to the owner.
HG20592-09 welded ring flanges can achieve a pressure rating of 4.0 Mpa, while ASME welded ring flanges can reach 11.0 MPa. The use of slip-on flanges is also an option. As for reinforcement rings, the user can calculate the costs associated with joining plates using ultrasonic testing, as well as the cost of using forged pipes; by comparing these two options, it is estimated that the cost of forged pipes will be higher. If using sheet metal, scrap material can be utilized, after all, a 100-unit connector doesn’t have a large diameter. Zirconium materials are also extremely expensive. DN100 nozzles can also be manufactured by bending sheet metal.