Mismatch - Pipe Flange to Pump fLANGE

[Chance17]

I am working with a client and there are pipe-to-pump size mismatches.
Pipe suct = 2"-150" connectd to Pump suct = 1.5"-150#
Pump disch=1.5"-150" connectd to Pipe Disc = 1"-150#
Apparently the flange bolts are a size smaller to make everything align.
From the Client's view, it works, it does not leak and it has been that way for 10+ years.
The pump operating pressure is about 60% of flange rating.

What arguments can I present to the Client for facility modification ??

 

[moltenmetal]

If the service is Category D (non-hazardous) and the design pressure of the system is, as you said, less than 150# class, the owner can choose to do nothing. Obviously you would not replace the existing system "in kind" because it's just plain bad practice, but there'd be little justification for ripping it out and replacing it just because it looks bad.

If the service is "normal fluid service", meaning something at least somewhat hazardous if released, a person would have to demonstrate that the new "designed flange" combination (i.e. the combination of mis-matched components) was safe despite the thinner studs. 10+ years of service won't be any comfort if and when the joint fails and people get hurt.

Obviously the available gasket seating stress isn't a problem since the joint doesn't leak. The fact that the useable raised face area is actually SMALLER in this configuration than it would be for flanges of the same size doesn't hurt either. If you use a gasket requiring far less than the maximum seating stress that ANSI flanges are designed for(i.e. an o-ring or the like), and you use a smaller gasket area, and a design pressure of only 60-ish percent of the 150# rating, you can get by with fewer or smaller bolts and thinner flanges when you do the ASME VIII Appendix 2 calculation. Do an Appendix 2 calc using the new geometry and stud sizes and design pressure and see what you get. That might help you decide what to do.

 

[Artisi]

After 10 years - why bother?

 

[bingopin]

Any possibility that these are reducing flanges?

 

[racookpe1978]

The client is losing a lot of money (pump impeller wear too!) with that sudden and sharp break in flow sizes at both suction and discharge.

Energy costs alone make the change in pipe sizes - suction and discharge side - cost-effective.

Best pump performance is smooth pipe straight inlet for 14-20 x pipe diameters, upward-facing reducer (if needed) and smooth discharge.

 

[Chance17]

For the record, I am going to answer my own question.
The facility should be modified because the assembly pressure rating can not be evaluated by established pipe codes

 

[Artisi]

Why not?