Heat Exchanger hydrotesting 1

[JesseJ]

Going by the UHX & Tema, it states that both the shell side & tube side shall be hydrotested seperately.

I have a unit that the customer requested that the tube side not be rated as it has very low pressure.

According to the code, can we just test the shell side and still be ok?

We are thinking of putting 14.7 (atmospheric pressure) as a minimum on the tube side just to have it rated.

Has anyone ran into this before?

Thanks,

Jess

 

[MJCronin]

Jess,

In my opinion, the question that you are really asking is:

"Is it a good idea to have a STHE with ASME VIII design requirements on one side and "different" quality requirements on the other side ?"

Again, in my opinion, the answer is no...

I believe that it is a good idea to invoke ASME VIII (or whatever vessel code) on both sides of the HX.

This can be done by requesting a minimum design pressure of 15 psig on the low pressure side.

I do not believe that this will cost extra.....but I would like to hear from other engineers on this subject...

MJCronin
Sr. Process Engineer

 

[SnTMan]

JesseJ, it would be permitted for the tubeside to be non-Code. However, tube(s) and tubesheet(s) are part of the shell pressure boundary and would need to be Code. It the HX is built in a Code shop anyway, I'd think any savings from a non-Code tubeside, to the extent possible, would be negligable. You could (and I would) design and fabricate to Code, and not stamp the tubeside. See UG-19.

Regards,

Mike

 

[JesseJ]

Thanks for the input guys.

Our QC checked into it with the NB and they told us that what we need is the ASME/NB ID plate with only the shellside information and a second ID plate with only the tubeside information, but no ASME or NB stamp. We will then only hydro test the shell side and note in the remarks section of the data report, “the tubeside is less than 15 PSIG and outside the scope of the Code”.

Wanted to post this in case anyone else runs across this same issue.

Thanks,

Jess

 

[dineshakabari]

Based on MAWP on tube-side the hydro-test pressure may be considered.

 

[GenB]

External pressure on tubes will be exceeded so stamping and certification is needed
Regardless. The internal on tubes can be exemtpted.

 

[abuanaselmasry]

Thanks for sharing us NB reply. However, still you may code stamp the vessel with 0 design pressure. Please refer to U-1 (c)(2), it says: "Based on the Committee’s consideration, the following classes of vessels are not included in the scope of this Division; however, any pressure vessel which meets all the applicable requirements of this Division may be
stamped with the Certi fication Mark with the U Designator". This will force the workshop to follow other ASME Code requirements (rather than design) related to the fabrication and inspection of the vessel in order to maintain the uniform quality of the HX.

Regards,
M.Salaheldin
Static Equipment Mechanical Design Engineer

 

[GenB]

Internal pressure 0 zero psi at temp. but what about External pressure on the tubes, You are stuck with this one. Ca!lculatioins have to be provided to satisfy the AI.

 

[GenB]

If it will be stamped, I would stamp it at 15 psi at temp. It is safer side ce zero I will not exists. The fluid or gas will excess zero at most times. Regards.

 

[Bmechz]

Since the tubes side pressure is very less and customer doesnt want the hydrotest on the tube side, you perform hydrotest on the shell side and provide client PDR instead of MDR.. That means only a part of the heat exchanger is code stamped..

I think the NB reply is also trying to say the same...

Baijuz