Fabricated Y-Strainer Design Code

[Leomkel]

Hi all,

I have been reading through the forums related to pressure vessel design codes but I have not been able to find an answer to my question.

I am looking to design a fabricated Y-strainer from standard pipe fittings. My difficulty is deciding on which standard is applicable.

I have purchased fabricated strainers in the past, and on the drawings they state that the strainers are designed to ASME Section VIII, Division 1 and/or CSA B51-19 (I live in Canada). CSA B51 states that at the volume I am looking at, the strainer could be registered as a fitting - but that does not provide guidance for a design code.

The trouble is, ASME Section VIII, Div. 1 states in section U-1(c)(2)(-e) that pressure containing components that are fabricated from generally recognized piping components are excluded from the scope of the division. Would a fabricated strainer still be designed as per Section UW relating to pressure vessels fabricated by welding in order to still receive the "U" marking?

I have read on this forum that you could technically design the strainer per ASME B31.1 or 31.3 since it is fabricated all from standard fittings.

Any direction would be much appreciated, it seems like I could take this in a few different directions for design.

Thanks.

 

[cbPVme]

In my opinion ASME B31.3 would be appropriate as this is a piping component. It would fall under unlisted components and would need to be assessed per paragraph 304.7.2 which essentially requires a proof test in accordance with UG-101 of ASME VIII-1 or a finite element analysis in accordance with Part 5 of ASME VIII-2.

 

This outfit is in your neighbourhood.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[saplanti]

Leomkel,

What you are trying to get away is what you need to do in case you are using one of the pipng code. No escape. Is is going to be a flanged equipment on the pipng and you need to make sure it is working under the qualification of the code.

 

[saplanti]

Why don’t you buy it? In case it does have one of standard diameters of piping you still can buy this product. Why do you need to design? Cheaper to buy.

 

[saplanti]

You have to additionally consider that the strainer will have certain maximum pressure drop. I do not think you can keep the pressure drop similar to the equipment you buy with fitting to fitting construction. Have a look at the cross sections that the manufacturers provide. If you try to meet similar design you need either make it very heavy wall or provide sufficient stiffenening. The stiffeners will ne give you adequate spece to operate on them with the same face-to-face distance that the other manufacturers provide. You will end up with a lot higher cost.

You can check the shapes of the strainers below for the discussion above.

https://www.eaton.com/ecm/groups/public/@pub/@filtration/documents/content/pct_304414.pdf

 

[KevinNZ]

We have made strainers from pipe and fittings,. These are designed as part of total the piping stress model.

 

[saplanti]

KevinNZ, this is a basket strainer not a Y-strainer. I agree thet you can assume the components as parts of the piping. The stress analysis will consider SIF s at the nozzle connections which may end-up with higher wall thickness on the body.

 

[Leomkel]

Thanks for the input cbPVme

Saplanti: Customers specify country of origin for piping components which usually steers us toward a fabricated strainer made from North American fittings. At nearly $3k for a 4" fabricated strainer, it would be cheaper to fabricate and test our own. It is only a tee, two 45* elbows, and two weld neck flanges. Other manufacturers provide these strainers without stiffening and with standard wall thickness fittings.

 

[saplanti]

So you cannot call it y-strainer anymore, and probably you comprimise the pressure drop. In that case you need to provide the pressure drop with/without accumulation to the process engineer. If it was done by others you may be able to use their data.

Nothing is impossible if you pay the price ( in your case the comprimise on the pressure drop).

 

[Trestala]

@Leomkel, agree with @cbPVme. ASME B31.3 can be the base design Code, but have to comply with 304.7.2 which would point to ASME VIII-1 or VIII-2.