Basket strainer as pressure vessel 2

[Unotec]

I have been trying to talk to ABSA (in Alberta) regarding filer pots aka basket strainers and whether they are regulated as pressure vessels or not. If they require scheduled testing etc... Unfortunately I have not been lucky enough to get a clear answer.
Typically they are installed in the suction side of the pumps, a few on the discharge side. The ones on the discharges would see pressures no higher that 40-50 psi.\
Their size makes me think they might be excempt, since the volume is under 1ft3.

Does anybody have an idea on how these are regulated?

 

[vesselfab]

Seen them both ways, both foreign and domestic (USA)

 

[dcasto]

Whats the difference, call them piping and you need to inspect reguarly, call them vessel you need to inspect.

Pick what ever is easiest on you. The point is to set a standard and follow it.

 

[doct9960]

unotec,

See if this link would help...

http://www.pveng.com/m/content/article.php?content_id=6#DI

 

[Unotec]

YESSS! Thank you

 

[saplanti]

unotec,

Strainers are replacable component in the piping systems and they are to filter debris to protect important downstream equipment such as pumps, turbines etc..

In the important systems there is a need for measurement in the pressure differantial of both side of the strainers to see if it is blocked or in the acceptable level of cleanless.

As far as I know there is no design code for strainers. I guess, the manufacturers design them for the blocked condition to protect the equipment, and provide pressue/head loss coefficient for the strainers to able to give a direction the process design engineer to calculate the total losses accurately.

Mainly, the responsible plant maintenance team record the pressure differantial regularly and decide for cleaning in case the pressure differantial is in an unacceptable level or plan the cleaning in accordance with the expected pressure differantial.

Hope it helps.

Ibrahim Demir

 

[chief]

The only real pressure you are going to get in a basket strainer is when it is choked. Then you have a vacuum pressure to deal with and a cavitation problem with your pumps. Fit a suction gauge on your pumps and record the trend, which indicates the need for cleaning.Consider filter boxes as part of the piping for inspection purposes. OEM will provide paperwork required.

Offshore Engineering&Design

 

[moltenmetal]

ABSA will require that the basket strainer have a Canadian Registry Number (CRN) as a category H fitting if it is used in pressure piping. Even if it should be above 1.5 ft3 and in theory fall under ASME, it is no different than any other large PIPING component if it is indeed used in piping.

A filter is distinct from a strainer. Filters can often be large relative to the lines they're installed in, and hence sometimes are registered separately as pressure vessels when they fall into the ASME size rules. Like all components in piping systems, it becomes a judgment call when something is considered a pressure vessel rather than a piping component. The unwritten guideline to use is stored volume: if the thing represents a large fraction of the stored volume of the overall pressure-retaining system, it's a vessel. 24" piping connecting two huge pressure vessels is clearly piping, but a 24" diameter filter housing with 1" lines running into and out of it is probably a vessel.

 

[Unotec]

Thank you people,

As it turns, the strainers we have, depending on the location, have fallen in all categories: Pressure vessel, Fitting and No CRN required.

Saplanti & Chief, thanks for your points of view. However, most manufacturers here in Canada actually have their designs and units registered as pressure vessels. One example I have in my plants, and it is common in the industry, is the strainer in the inter tank transfer pumps where the line pressure is between 30-50psi. There is the potential of transferring fluids such as condensates or liquids at temperatures >65ºC. Thus this makes it a pressure vessel.

Thank you all for the valuable comments.

 

[saplanti]

Unotec,

I agree with calling the housing body of the strainer as pressure vessel or pipe fitting. Of course, whatever you included into the system is has to retain pressure, temperature and transfer the external forces available on the system. Therefore, they are subject to the system design code required.

In my post I basically concentrated on the strainer itself not he housing.

Regards,

Ibrahim Demir

 

[garnet1]

One more comment. Refer to CSA B-51 to determine how it should be registered. Another note is that if there are no pressure vessels either directly or indirectly linked to the strainer, ie: in a storage tank facility etc. then it is outside ABSA durisdiction and need no registration at all. Most basket strainers are registered as Cat H fittings unless they are designed for over 600 PSI or are over 1.5m3.

 

[garnet1]

Sorry, that would be 1.5ft3 not 1.5m3 in my last post. Typo.