Vessel Code?

[tuanjim]

Hi,

I'm a junior engineer so I apologise if this is an obvious question but I am wondering if anyone out there could help clear up an issue I'm having with defining what exactly is considered a pressure vessel - or more to the point, at which stage does a pipe etc. become a vessel?
My basic problem is that I've been asked to determine whether we need a certificate of compliance for a process analyser that my company makes. The thing is that while it is designed to and does operate at pressures well in excess of 15 psig at times, it is basically a flow cell whose internal dimensions open to flow are not much greater than the incoming 1/4" tubing?
So my question then is: Does such an instrument classify as a 'vessel' and, if so, how would I go about codifying it and ascertaining its compliance?

Cheers

 

[sshep]

tuanjim,
Sounds like you are probably fine.

Check out:
ASME section VIII, Div 1, U-1 (c)(2)(e)

and related parts of the code to see what is allowed- i.e. when you can get by without a stamp. I can't remember the verbage exactly, but I am pretty sure this gets small filters and other "piping like" components out of needing relief valves, etc.

best wishes, sshep

 

[EGT01]

Tuanjim,

I have no experience with providing a "certificate of compliance" but I wonder why you seemed to jump to the conclusion that it must be related to pressure vessels. Maybe there is some other code or standard to which you should be considering to certify compliance. You might want to check your competitors or other similar instruments to see if they are offering a certificate of compliance.

 

[sbush]

Your vessels is outside of the scope (U-1) of the ASME code, Section VIII, Division 1. If you have access to the code, look under Scope U-1. It is very clear in your case.

S. Bush

http://www.water-eg.com

 

[katmar]

The codes do specify what they cover, but your legal liability will be defined by the law of the countries where you sell your equipment.

For example, here in South Africa a pressure vessel is defined as having
A pressure greater than 40 kPag, AND
A diameter of greater than 150 mm, AND
the product of pressure and volume is greater than some number (which I forget at the moment)

If it meets these criteria it has to have a log book, regular inspections etc, etc.

Whether your equipment is a pressure vessel or not, you will still be obliged to design it to withstand the pressure it is rated for (and be able to prove you have done so) in order to prevent common law liability.

 

[tuanjim]

Thanks very much everyone

 

[Rosalynn]

Hello,
If ASME B31.3 applies to your jurisdition, this may be more appropriate for your device. It sounds to me more like a piping component than a vessel. If the individual components used are in compliance with B31.3, and they are assembled in compliance with B31.3, then you've got a pretty good start.
B31.3 applies to chemical and refinery piping. B31.1 applies to steam boilers, and there are other codes and standards for oil and gas field piping (here in Canada it's a CSA standard), so the applicable code will depend on where you wish to use your device.
If I were assembling such a device where I live, I'd be going to the local "boilers branch" to get the appropriate application forms to submit the design for review and approval. Then I'd include it with the marketing documentation so that potential purchasers would know it was "legal".

 

[NewfieEng]

Tuanjim,

I recently had this same debate about coding of vessels for a blowcase that I was designing for a compressor station. The conclusion I came to from the ASME codes in the US was that as long as the blowcase was made with certified piping components and had no internal parts (ie. filters, straightening vanes, diverters....) than it did not have to be a certified pressure vessel. In essence it was just a wide spot in the pipe made totally off piping components. It did not matter what size the inlet pipe was or the pressure rating (as long as the piping components were designed for the given pressure).

I am not sure if this is the case with the vessel you are dealing with but this is the conclusion I came to for my vessel.

Gavin