What design code and orifice designation for this relief valve? 2

[chemks2012]

Dear all,

I wish to buy Spiraxsarco relief valve, model SV604AS [see attached] for one of our clients.
It is for saturated steam and the required vent area is 178mm2. Therefore, valve 20mmX32mm with orifice size of 230mm2 looks OK.
However, normally API/ASME valve has orifice designation. I asked supplier [spirax Sarco] but they said this valve is not designed as per API/ASME and hence no orifice designation.

However, from the attached brochure, nothing is clear. Not sure of the design code of this valve and its orifice designation. Any pointers please?

Thanks in advance.
KS

 

[chemks2012]

Apologies, I forgot to attach file.

As can be seen on page 1, it refers to ASME/API for seat tightness.
As can be seen on page 4, the vent area is 230mm2.

But no info on overall valve design code.

 

[don1980]

There are lots of different types of valves in the global marketplace. Some are API 526 valves (D-T orifice designations), some are ASME certified, and many others that are neither ASME certified or API526 type valves. As a relief designer you have a world of choices. The vendor catalog will tell you the valve type and all the various certifications. It's your responsibility to have a basic understanding of these options and know what is needed for a given application. The vendors can help advise you on this, but it's your decision and responsibility as the relief designer. Here's a bief summary of the basics.

API 526 valves: These are the valves that are built to the API526 manufacturing standard. The orifices are designated with a letter code D-T. They're flanged valves, easy to work on, and built to uniform face-to-face dimensions. These are the most widely used safety valves in the petrochem industry. They're mechanically strong and they available in the most widely used range of sizes (1x2 to 8x10). If you need a valve smaller or bigger than this, then it won't be an API526 valve. That's perfectly OK. This is just one of many type of valve that you can choose from.

ASME Sec VIII certified valves: This simply means that the valve has been flow tested, per the ASME Sec VIII procedure. It therefore has a known flow coefficient, published in the National Board "Red Book". Any valve manufacturer can perform this test and have their valves "ASME Sec VIII certified". There's no association between "ASME certified" and "API526". Those are two separate things. All API526 valve happen to be ASME certified, but there are tons of other valves (non-API526) that are also ASME certified. Many of these are tiny valves that you can fit into your pocket - of course you can't do that with an API526 valve. When do you need an ASME Sec VIII certified valve? You need that when you're protecting ASME Sec VIII equipment. For example, if you're protecting a piece of pipe or a pump then ASME Sec VIII certification isn't necessary. The valve you choose will likely be ASME Sec VIII certified, simply because so many valves are. That's OK, you can use it but it's not necessary in that specific case.

Seat tightness to API527: API527 is simply a standard for seat tightness. It defines the uniform testing procedure for seat-tightness and the allowable leak rate. Any valve can be tested and certified as compliant with this seat tightness standard.

CE certified: These are valves that are certified for use in European Union countries, per the requirement in the Pressure Equipment Directive (PED). PED is the high-level goverance requirements for protecting a wide range of pressurized equipment, including vessels and equipment used in petrochem plants.

In this particular case, you have specified a Sarco valve that is CE certified. It passes the API 527 seat tightness test, but it's not built to the API 526 standard, and it not ASME certified. Is that OK? The answer depends on where this facility is located, whether the equipment is fabricated to ASME code, and owner's preference (do they want to use API526 valves). If you're installing this valve in a European facility, then this is an acceptable choice on your part. If you're installing the valve in a North American facility (ASME code jurisdiction) on an ASME pressure vessel, then this isn't the right valve choice.

 

[chemks2012]

Hello don1980,

Such a fantastic post from you once again! Thanks a ton..

In fact, the valve is for protecting the steam line and is located at the downstream of pressure reducing valve to protect the line when pressure reducing valve fails.

Safety valve along with other equipment will be sourced in EU country and will be used in the East African country.

As I understand from your post, we don't need ASME certified valve as its on the steam line but not sure what's required in East Africa.