Valves inspection ANSI B16.34 and API 6D

[carletes]

Hello all!

I am looking for the tests and inspection that are commonly specified when purchasing ball, gate, globe etc valves for any service (water, steam and other). Reviewing ANSI B16.34 it seems to require only pressure testing for all valves, and other NDT only for special rate valves. Am I right? If a valve is standard class only pressure test is required?
Moreover, I have found in Internet that other codes such as API 6D are more restrictive with the inspections required to valves. Could any tell me about its main differences with ANSI B 16.34?

Thank you very much for any help.

 

[JNieuwsma]

Regarding NDE and and ASME B16.34
You are correct. NDE, either radiography or alternatively, if agreed to by the customer, ultrasound, is required only for special class valves.

Regarding test standards
The following valve standards all apply to testing, or at least cover testing among other topics (these are the ones I’m most familiar with; there are many others):
ASME B16.34
API 598
API 6D
MSS SP 61
MSS SP 82

There are several parameters to consider when disussing test requirements:
1) What tests are required (shell, seat, backseat)
2) Test fluid
3) Test pressure
4) Test duration
5) Allowable leakage (if any)

Specific details depend on which stanadard is invoked, as well as valve type, size, and class. API 6D applies specifically to valves in petroleum pipelines. The API 6D seat test requirements are very strict; no leakage is allowed. On the other hand, ASME does not specifiy allowable seat leakage. Rather, B16.34 refers users to another standard such as API 598 or SP 61.

 

[carletes]

Thank you for your help, JNieuwsma!

So, if I have understood your commnts, there is not any code that establishes which tests and inspections must be performed? I mean, any code that depending on pressure, diameter, service etc establishes if penetrant liquids are necessary or magnetic examination etc. Is it always a customer's decision? If not code, do you know of any publication that manages this issue or gives recommendations?

Thanks again.

 

[JNieuwsma]

While several standards are explicit in stating pressure test requirements, off the top of my head I'm not aware of any standard that explicitly states when NDE is required for valves (or in other words, in what circumstances is a special class valve required.)

Noting from your header that you're in the chemical industry, I refer you to ASME B31.3 "Chemical Plant and Petroleum Refinery Piping" (I'm looking at an old edition--1993).

Paragraph 302.3.3 defines casting quality factors. By default, WCB steel castings have a quality factor Ec=0.80. Casting quality factors may be increased to a maximum of 1.00 by supplementary NDE (radiography, magnetic particle, dye penetrant, ultrasound) according to table 302.3.3C.

Of course, the the next question that logically follows would be in what circumstances is an increase in the casting quality factor Ec required. Unfortunatley I'll have to leave that one open for now. I'd love to spend the morning wading through B31.3, but maybe someone who's more familiar with the document than I am can pitch in while I try to keep the boss happy!

Hope this help.
Jonathan Nieuwsma

 

[smh345]

I am not aware of any national or international standard that determines the level of NDE required.
There are many end user specifications that define the level of NDE for various class ratings, a very common one being the Shell MESC specifications. The Shell MESC's are often used by other companies as a benchmark standard to determine NDFE requriements according to the level of risk from pressure rating, material and service.

 

[RXH]

API 6A is one specification that spells out NDE (among other) requirements depending on the severity of the service as defined by a Product Specification Level (PSL) of 1, 2, 3 or 4. You could use it as a guideline. You may need to define your own levels of severity depending on what your services are.

For "standard service" (you need to define this) valves, in most cases all you need to do is call out the industry standard, i.e, API 600 for refinery gate and globe valves, API 608 or API 6D for ball valves, API 609 for butterfly valves, etc. These standards will provide the minimum requirements for test and inspection, usually by reference to API 598 or MSS-SP-61 or other similar standard.

When a valve falls into the next higher category, then you may need to specify additional requirements. This is usually a user call-out depending on experience.

What types of valves and what services are you concerned with? If you provide some details, I'm sure Forum members will be able to provide more concrete recommendations.

 

[carletes]

Thank you all for your help!

My problem is that I am preparing a general inspection and testing specification for all manual and power-actuated valves of any Combined Cycle Power Plant!! So, most of the services include water, steam and fuel gas with pressures up to 150 bar and temperatures up to 550ºC (you can see, all ratings).
I don't know Shell specifications smh345 refers to (I am from Spain). Do you know in Internet where can I find those or similar recommendations?
Finally, unfortunately I don't have all codes and regulations I'd like to, but for example, having a look at API 6D I do not find a word about testing apart from pressure testing. Others like API 600 or API 608 say something about (I mean when is recommendable to perform each test)? If so, perhaps I could press my bosses to buy them.

Best regards

 

[JNieuwsma]

If it's a power plant you're talking about, then ASME B31.1 might help. I'm out of the office so I don't have access to a copy.

 

[NGiLuzzu]

Carletes,
sometimes I work with Shell specifications, but I never heard agout "smh" documents (we usually refer to "MESC SPE" and "DEP" documents...). In any case, you may contact Shell Global Solutions B.V. at

http://www.shellglobalsolutions.com/.

Having to prepare test procedures, but from the Manufacturer's side, I also have some difficulties: as a matter of fact, we often risk to perform tests on new valves (sometimes re-testing after maintenance of installed ones) that are far from the real service conditions, as they're based upon "the paper" (Standards, Specifications, etc...) more than upon Plant experience: there are so many commercial passages that we rarely can deal with End-User Techincians directly.

In general terms, in order to write you own Specification, I'd suggest you:
1) to identify, knowing your Plant's needs, the "safety mission" of your valves, that is the functions they must perform (what pressure, temperature, internal and external allowable leak rates, closing and opening times, etc...);
2) to give each one of those requirement a priority level and so state a clear order among them;
3) to find the simplest ways, with the means available to you, to verify the compliance to the requirements, as near as possible to the actual service conditions.

You might also contact the Engineering Companies that have designed and built your Plant and try to see the Reference Documents they used when they bought the valves...

Hope this helps, 'NGL