Plug Valves API 599 / API 6D 3

[vaibhavdhumal]

As per API 599 plug valves shall meet requirements of B16.34, Even though they have specified their required body thickness.
API 6D also covers plug valves which are also designed as per B16.34 or other equivalent standard.
Face to face Dimensions are also similar in both the standards.
Can anyone tell what is fundamental difference between two standard.


----VD

 

[vaibhavdhumal]

Can anyone guide me on below confusion?

 

[Danlap]

First of all, taken into a note that both API and ASME are generated and improved by End user, manufacturer and professional (independent scholar).
As well as other standard (NORSOK - Norway, Werkstoff - Germany, etc.) it is always in favor on material commonly used by local manufacturer (in this case America for ASME).
So you can see that there are wide coverage of material P/T Rating (ASME wise) covered in ASME 16.34
Nobody (even independent professional) would imposed such standard if there is no available material in their area for manufacturer to be used.

API 6D along with ASME B16.34 is general. Those two standards along with it sub standards (API 599 for Plug Valves, API 608 Metal Ball valves, etc.) are complementing each other.
API 599 and its friends are more conservative in this regards in comparison with ASME B16.34.
You can see from ASME B16.34 the wall thickness calculation is really basic, however the end result is only a bit thinner compare to API 599. Do not jump into conclusion that then it would be less resilient.

I would say:
Use only API 599 if only you can ensure below:
1. The material as per API 599 is; Quote "Table 2—Minimum Body Thickness (Inches): Materials Except Ductile Iron and Heavy-wall (API 600 Wall) Stainless Steel" Unquote
2. For non special service application (very low / very High temperature; very corrosive medium). Or for commodity valve only

And consider ASME B16.34 for:
1. Specific known (ASME) material
2. And assurance that the design of your Pipe Class are still within ASME B16.34 P/T rating table(s). This is something that API 599 itself do not have, and would refer to other standard(s)
In other words different valve (except Check Valve) may have same Class, Size and Minimum Body wall thickness. However, when it is applied under different Operating P/T range and using different material. Then you may end up by asking the manufacturer for a 'better' material.

PS:
Do not forget to incorporate NACE, Corrosion allowance, etc. for your valve selection

Hopes that provide some insights.
Regards,
MR


Greenfield and Brownfield have one thing in common; Valve(s) is deemed to "run to fail" earlier shall compared to other equipments

 

[vaibhavdhumal]

Thanks a lot MR.

one of your statement is unclear
"2. For non special service application (very low / very High temperature; very corrosive medium). Or for commodity valve only"

can you please explain you want to talk about special service or non special service.

Also commodity valves means?


Regards,
VD

 

[Danlap]

Hi VD,

Commodity valves meaning (may be different for others)are;
1. Valves that are built using standards material (Body WCB, WCC, S316, etc. - Trim S316 w/o Stellite, standard soft seat NBR, EPDM, PTFE, etc.), which
2. Normally have the highest turnover (End users are aware that these valve are likely to be replaced within 3-5 years or less), thus
3. the valves normally ready to be picked up from manufacturers shelf almost at any time.
So, these kind of valves are to be installed in non critical service (which fail to run is not expected). Either process wise, or related to other critical equipment (turbine, pumps, etc.)

Apology for my poor English,
My previous statement meaning that Valve selection on many occasion do have to conform with P/T rating (among others requirement), which API 599 suggest that it should be referring to other standards (name a few 16.34, 16.42, 16.5, etc.).
So special service is temperature (or pressure) and or process medium that is not recommended to be borne only by 'commodity' valves without applying other standards.
[ul]
[li]For instance shall it is really corrosive medium, than NACE to be taken into account --> Commodity trim might be used with an addition of Stellite or Chrome (for instance).[/li]
[li]If scaling built up is to be expected, than one could consider body material of Monel 400 (B127 Gr. N04400) or others.[/li]
[li]Etc.[/li]
[/ul]

Those additional condition, you would not find it black and white in API 599 only.

Hopes that clarify,

Regards,

Greenfield and Brownfield have one thing in common; Valve(s) is deemed to "run to fail" earlier shall compared to other equipments

 

[pdp123]

Agree with your post.

In addition I have to say that API6D is for Long distance Pipeline and API599 for Piping.
Also it depends on the Client requirements to select a specific standard.

Kindly share your thoughts regarding this.

Thanks!