Inside diameter for BW ends ball valve

[cathyvbs]

Hey guys,

I am working in a valve factory. I have a question about the dimension for ball valve bore. The description of the valve is given as follow.

26" 600# ball valves, API 6D design,BW ENDS, STD BORE (.375" WALL THICKNESS), FULL PORT.

According to API 6D, the mininum inside bore for this valve should be 633mm.
But somebody said it should be 25.25"(641.35mm).The calculation is like this. ID=26"-0.75"=25.25"
(According to ASME B16.25, the OD of welding end is 26". )

Your help is highly appreciated!

 

[mzappett]

Dear Cathyvbs,
if the valve is piggable, I mean that inside the pipe that will be welded to the valve ends will pass a 'pig' - a device used to clean the pipeline, the valve bore shall be equal to the I.D. of the pipe.

best regards
Massimo

 

[cathyvbs]

Dear Massimo,
Thanks for your reply.
The valve requires Full port;I think this means piggable. If so, the valve should be in accordance with API 6D(633mm), or should be 25.25"?
Actually, the valve has already been made with 633mm bore. Now our customer said this ID is wrong. They said acc. the order, the ID should be 25.25". They wants to reject these valves.
But our ID meets API 6D Spec. Now I just wants to know if there is something wrong with our design.

Thanks

 

[TechnoZA]

Hi

To me this specification seems contradictory - "Std Bore" and "Full Port" refer to the same thing, but indicate a different requirement. Furthermore, API 6D is a dimensional specification, and if this is requested, it should be adhered to.

Possibly the customer requested a valve and included a specification that he wasn't really familiar with?

 

[BValve]

Dear Cathyvbs,

Full Bore does not mean piggable. It shall be inteprated as per API 6D standard bore dimension = 633 mm.
If customer needs valve to be piggable he shall specify it at enquiry stage and precise full pipe caracteristics.

In your particular case, if your valve description is all what you got at requirement stage, you got half information and should have either specified in your quote that you were offering an API 6D full bore valve or ask for more to customer before quoting.

However, since the valves are specified as butt welded ends, and valve having to be welded to something, you shall in any case ask the question of pipe NB, thickness and grade to check compatibility with applicable codes.

You should have asked - Customer should have specified.

At this stage, few solutions. Customer may accept transition piece you can add to your valve to match pipe ID. In this case, customer shall accept gap into your valve, 1.3% restriction in this case, to be compared with pipe standard tolerances. Please note that if intelligent pigging is used, client will probably reject the valve.

Best regards.

 

[cliff6361]

Not sure where the question of piggable or not came from as this has nothing to do with the origianl question.

The question is what should the end bore be at the butt weld end. The bore of the valve through the ball should be in accordance with Table 1 of API 6D or 633mm dia. (24.9" dia)min. Note API 6D does not define "Full Port". 3.10 defines Full Opening Valve = valve with an unobstucted opening capable of allowing a sphere of the same nominal size as the valve to pass. This works OK in the smaller valves but not true in 14" and larger.

API 6D does not address the BWE dimensions except to refer one to ASME B16.25 under Normative referances. ASME B16.25 requires the inside bore at the weld end be per table 1 or A1 for B or C. However 26" STD wall pipe is not listed in table. Therefore we need to go to ASME B36.10 to get the pipe data for 26" STD wallpipe. 26" pipe is 26.00" OD and STD wall is 0.375 thus the inside at the weld end is 25.25" dia.

Both 6D and B16.25 allow for a transition from the machined BWE ID to the nominal (some times as cast) valve bore. The step back should be 2 times the pipe wall thickness.

 

[pasta1993]

the internal diameter you can use 26" (ball bore) to determinate the schedule dimensions with welded connection pup pieces and the internal diameter, you must know the body ends material & pipeline material ,them ratio yeald strenght can determinate the schedule profile dimensions with a formulas. If you need can you contact me.

 

[JimCasey]

In sizes above 12" US Standard wall pipe has the size in inches as the OD, and 3/8" wall. If you're going to buttweld to US Standard wall pipe, the weld prep at the valve end should match the i.d. of the pipe. This would infer 25 1/4" for the bore of a 26" pipe.

One normally expects the i.d. of a "full port" ball valve to be the same as the i.d. of the pipe.

Does API 6D reference a pipe with different wall thickness? is 3/8 wall thick enough to handle class 600 in a 26" size? This puts you with a pipe wall stress of 48,480 psi at 1440 psi in the pipe (steel class 600 mawp)