Classification of Swing Check Valve Opening Type per API 6D Clause 4.4

[ilkerdburhan]

Hello, I'm relatively new to this topic, so please excuse me if my question seems basic — I just want to make sure I understand the standard correctly.

We have a swing check valve designed in accordance with API 6D. I’m trying to correctly classify the valve under clause 4.4 (Valve Opening Types), but I need clarification between the following subclauses:

• 4.4.2 Full opening
• 4.4.3 Reduced opening with circular opening
• 4.4.4 Reduced opening with non-circular opening

Here is the situation:

• The valve’s bore dimensions comply with Table 1 of API 6D.
• The seat diameter matches the bore diameter, which would normally indicate a full-opening design.
• However, due to the internal construction, the disc does not open fully during operation limiting roughly %25 of the the effective flow area. Because of this it is clear that it's not full openning.

It looks like 4.4.4 is the correct opening type however I can't be sure of it.

What are your opinions on this subject?

 

[LittleInch]

Post a picture or diagram.

Is the disc circular or not? From description sounds more like 4.4.3 but not enough information. Or why do you need to define it.

 

[ilkerdburhan]

Post a picture or diagram.

Is the disc circular or not? From description sounds more like 4.4.3 but not enough information. Or why do you need to define it.

Thank you,
Disc is circular. I attached a diagram of showing position of disc on full open position. I'm trying to define it because as I see, nominal valve size marking requirements change on body and nameplate according to Table 12 and Table 13 on API6D. Also, I am not sure if It should be specified correctly in technical documents and datasheets.

for 4.4.3 body marking should be DN 100 *50
for 4.4.4 body marking should be DN100R

 

[LittleInch]

I don't think it actually fits any of the descriptions and falls under K 3.2 instead.

The opening in the valve body is full size, but the disc does not, rather strangely, allow for a fully open disc so is a reduced opening full bore valve.

It does not, as far as i can tell, meet either of the requirements of 4.4.3.

I'm though maybe not using the same version of the code.

Can you paste in the whole of section 4.42 to 4.4.4 and state which version you're using as this section has changed quite a bit recently.