3" X 150# API 600 Gate valve Thickness and Port Diameter

[m.wasif]

Hello everyone,

I want to confirm regarding gate valve flange thickness and Port Diameter. I am procuring 3" ×150# Rating gate valve in accordance with API 600. End flanges needs to be in accordance with ASME B16.5. I have noticed that vendors are quoting gate valves having flange thickness of 19.5 mm including raise face, however according to ASME B16.5 the flange thickness of 3" X 150# shall be 24.3mm including raise face.
I want to confirm does the standard Allows thinner flange thickness for 3" × 150# Gate valves? Is valve having 4.8mm lesser flange thickness is acceptable?

Also I have seen many vendors quoting port diameter of 76mm instead of 77.92 mm (as per ASME B36.10 and ASME B16.5).

Please confirm does the standard allows for thinner flanges and lesser port diameter for 3" x 150# Gate valves?

Note: All vendors are quoting like this, that's why I want to confirm that does code allow this variation?

Thanks & Regards,
Wasif

 

[The Obturator]

Good Question.
Current ASME B16.5 (2017) Gives 3" Class 150 Flange Thickness (Tf) of 22.3 + 2mm = 24.3 mm confirming your statement (2mm is the raised face thickness).

ASME B16.5 prior to 2003 edition had total thickness (C) at 23.9 mm. There are notes in the preface of all editions 2003 onwards describing this change. Though I too cannot find or understand why manufacturers of gate valves list a 19.5mm total thickness. I have looked at various drawings and they indeed do that.

I would ask the question to the manufacturer. Note that there is a fixed "L" Length limit that such valve designs have (flange face to flange face), to conform to API-600. At a guess, it may be difficult for established designs to incorporate the new thickness and maintain the length. Whether there is an allowance to do this, I am not sure. Hence the manufacturer needs to be questioned. Maybe these are left over stock?

Port diameter of 76mm for 3" is simply metricated and rounded down for 3". It is the flow Cv value that matters, and in any case, this dimension is effectively a DN Nominal Diameter usually expressed as "80" against the flange size.

So in summary, you need to ask the manufacturer why the flange thickness is so, since as it stands, it is not conforming to spec. Please come back with their comments to share. Thanks.







Per ISO-4126, only the term Safety Valve is used regardless of application or design.

 

[LittleInch]

Look at table 9 (Dimensions of flanged fittings, not table 8 (Dimensions of flanges)

Table 9 min Tf for a 3" class 150 flange is 17.5mm, so add 2mm = 19.5mm





Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[The Obturator]

Thanks for the clarification LittleInch.
"Flanged Fittings" as per table 9 really means integral flanges i guess.


Per ISO-4126, only the term Safety Valve is used regardless of application or design.

 

[m.wasif]

Thanks LittleInch & The Obturator

After reviewing Point# 3 in Notes of Table 8 (ASME B16.5- 2009), the code allows for thinner flanges for size less than 3-1/2". Refers to Table # 9 of Dimensions of Class 150 Flange fittings that shows thinner flange size and port diameter.

Therfore to summarise yes the code allows for that and that's why vendors are quoting according to Table 9 of ASME B16.5.

Thanks all.

Wasif