ASME B16.5 minimum nuts thickness

[Matchess]

Hi

AMSE B16.5 recommend to use heavy hex.
However it is only a reommmendation, is it possible to use hex (smaller nuts) and why ?
What is the minimum nuts characterisics or size ?

 

[TGS4]

What possible reason would you have to go against the "recommendation" of the experts involved in the ASME B16.5 standard? If something were to go wrong (up to and including someone being killed), and you were standing before a judge, could you come up with a rational technical reason that you would go against such a recommendation?

There is no technical reason for that recommendation provided in the Standard, and the Committee will likely not provide you with one. Nevertheless, you are an engineer - so go ahead and figure out if your special case is adequate.

 

[MJCronin]

Yes, ASME B16.5 Flange Standard recommends the use of heavy hex nuts.....for good reason

When heavy hex nuts of the correct material are used, this ensures that the full strength of the stud/bolt is developed. The bolt/stud will fail before the heavy hex nut is stripped.

I disagree with TGS4 when he states "There is no technical reason for that recommendation provided in the Standard"

This is discussed in the Bickford text:

https://books.google.com/books?id=N...ge&q="heavy hex" nuts "full strength"&f=false

http://www.rbwmfg.com/Media/Default/Products/Engineered/Technical Information/HelpfulHints2.pdf

MJCronin
Sr. Process Engineer

 

[TGS4]

MJCronin - I completely agree with your technical justification with using heavy hex nuts. My only point is that this aspect is not called out explicitly in the B16.5 text. But it is indeed mentioned in alternate texts, such as Bickford.

 

[MJCronin]

Matchless.....

Exactly what type of nut design do you want to use with your B16.5 pipe flanges ?

What type of materials do you want to use for both the studs and nuts ?

Are the materials approved by ASME ?

What maximum temperature will your flanges encounter ?

MJCronin
Sr. Process Engineer

 

[Matchess]

I will use ASTM A194 B8M material (stainless steel 316)
The stud and bolt will have ISO threat.
The pipe will be in cryogenic conditions and will never reach realy high temp (max 100 °C).

Sometime with flange valve it is not possible to install Heavy hex, but only Hex (not enough space between valve flange and the valve body).
In this case we are oblige to use Hex. But how to prove that this design is ok ?

On ASTM A194, nut according to Hex, Heavy Hex acc to ASME B18.2.2 or ASME B18.2.4.M and ISO 4033 are also allowed.
with mean that hex is also ok ?
Moreover, ISO 4003 nuts seam lighter than heavy hex (acc ASME).

 

[mk3223]

Sometime with flange valve it is not possible to install Heavy hex, but only Hex (not enough space between valve flange and the valve body).

Just wondered if the flanged valve complied with the Code design?

 

[Matchess]

Yes it is standarde ASME B16.5 fLanges with the valve face to face dimension in line with B16.10

 

[MJCronin]

IMHO, if the dimension from the backside of the flange to the cast valve body is not large enough to place a standard heavy hex nut;

1) The valve is defective and the vendor should be contacted to explain. Are all of his valve like this or just one particular valve ? Does just one stud/bolt not have enough clearance or do ALL inside nuts not have enough clearance.

2) If you cannot get a heavy hex nut in place, how can you check thread engagement ?

3) Why have you not posted pictures ? Show us how the Heavy Hex does not fit...

4) You DO realize that washers are not required (optional) for this type of bolted connection .....Right ?

MJCronin
Sr. Process Engineer