Do pressure vessels Anchor bolts need torquing 3

[extremechanical]

Hi, One of the spec says once pressure vessels are installed on foundation ( Anchor bolts are concrete bound) , nuts have to be torqued to a pre determined value. Specification gives tensioning values based on Anchor bolts dia and Material. Do we have any value in tensioning concrete bound bolts? Does any standard recommends static Equipment Anchor bolts need to be torqued ? If so please refer.

Thanks a lot,

 

[jte]

Well, I'll go out and say the answer to your query is a "definite maybe." Not the response you are looking for but realistic.

Most vessel baseplates / chairs / anchor bolts are not designed to be pretensioned. In this case, "snug" is the operative term. But a very few vessels, typically of the large variety and in heavy wind or seismic areas, are designed with pretensioned anchor bolts. These add a couple bolts (half the bolts plus 2 usually) acting in tension to counter the overturning moment.

My thoughts on the matter: It is difficult enough to get pressure containing flanged joints tensioned properly. To have 49 vessels in a facility with no torque requirements and 1 "special" is asking for the pretensioning to not occur, or to not be maintained. So I'm generally opposed to the notion but open to a one-off argument for a particular case if somebody were to bring one up for my review.

The ASME Post Construction Committee has had a long-term effort to write an article for PCC-2 which would include this issue. It's been stalled out for years primarily because of the pretensioned anchor bolt issue. The possibility exists that the article might make it into the 2018 edition, but I won't be expecting it to happen.

 

[r6155]

Use the spec you mentioned as standard.

Regards
r6155

 

[saplanti]

What your calculation says about the anchor bolting? Is the vessel vertical and skirt supported or horizontal and saddle supported?
I suggest you to read Pressure Vessel Handbook by Paul Buthod for anchor bolt calculation.

 

[r6155]

1)Vertical vessel: A few impacts with an impact wrench or the full effort of an ironworker using an ordinary wrench

2)Horizontal vessel
Fixed saddle: as per 1)
Sliding saddle: hand tight

Regards
r6155

 

[MrPDes]

For tall vessels, fatigue in the hold down bolts due to cyclic wind loading needs to be considered. Pre-tensioning the bolts will reduce this fatigue.

 

[r6155]

MrPDes
In most cases for vertical PV required bolting is defined due to condition of empty PV + wind
When the PV is in service, can we say 99 % of the time, required bolting is less.
Do you understand that fatigue analysis need to be considered during 1% of the time (empty PV +wind)?

Regards
r6155