Process Equipment Anchor Bolting Torque

[LPC1]

Hello,

I want to know which is the torque value to be applied on the base anchor bolts of pressure vessels, process columns and stacks.

Can I simply use the torque values determined for bolts considering bolt diameter and material?

Some say the correct practice is tightening the nut by hand until it locks, then tighten it a quarter of round by tool (nut wrench), put on it a lock-nut and tight it by tool again. Is it correct?

Isn't this harmful to the concrete and grouting?

Is there any standard mention about anchor bolting torquing?

Thanks!

LPC1

 

[desertfox]

Hi

You need to consider the pullout force of the bolt from the concrete.
I given a link to a typical Hilti fastener with a given grouting/concrete system, if you read through it, it will give you some idea for what you are trying to do

http://www.hilti.co.uk/fstore/holuk/techlib/docs/HVU - HAS_1.pdf

 

[fegenbush]

If the anchorage does not require a specific preload, snug tight should be acceptable. Snug tight is defined as "...the full effort of a worker with an ordinary spud wrench..." in the AISC Steel Construction Manual.

 

[dhengr]

It would seem that the designers and manufacturers of the various pieces of equipment might have something to say on this matter. It would be a critical/significant consideration in their design, as regards lateral loads, etc. Do their specs. and drawings give you any direction on this? Why don’t you ask them, how they want this done? This is not something which would be covered by a simple rule-of-thumb in every case.

 

[TGS4]

dhengr has it exactly right. Furthermore, there may be considerations for the thermal expansion of the anchored elements. Long horizontal vessels could grow significant distances (inches or more), while vertical vessels' skirt bottoms could be designed to grow radially ~1/2in. You REALLY don't want to be torquing up anchor bolts that need to be "loose".

 

[zcp]

Assuming they are installed anchors (Hilti, etc.)....Determine the manufacturer of the anchors (if possible), then check their installation guides which will give a maximum installation torque.

For instance, for a 3/4" dia HIT-HY 150 MAX with threaded rod.... Tmax = 100 ft-lbs.

http://www.us.hilti.com/fstore/holus/techlib/docs/HY150 MAX IFUs.pdf

Note that they will lower this at close edge distances (see the tech guide)

ZCP

http://www.phoenix-engineer.com

 

[prichmon]

Shouldn't the solution start at the equipment manu. requirements, then to the foundation material and finally fasteners for specs looking at the system as a whole?

Our facility typically has 20-55 year old attachment materials which typically requires NEW foundations or increasing the number, size or type of fastener to secure properly. 1950's concrete and steel in my experience is typically 1/2-2/3 the strength of material today. Possibly 2 different diameter studs could be used?

Rich