×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Tightening the anchor bolt's nut

Tightening the anchor bolt's nut

Tightening the anchor bolt's nut

(OP)
Dear experts :)

Is there any standard / code about how many NM or Ft.Lb required when we are tightening the nut of the anchor bolts on the tank ?

Best regards,

Syah

RE: Tightening the anchor bolt's nut

I assume that you have an API-650 style metallic storage tank.

Good information here: http://www.engineersedge.com/civil_engineering/con...

Generally speaking, there is no hard and fast rule for tank anchor bolt torque. " Turn of the nut" method is commonly used.

http://www.civildesignhelp.info/ab.html

Do not torque the tank anchor bolts until the tank has its initial fill of liquid.

More information here: (but its for plastic tanks !)

https://books.google.com/books?id=Go10cKT7vgoC&...

MJCronin
Sr. Process Engineer

RE: Tightening the anchor bolt's nut

(OP)
Thanks MJ Cronin.

RE: Tightening the anchor bolt's nut

API 650 says: "Any anchor bolts shall be uniformly tightened to a snug fit (nuts hand tight in contact with anchor chair top plate plus maximum of 1/8 turn with wrench)... Measures such as peening the threads, or adding locking nuts, or tack welding nuts to chairs, shall be taken to prevent the nuts from backing off the threads."

RE: Tightening the anchor bolt's nut

Before you lock the anchor nuts, RETIGHTEN! Don't know the mechanism, can't get any good guesses from the eng's I've talked to but:
After the first tightening of anchors in concrete, especially cast-in-place anchors, they loosen themselves up. After the vessel/tank has had a few days after being full, per MJCronin post above, go back and Retighten, then lock the nuts [if you wish].

Don't overthink the 'Snug Tight'. For smaller stuff, it is "Full effort of a man on an ordinary [spud] wrench". For bigger stuff [like anchor bolts], it is "A few blows of an impact wrench". Put a wrench on the nut, hit it a couple of times with an ironworker's 'beater' [4# to 8#], keep hitting until the nut stops turning and the hammer just rebounds, and you are done. Rinse and Repeat.

RE: Tightening the anchor bolt's nut

Note that certain high-strength bolts are required to be pre-tensioned to specific levels, not applicable to normal Grade-36 bolts.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources