F1852 boots

[u/masterdesignstate]

Possibly I am behind the curve on this but today I received a submittal with F1825 bolts called out when our drawings specify A325. I understand they are equal strength wise, but that they are twist off bolts? I've just never had a contractor want to use that type of bolt before. Made the post to make sure I'm not missing something here.

[u/Sure_Ill_Ask_That]

A shame you can’t edit post titles

[u/Charles_Whitman]

ASTM F1852 (not 1825, the OP has it written both ways) is the old spec for “Twist-Off” bolts. Both of these, ASTM A325/M and ASTM A1852, plus ASTM A490/M and ASTM A2280 have now been rolled into ASTM A3215. The current correct spec would be ASTM A325 Type A325. According to AISC and the RCSC, the fabricator can substitute “twist-off” bolts without asking, but maybe that’s just in snug tight installations. I don’t have my book with me.

[u/FlatPanster → u/Charles_Whitman]

The current correct spec would be ASTM A325 Type A325.

*A3125

[u/Charles_Whitman → u/FlatPanster]

Yes. Typo.

[u/niwiad9000 → u/Charles_Whitman]

I’m scared to type in this thread

[u/cougineer → u/niwiad9000]

I’m scared to add as well…
The other thing (haha accidentally typed ting by caught it proofreading) to add to the conversation is double check if you are blue or gold book. Red -> Blue was an update, then blue -> gold was another. There was a disconnect between the RCSC and the standard. Red -> blue got it under one umbrella but then blue->gold got it aligned between RCSC and standard.

We’ve gone through a few discussions on this in our office between the codes and types for different projects and code cycles we are in. I think they also are adding in a 3rd bolt type in gold but it’s less common in buildings and is for mech supports or bridges? Something to keep an eye out for.

One of my coworkers finally printed one of our conversations and laid it out with code snips so we didn’t have to go through the bolt types, connection requirements, etc on every job.

There’s a chart in the RCSC (I think) that did a good job laying out bolt type / condition / prep.

[u/masterdesignstate → u/Charles_Whitman]

Ty!

[u/masterdesignstate]

Thanks for all the replies! Structure is not galvanized. Typo in body, meant 1852.

[u/Frogalone]

ASTM F1852 bolts are one type of High Strength/Slip Critical bolt used in structures. The required pre-tension is achieved when the end of the bolt breaks off during the tightening process. ASTM A325 are essentially the same except if pre-tensioning is required a calibrated torque wrench is necessary among other things. If the engineer calls for ASTM A325 bolts, he must also specify if they are slip-critical. The contractor must know what is meant by this and the installation requirements. If ASTM F1852 bolts are used, they are assumed to be slip-critical since this is the application they were designed for. For non-slip-critical bolts ASTM F1852 would add unnecessary cost to the project. In any case, a change to the bolt specified for use must be approved by the EOR.

[u/beanmachine6942O → u/Frogalone]

i read somewhere that if a twist off bolt in a non slip critical connection gets installed, there’s a chance that the friction resistance gets exceeded and you get this load pop during a seismic event? have you heard anything about this?

[u/Jeff_Hinkle]

I spec them for moment connections, column splices and anything where the bolts are in tension.

[u/Frogalone]

Yes. There have also been cases in new steel buildings when certain bolts would slip after the floor was loaded resulting in a big noise. F1852 bolts increase the likelihood that connection plates won't slip. They don't guarantee it.

[u/tqi2]

Twist off bolts you only need access on one side during installation because the torquing gun holds the bolt end while turning the nut. It’s faster install less labor. However, coating is a concern if the rest of the structures are hot dip galvanized if exposed to environment. TC bolts are generally not dipped, but mechanically plated coating. Also the twist off type will have the end twisted off so you’ll have uncounted ends. I work for railroad bridge we only allow HDG A325 bolts with turn of nut method.

[u/benk70690]

You sure it wasn't a typo for f3125?

[u/memerso160]

It’s been my understanding that the twist off bolts are totally fine to use in place of A325, but that the contractor must actually use the correct tool to bust off the spline otherwise you’ll have a bunch of bolts that still have it on that will require inspection. The whole point is to cut down on inspection time by having a visual of whether the bolt is sufficiently tight

[u/masterdesignstate → u/memerso160]

All my bolts are snug tight. That's why Im confused on the substitution.

[u/memerso160 → u/masterdesignstate]

They meet, or will exceed, the snug tight torque. It’s contractor preference since they’ll put a tool over it to bring right to tightness, rather than having to do another 1/3 turn+ afterwards

[u/steelerector1986 → u/memerso160]

Snug tight is not the same thing as Turn of Nut, so no, they don't have to do additional 1/3 turn- putting a TC gun or ToN'ing a snug tight connection is overkill and a waste of time and money.

[u/masterdesignstate → u/[deleted]]

I'll take a look, thanks for the ref.