Toruque of bolt mentioned instead of snug-tigh 4

[patelam]

The vendor drawing specifies torque instead of bolts to be snug tightened in steel connection. The vendor is from European countries. Does anyone know if any European countries defines the torque instead of snug-tightening the bolts?

 

[LittleInch]

Better to have some sort of an number rather than some vague description no?

"Snug tight" can mean many things to different people.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[XL83NL]

Whats the scope/subject, and design code? Is this for frames? If its subject to CE-markingfor CPR 305/2011 (EN 1090) there are rules that determine this.


Huub
- You never get what you expect, you only get what you inspect.

 

[LittleInch]

Learn something new every day here....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[dik]

[quote="Snug tight" can mean many things to different people.][/quote]

With most steel codes and ironworkers, it has a specific meaning.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

"You never get what you expect, you only get what you inspect review."

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[ctopher]

If we had automotive/structural/aerospace/etc dwgs indicating 'snug tight', we would have catastrophe's every day.
A torque value is needed.

Chris, CSWP
SolidWorks
ctophers home

 

[LittleInch]

With most steel codes and ironworkers, it has a specific meaning.

Can you give a link or description please. Is there a torque value?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[dauwerda]

Can you give a link or description please. Is there a torque value?

AISC (Steel Construction Manual) uses the RCSC for structural bolts. The RCSC can be found here:

https://www.aisc.org/products/publi...structural-joints-using-high-strength-bolts2/

The RCSC is very specific in NOT assigning torque values because of all of the variables that can effect it in typical field construction.

Snug tight is defined as follows in the RCSC:

Snug-Tight Condition. The joint condition in which the plies have been brought into firm
contact and each bolting assembly has at least the tightness attained with either a few
impacts of an impact wrench, resistance to a suitable non-impacting wrench, or the full
effort of an ironworker using an ordinary spud wrench.

For many structural joints, snug tight is all that is needed, but if it is slip critical or subject to load reversals (or a few other conditions) then it must also be pretensioned. Pretensioning can only begin after the joint is brought to snug tight, then there are a few different methods allowed for pretensioning: turn-of-nut, DTI's, calibrated torque wrench, etc. For the calibrated torque wrench method one must determine the torque required using a skidmore each day. Here is what the RCSC requires:

8.2.2. Calibrated Wrench Method Pretensioning
After the snug-tightening operation has been performed, the installation torque
determined in the pre-installation verification of the bolting assembly (Section
7.2.2) shall be applied by turning the nuts (not the bolt heads) in the joint, progressing
systematically from the most rigid part of the joint in a manner that will
minimize relaxation of previously pretensioned bolting assemblies. It is prohibited
to use this method by turning the bolt head. Torque values determined from tables
or from equations that claim to relate torque to pretension without verification shall
not be used.

(underline emphasis by me)

I understand that this is vastly different than other industries that do specify torque values, but this is the code/standard in the structural world (at least in North America).

 

[patelam]

@LittleInch

I using M12x40 A2/A4-70 bolt to fasten a two SS channels (SS sheet sandwiched between two channels), with washer broad A2/A4 HV200 and two nuts M12 A2/A4-70. The first mounting nut is torqued 8Nm and second (jam) nut is torqued 48Nm.

I want to find out if the torques applied to both the nuts will pretension the bolt or the bolt will remain in snug-tight situation.

 

[Tmoose]

"The first mounting nut is torqued 8Nm and second (jam) nut is torqued 48Nm.
I want to find out if the torques applied to both the nuts will pretension the bolt or the bolt will remain in snug-tight situation."

Is The 8 Nm being considered "snug tight" ?

I'd refer to the navsea and NASA discussions about jam nuts.

 

[Tmoose]

I'd refer to the navsea and NASA discussions about jam nuts.

 

[patelam]

@Tmoose. Yes, it is meant to be a snug tight.