ASTM A325
ASTM A325
(OP)
I AM TRYING TO FIND A REFERENCE CHART FOR THE TORQUE SETTINGS REQUIRED TO INDUCE A TENSILE STRESS OF 70% OF YIELD STRENGTH OF A325 BOLTS. THE STRESS NEEDS TO BE IN kips
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RE: ASTM A325
Thread288-21503
Also, you can perform an ADVANCED SEARCH using keywords like torque and fastener for more information.
RE: ASTM A325
As the condition of the individual bolt/nut/washer set changes the torque required to acheve the required tension changes. The only way to determine that value for the lot of A325 bolts is to use a Skidmore/Wilhelm, and take the average torque developed to meet the required tension.
RE: ASTM A325
Thanks for the reference Rjeffery, this is definitely a “keeper”. I always enjoy it when I find (in this case, more like “am handed”) a “non-aerospace” document that I can use to shame less “enlightened” “aerospace” co-workers with, as in: “See, not even the civil engineering guys would do that..."
RE: ASTM A325
1) use a standard value from a table for noncritical applications (example: M6 screw to attach wiring clips to vehicle structure)
2) use calculation for a non-safety-critical, but structural application (example: M10 screw to attach powertrain mounts to vehicle structure)
3) use testing for safety-critical applications (example: M12 nut to attach steering arm to upright)
Automotive companies have spent considerable time developing materials and coatings specifications for fasteners. For example, friction coefficient is tightly controlled, so using calculations like those from VDI 2230 Systematic Calculation of Bolted Joints (see the thread posted by TVP above) can be used with confidence.
I concur with previous comments that tables and calculations cannot be used for critical attachments if there is no knowledge about the important joint variables. However, calculations are very accurate is the variables are known. These include:
joint geometry
joint material properties
fastener geometry
fastener material properties
friction coefficients
input forces
input torque variation
RE: ASTM A325
The last job I was sent to inspect has me face to face with the iron worker foreman who told me that I didn't need to look at any thing because he had personaly 'torqued' all the 3/4 inch bolts to 490 ft/lbs 'just like it said on the bolt head...'
OBTW turn of the nut was specified and there was a pile of sheared bolts in the dumpster!
I also found 35 shoulder bound bolts!
Torque should never be specified for buildings.
I can see the need for uniform tension on a head or oil pan in the automotive field and that is achieved by specifing a standard torque value. But most mechanics (marine, aerospace, rail or automotive) are fastidious.
:)
RE: ASTM A325
RE: ASTM A325
RE: ASTM A325
Torque is not a reliable means of achieving tension load in bolt assemblies. According to the RCSC, you can get as much as +/-40% variation from one bolt assembly to the next using torque as your installation criterion. See if you can get a copy of the Research Council on Structural Connections manual - Specification for Structural Joints using ASTM A325 or A490 Bolts - www.boltcouncil.org. This will give you much useful information. Check out load indicating washers or ultrasonics, depending on what you want to spend.
RE: ASTM A325
The direct link to that document (which was referenced by Rjeffery in this thread) is included in my Dec 9, 2002 post above ...