All thread roods

[pantro1977]

Can two flages be connected using all thread rods instead of machine bolts? Contractor bought 10' long pieces of all thread rods and they cut them on site to use them as bolts to connect flanges and also to connect butterfly valves to flnages. Our specs don't mention anything about the allowable bolts and I want to know what the industry standard is.

See Pictures!!

 

[msquared48]

If the contractor used something other than what was specified, it is up to him to prove to you that what was provided is as good as or better than what you specified.

He needs to look up the information and give it to you. If he cannot find it, have him adhere to the spec at his cost.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[MintJulep]

Can they? Yes.

Should they? Maybe not. How strong do the connections need to be? Is all thread strong enough?

What is the industry standard? What industry are you in? What country are you in?

 

[JJPellin]

You would probably get a better response in a piping forum. However, I will comment on my experience. I work in a large oil refinery. Our piping specifications are quite specific that piping flanges should be connected using studs, not bolts. The use of bolts would be considered a deviation from specifications and would require additional approval. Studs are much, much more common as the preferred fastener in flanged joints in piping.

With that said, the strength of these joints depends on the grade of stud that was used and the method of tightening it. If the specification called for Grade 8 bolts, then B-7 studs would normally be considered to be equivalent. But, since the contractor cut up sections of all-thread rather than buying pre-cut studs which likely would have been stamped on the ends, it may be difficult to verify that the stud grade is correct.

If you are responsible for the integrity of these joints, they you need to be sure that the fasteners are appropriate. But, there is no fundamental reason that I am aware of that studs would be inferior to bolts as long as the strength was the same or better. In fact, studs are likely to be superior because each nut can turn independently. As long as they are tightened correctly, then you are less likely to have a problem with a stud. I prefer studs and our specifications require them.


Johnny Pellin

 

[SnTMan]

ASME Sec VIII, Div 1 specifically requires that studs be full-threaded, or that unthreaded portions be reduced to the root diameter.

I have had Fastenal supply 3 ft. lengths of B7, so marked on one end.

pantro1977, I agree it is your contractor's responsibilty to PROVE what he has supplied. If he cut a spec stud material into pieces there will be no markings, no proof.

Regards,

Mike

 

[jte]

Agree with the comments in the above posts in general. In looking at the photo, however, it seems clear that this is a relatively low pressure expansion joint which is being "bolted" to probably CL-150 flanges, presumably 18" nominal. Just eyeballing the relative thickness of the flanges, and noting that the expansion joint side "flange" seems to be a split ring (zoom in on the right hand side flange right at the 18" label), I'd say that the "flange" is made of 1/4" plate.

Rotation of the flange is a non-issue. It will rotate like crazy. But in this case, that's probably ok. While I would never specify allthread as a flange bolting material for typical pipe flanges, these rings are neither what I would consider flanges nor likely to be built to any flange standard. Is the material of the allthread identified?

If it passes hydrotest, and the fabricator had no spec in his PO saying that he could not do this, it's probably legal and it'll probably work just fine.

jt

 

[unclesyd]

You find that bolts are used mainly in lines that carry things other than hydrocarbons or chemicals. There are tables for standard length studs for every Class. Most suppliers will stock studs made to the tables or will custom cut all thread to your specified length. The majority of stud bolts (studs) are cut from all thread of the proper alloy. The all thread rod can either be rolled or single point cut. The studs are cut to length with a band saw and fed into a machine that chamfers each end and stamps the stud accordingly, or they are cut in machine that does all of the above in one pass. Studs that are rolled individually like bolts are available in all alloys. This is especially true with the larger sizes and higher alloy materials.