These bolts are identical with regard to strength and chemistry. There are very minor differences in the hardness requirements, but the proof load, tensile, and yield strength requirements are the same. From a manufacturing standpoint, we make these bolts using the same raw material and the same heat treating and production methods. Our strength by grade chart gives a detailed comparison.
The difference between these two specifications (A325 and A449) is the diameter range, configuration, and application. A325 bolts are heavy hex head bolts ONLY, and are designed for structural steel connections. They range in diameter from ½” – 1-1/2” inclusive. Due to their application, an A325 structural bolt has a shorter thread length than a typical heavy hex bolt. If you need a bolt with longer threads, ASTM A449 should be used.
ASTM A449 bolts range in diameter from ¼” – 3” inclusive and are far more flexible in their configuration. In other words, A449 bolts can be a headed bolt, a straight rod with threads, or a bend bolt such as a right angle bend foundation bolt.
With regard to availability, A325 bolts are mass produced and far more common in the marketplace than A449 bolts. Therefore, A325 bolts would be immediately available and considerably less expensive than A449 bolts, unless the bolts you are dealing with are exceedingly long in length. Since the thread length on A325 bolts is very short you should make sure they will be adequate for your application. ASTM suggests using A449 in lieu of A325 when a nonstandard thread length is needed. Here is an excerpt from the A325 specification:
This specification is applicable to heavy hex structural bolts only. For bolts of other configurations and thread lengths with similar mechanical properties, see Specification A 449.
For example, a 1” diameter A325 bolt that exists in the marketplace will have 1-3/4” of thread. There is a supplemental requirement in the A325 specification for fully threaded A325-T bolts that are 4 X diameter in length or shorter. There are often 1” diameter fully threaded A325’s that are readily available but they are no longer than 4” in length.
Portland Bolt’s position regarding ASTM specifications are that they are simply guidelines. They provide a buyer with a reasonable expectation as to the product they will receive if they order it to an ASTM specification. However, if the buyer and seller agree to change any portions of the specification, that is acceptable as long as the change is clear and agreed upon by both parties. Therefore, we frequently manufacture A325 bolts with longer thread lengths than “standard”. Since 1” diameter A325 bolts wouldn’t exist “on the shelf” with that nonstandard thread length anyhow (2-3/8”), it would make more sense to spec the bolt to A449 since it would be the proper spec to use and the bolts would need to be manufactured special regardless of which specification you choose.
Good article and could solve my problem.
I stacked a Rohn tower with 1 ” A325 bolts but I have three area of interference where the head of the bolts can’t pass throught the flange (either up or down) because of a welded brace and bracket. All on the 20′ level, all on each of the three flanges. A total of 3 bolts out of 24 (8 on each flange.
We used a B7 all thread but it is not accepted by the inspector because B-7 has a different application than A325..
Is the A449 all thread equal or greater than A325? Please advise.
@Tim- A449 is a rough equivalent to A325, but the issue is more the difference in performance between threaded rods and headed bolts. In some cases the substitution might be acceptable, and in some it may not be. https://www.portlandbolt.com/technical/faqs/substituting-a-rod-for-a-headed-anchor-bolt/
We are a steel fabricator and are active in bridge fabrication and installation.
The guardrail anchor bolts (rods) are always called of as ASTM A449, and are very difficult and expensive to get, and with long lead times.
B7 threaded rod is readily available and reasonably priced. Is there any reason why B7’s cannot be used in lieu of A449s?
Leo
@Leo- Many times A193 B7 is very similar in chemisty and mechanicals to the requirements of A449, however there are some allowable differences, so care must be taken to make sure that the B7 you use has the desired properties – in some cases the B7 can wildly exceed the A449 maximums. If there are significant differences, the project engineer would need to approve the substitution.
Regarding the comment by Adam stating:
“It is important to note that ASTM A449 bolts are not permitted per AISC standards except for diameters over 1.5″ and in non-slip critical connections.”
I don’t see anywhere in the AISC specification where use of A449 is not permitted.
Dears
Please send us the price of A 449 3” Anchor bolt galvanized for Iraq Basra total quantity = 66 pieces, and let us to know how you can send them to Iraq. Thank you
@Eng.Osama – One of our estimators will contact you shortly to get more details about this.
Design drawing calls for A325 M20x120 Full Threaded bolt. This is out of the box of ASTM Specification with regards to the threading requirements. Special fabrication is not practical since we are only requiring 24 pcs. for the project.
Design team already confirmed that connection was designed as BEARING TYPE and that only SNUG-TIGHTENING is required upon installation. Can we replace it with A449? Eventhough it is clearly mentioned in ASTM A325 that A449 is the replacement material, are we not violating the provision in AISC-360M Section J3.1 with regards to the substitution of A325 with A449?
@Marlon,
I am not intimately familiar with AISC-360, so I do not know how it is worded in regards to bolt substitution. You are correct that an M20 x 120 full threaded A325 is outside the allowable parameters of A325, so that puts you in a quandary. My opinion is that if your design team has given the OK to allow an A449 bolt in place of the A325, that should be sufficient. The engineer of record, if he/she is not on the design team, should also be consulted. ASTM and AISC are guidelines, there will always be circumstances that require adaptation.