All-Thread Rod Grades: What A307, F1554, and B7 Actually Mean

“What grade rod do I need?” comes up on almost every job that uses all-thread, and the honest answer is: it depends on the load and what your engineer or spec calls for. But before that, there’s a more basic mix-up worth clearing up.

A36 is a steel grade, not a rod spec

You’ll sometimes hear all-thread rod called “A36 rod.” A36 is a real ASTM specification, but it covers structural steel plate and shapes (I-beams, angle, flat bar), not threaded fasteners. There’s no product called “ASTM A36 threaded rod” you can actually order to spec. If a job calls for “A36 rod,” what’s almost always meant is a general-purpose, mild-steel threaded rod, ordered correctly by its actual fastener specification:

• ASTM A307, Grade A, the standard, general-purpose threaded rod grade, and almost certainly what’s meant when someone says “A36 rod.”
• ASTM A307, Grade B, similar strength, lower carbon content, more common in piping/flange applications.
• ASTM F1554, Grade 36, a rod spec built specifically for anchor-bolt and structural anchoring use, with a guaranteed minimum yield strength (36 ksi) that A307 doesn’t specify. Worth asking for by name when the application is structural anchoring rather than general hanging/support.

Higher-strength grades

• ASTM F1554, Grade 55 and Grade 105, higher-strength anchor rod grades, used where loads exceed what Grade 36 or A307 can carry.
• ASTM A193, Grade B7, a chrome-moly alloy rod grade used in high-temperature and high-pressure applications (pressure vessels, flanges, some structural connections). Notably stronger than A307 or F1554 Grade 36.
• ASTM A193, Grade B8 / B8M, stainless steel rod grades (B8 = 304 stainless, B8M = 316 stainless), chosen for corrosion resistance rather than extra strength.

Why this matters

Substituting a lower grade than specified is a real safety issue on load-bearing hanger and support work, not a paperwork technicality, a mismatched grade can mean a rod that yields under a load it was assumed to carry. If your project spec calls out a grade, order to that grade specifically, don’t assume “all-thread is all-thread.”

Quick reference

Grade	Typical use	Relative strength
A307 Grade A/B	General-purpose hanging, support, light anchoring	Standard
F1554 Grade 36	Structural anchor bolts	Standard, guaranteed yield
F1554 Grade 55 / 105	Higher-load anchoring	Higher
A193 B7	High-temp/pressure, structural connections	High
A193 B8 / B8M	Corrosion resistance (304 / 316 stainless)	Standard, corrosion-rated