We track the calls that start with "is this the right spec for…"
Over the last several years, the same handful of standards come up on repeat — A193 B7, F1554, A325, A194 2H, A307, F593. Different projects, different engineers, same underlying questions. Sometimes it's a procurement team reading a drawing for the first time. Sometimes it's an experienced structural engineer who knows exactly what they want but isn't sure if they've specified the right nut grade to go with it.
We kept answering those questions one at a time. Then we wrote them down.
The result is our Specification Library — plain-English breakdowns of the ASTM and SAE standards we stock against, built for the engineer who's diving in cold from a drawing and needs to get oriented fast. Not a replacement for the full standard (we're not reproducing ASTM's dimensional tables), but a quick-reference for the question that actually gets asked: what is this, and when do I use it?
Before you click over, here's a preview of the specs that generate the most confusion — and the quick answers.
A193 and A194: The Pair That Gets Ordered Separately
ASTM A193 is the bolt spec. ASTM A194 is the nut spec. They almost always go together — and they're almost always ordered separately, with one side of the assembly specified on the drawing and the other omitted.
A193 B7 is the most common alloy stud bolt grade: chromium-molybdenum steel, heat-treated, 125 ksi minimum tensile strength. It's the default choice for pressure vessels, flanged piping, and high-temperature service. You'll see it specified on virtually every petrochem, power generation, and refinery job.
A194 2H is its standard nut companion: carbon steel, heat-treated, designed for use with B7 studs in high-pressure and high-temperature service. When a drawing specifies A193 B7 studs without calling out a nut grade, the correct assumption is A194 2H — but it's worth confirming before you order.
The stainless pairing works the same way: A193 B8M studs (316 stainless) pair with A194 8M nuts. Order one without the other and you've created a mixed-assembly problem.
F1554: The Spec That Needs a Grade
ASTM F1554 is the umbrella standard for anchor bolts — the bolts used to anchor structural supports, base plates, sign structures, light poles, and equipment skids to concrete foundations. The standard covers three strength grades: 36, 55, and 105.
The most common mistake we see on anchor bolt drawings is a callout that simply reads "F1554" without specifying the grade. That's underspecified. The three grades have meaningfully different mechanical properties:
- Grade 36 — Plain carbon steel, 36 ksi minimum yield. The light-duty standard: sign posts, light standards, small base plates. Weldable.
- Grade 55 — 55 ksi minimum yield, still weldable, and the common choice for structural base plates in commercial construction. Often dual-certified to A572 Grade 55, but only if you specify supplemental requirement S1 — it's not automatic.
- Grade 105 — Quenched-and-tempered alloy steel, 105 ksi minimum yield. Heavy equipment anchors, transmission structures, any application where the engineer needs the load without increasing the bolt diameter. Not weldable.
When a drawing just says "F1554," we default to Grade 36 — but we'll always call and confirm if the application context suggests otherwise. The load difference between Grade 36 and Grade 105 in a 1-1/4" diameter anchor bolt is not a rounding error.
A325 vs. F3125: The Superseded Standard That Won't Go Away
ASTM A325 is still the most commonly specified structural bolt grade in the field — it shows up on decades of existing drawings, in contractor bids, and in everyday procurement conversations. But A325 was officially withdrawn as a standalone standard in 2016. It's now incorporated into ASTM F3125 as Grade A325.
For practical purposes, if a drawing calls for A325 bolts, you order F3125 Grade A325 — the mechanical requirements are the same. The consolidation also brought A490 (the higher-strength structural bolt) under the F3125 umbrella as Grade A490. So F3125 is the parent spec; A325 and A490 are now grades within it.
Why does this matter? Mostly for documentation. When a job requires certified material test reports or compliance traceability, the cert should reference F3125 — not a superseded standard. If a supplier is still certifying to A325 only, that's worth flagging.
A307 vs. Grade 5: When "General Purpose" Means Two Different Things
These two show up together because they're both used in lower-stress, non-critical applications — and because procurement teams often treat them as interchangeable when they aren't.
ASTM A307 covers carbon steel bolts and threaded rod with a 60 ksi minimum tensile strength. It's the standard for anchor bolts in general construction, flange bolts in low-pressure applications, and anywhere the engineer needs a documented specification but not high-strength performance.
SAE Grade 5 is a medium-carbon steel bolt with a minimum tensile of 120 ksi — significantly stronger. It's the standard machine bolt grade for automotive, industrial machinery, and general mechanical assemblies.
The confusion surfaces when someone asks for "a general-purpose bolt" without a project specification. A307 is the ASTM answer; Grade 5 is the SAE answer. The right choice depends on whether you're building to a structural specification or a mechanical assembly standard. If the drawing doesn't specify, ask the engineer — not the supplier.
What the Library Covers
The California Fastener Specification Library organizes ASTM and SAE standards by category: bolt specs, nut specs, and washer specs. Each entry opens with a plain-English summary of what the standard covers, which grades we stock, and which applications it's typically used in.
Current coverage includes:
Bolts — A193, A307, A320, A449, F593, F1554, F3125 (A325/A490) Nuts — A194, A563, F594 Washers — F436, F844, F959
Each standard includes cross-references to the grades and companion specs it's commonly paired with — so when you look up A193 B7, you're one click from A194 2H.
Not Sure Which Spec You Need? Start Here Instead.
The Spec Library assumes you already have a spec number and need it explained. If you're earlier in the process — application defined, environment known, but no spec on the drawing yet — the Material Spec Builder is the faster starting point.
It asks four questions: what are you fastening, what environment will it be in, what strength range do you need, and whether there are any material constraints (stainless only, DFARS-compliant, specialty alloy acceptable). From those inputs it narrows the field down to the grades that actually fit, with a direct path to a quote. It won't replace an engineer's judgment on a critical connection, but it's useful for getting a short list before picking up the phone.
What It Isn't
Neither tool is a substitute for the full ASTM standard. They don't reproduce dimensional tables, tolerance charts, or test method requirements — that content belongs to the standards bodies. The library and the spec builder are for orientation and quick reference, not for design-level specification work.
If you have a question that neither resource answers, call our engineering team. The phone call is faster.
Browse the Specification Library →
Open the Material Spec Builder →
California Fastener stocks and supplies fasteners to ASTM, SAE, and ASME specifications for construction, infrastructure, power generation, oil and gas, and industrial applications. Full material traceability and certified test reports on every order. Request a quote →
