Attribute Schema Library
Attribute schemafastener distribution

Hex Bolts Attributes

A hex bolt is an externally threaded fastener with a six-sided head, driven by a wrench or socket and normally tightened against a nut. Distributors sell it as a grid: diameter and pitch, length, grade, finish. The grid is the category — one 1/2"-13 line runs to several hundred SKUs before a second grade is added.

Buyers are MRO purchasers replacing a known part, contractors and fabricators buying to a drawing callout, and OEM supply chains buying to a print. The first two search; the third filters. All three reject a part on a spec the catalog never published.

The data is hard for three reasons. Three dimensional standards — ASME B18.2.1, ISO 4014, DIN 931 — disagree on head dimensions at specific sizes, so the standard has to be its own field. The strength callouts drift: ASTM withdrew A325 and A490 in 2016 and re-issued them as grades under F3125, and both strings are live in the market. And the numbers buyers actually need — proof load, thread length, coating spec — live in mill certs and datasheet PDFs, not in the supplier's price file.

Core

Every SKU needs these. Without them the record is not a product, it is a row.

Product Type
enum
Hex Cap Screw

Hex bolts and hex cap screws are separate products under ASME B18.2.1. Cap screws hold tighter body and head tolerances and carry a washer face.

Thread Size
enum
1/2"-13

The first filter every buyer touches. Nominal diameter and pitch together; drives mating nut, tap drill and socket selection.

Thread Series
enum
Coarse (UNC)

Coarse and fine share a diameter but not a pitch. UNF gives finer preload control; UNC tolerates thread damage and galvanizing better.

Length (Under Head)
number · in
2-1/2 in

Measured under the bearing surface on hex heads. Decides whether the bolt crosses the joint and still leaves full nut engagement.

Head Style
enum
Heavy Hex

Heavy hex heads are wider across flats than standard hex at the same diameter. Structural connections call heavy hex out specifically.

Material
enum
Medium Carbon Steel, Quenched and Tempered

Sets corrosion behavior and the strength ceiling. 18-8 cannot be heat treated to Grade 5 strength; silicon bronze is marine, not structural.

Grade / Property Class
enum
SAE J429 Grade 5

The strength callout. Inch grades come from SAE J429 or ASTM; metric classes from ISO 898-1. The two systems do not cross-substitute.

Finish / Coating
enum
Hot-Dip Galvanized

Drives corrosion life and thread fit. Hot-dip zinc is far thicker than electroplate and needs an overtapped nut to assemble.

Thread Coverage
enum
Partially Threaded

Fully threaded bolts develop no grip in a shear joint. Structural details routinely prohibit threads in the shear plane.

Manufacturer Part Number
identifier
BBI 21100

Join key to the supplier datasheet, mill cert and replenishment record. Fastener MPNs collide across brands, so brand must travel with it.

Differentiating

What buyers actually compare on. This is where catalogs win or lose the filter.

Thread Length
number · in
1-1/4 in

With overall length this gives grip. A buyer sizing a 1 in grip needs unthreaded body length, not total length.

Width Across Flats
number · in
3/4 in

The wrench size. Also the field separating DIN 931 from ISO 4014 at M10, M12, M14 and M22, and heavy hex from standard hex.

Minimum Tensile Strength
number · psi
120,000 psi

The number buyers compare grades on. Grade 5 is 120,000 psi, Grade 8 is 150,000 psi, and Class 8.8 is not Grade 8.

Minimum Proof Load Stress
number · psi
85,000 psi

What the joint is torqued against — preload targets are set as a percentage of proof load, not of tensile.

Compliance & identifiers

Standards, regulatory data, and the identifiers channels reject you for missing.

Dimensional Standard
enum
ASME B18.2.1

ASME B18.2.1, ISO 4014 and DIN 931 are not interchangeable. The standard, not the size, decides head dimensions.

Coating Specification
enum
ASTM F2329

"Galvanized" is three processes. F2329 hot-dip, B695 mechanical and F1941 electroplate differ in thickness and cannot be mixed in a lot.

Country of Origin
enum
Taiwan

Drives tariff classification, and federal, DOT and transit jobs restrict origin. Buyers filter on it before they filter on price.

GTIN / UPC
identifier
00081939211004

Required to list on marketplaces and to sync through GDSN. Fastener SKUs proliferate by pack size and each pack needs its own GTIN.

The fields that aren't in the schema at all

What most hex bolts catalogs are missing.

The table above is the schema most catalogs already have. These are the attributes that usually aren't in it — each one surfaced by a signal from the live market rather than by an audit of what's already there. This is what Anglera's Schema Foundry does on a real catalog, in this category.

Search signal
+ Thread Length / Grip Length

Buyers ask "how much unthreaded body?" on RFQs and phone calls constantly. Most catalogs publish overall length only and leave thread length to the ASME B18.2.1 formula in a PDF appendix.

Buyer picks a length that puts threads in the shear plane, or orders fully threaded where grip was required. The part gets installed, not returned.

Supplier signal
+ Coating Specification (Process + Standard)

Catalogs carry "Galvanized" as a finish value with no process behind it. Supplier datasheets name F2329, B695 or F1941 explicitly; the distinction disappears at the catalog layer.

Hot-dip bolt shipped against a mechanically galvanized nut. Threads bind on install, and F3125 assembly lots reject mixed processes outright.

Search signal
+ Domestic Melt / DFARS Status

Buyers on federal, DOT and transit work open with "is it domestic?" before asking price. Few distributor filter rails expose a melt-origin field at all — it lives only in the mill cert.

The SKU never reaches the buyer's shortlist. The RFQ goes to a specialist who publishes the field, and the quote is never requested.

Competitor signal
+ Dimensional Standard

Specialist metric distributors expose a DIN/ISO filter. General MRO catalogs list "M12 x 60" with no standard named, though width across flats differs at M10, M12, M14 and M22.

Buyer receives a bolt their 19 mm socket does not fit, or a head that fouls an adjacent boss. Return, plus a line-down call.

Competitor signal
+ Product Type (Bolt vs Cap Screw)

Category nodes read "Hex Cap Screws and Hex Bolts" as one heading, so both parts share a spec block. ASME B18.2.1 treats them as separate products with different tolerances.

Buyer specifying a cap screw for a close-tolerance hole receives a hex bolt with wider body tolerance. Fit problem at assembly, not at receiving.

How Schema Foundry finds these

Messy in, governed out.

The same value, spelled every way fastener distribution suppliers spell it. A filter only works once they agree.

Finish / Coating
HDGHot Dip GalvHOT-DIPPED GALVANISEDGalvHot Dipped Zinc
Hot-Dip Galvanized (ASTM F2329)

Hot-dip zinc runs far thicker than electroplate. Collapsing it into a generic "Zinc" value hides that the nut must be overtapped.

Grade / Property Class
G8Gr. 8Grade8SAE 88GR8
SAE J429 Grade 8

A bare "8" collides with metric Class 8.8. Grade 8 is 150,000 psi tensile; Class 8.8 is 120,000 psi. Not substitutes.

Thread Size (Metric)
M12x1.75M12 X 1.75M12-1,7512M x 1.75M12 (1.75)
M12-1.75

Comma decimals arrive from EU suppliers. Unnormalized, each spelling becomes its own facet value and the M12 filter splinters.

Material
18-8SS304304 SSA218/8 Stainless
Stainless Steel, 18-8

18-8 is a family covering 302, 303 and 304; A2 is the ISO 3506 equivalent. Buyers who need 316 specifically must not match these.

What buyers ask

Every one of these should be answerable from the attributes above. If it isn't, that's a gap.

  • Is this a hex bolt or a hex cap screw? I need the tighter head and body tolerance.
  • How much unthreaded body does it have? I need 1 inch of grip in the joint.
  • Will a standard nut run onto this, or is it hot-dip galvanized and needs overtapping?
  • What's the proof load? I'm torquing to 75% of it.
  • Is this A325 or F3125 Grade A325 — will my inspector take it?
  • Does your M12 take an 18 mm or a 19 mm socket? Is it DIN 931 or ISO 4014?
  • Is the steel melted and manufactured in the US? This is going on a federal job.
  • Is the head grade-marked? Unmarked bolts get rejected at inspection.

What channels require

The same SKU, different mandatory fields per destination.

Distributor faceted catalog (own site)
Thread SizeThread SeriesLength (Under Head)Grade / Property ClassFinish / CoatingThread Coverage
Amazon Business
GTIN / UPCManufacturer Part NumberThread SizeLength (Under Head)MaterialCountry of Origin
Punchout / ERP catalog (cXML, CIF)
Manufacturer Part NumberUNSPSC codeUnit of MeasureThread SizeGrade / Property ClassCountry of Origin
GDSN / 1WorldSync
GTIN / UPCBrand Owner GLNNet ContentCountry of OriginManufacturer Part Number

Hex Bolts data, in practice

Do I need separate records for hex bolts and hex cap screws?

Yes. ASME B18.2.1 covers both, but they are different products. Hex cap screws hold tighter tolerances on body diameter, head height and width across flats, and carry a washer face under the head; hex bolts do not. A designer who specified a cap screw for a close-fit hole will not accept a hex bolt at the same nominal size and grade. Merchandising them under one category node is fine — most distributors do. Collapsing them into one spec block is not: the tolerance and washer-face differences have to be filterable, which means Product Type must be a governed attribute rather than a word buried in the description.

Should I list A325 or F3125 Grade A325?

Both. ASTM withdrew A325 and A490 as standalone specifications in 2016 and folded them into ASTM F3125, where they survive as grade designations. But drawings issued before the change — and plenty issued after — still call out "A325", and that is what buyers type into search. The governed value should be "ASTM F3125 Grade A325", with "A325" carried as a synonym so search resolves it. Same for A490, F1852 and F2280. Dropping the legacy string in the name of correctness costs you the traffic; publishing only the legacy string costs you the inspector.

Why store thread length if the ASME formula already gives it?

Because the formula yields a minimum, not a value. ASME B18.2.1 derives nominal thread length from diameter and length, and grip gaging length follows as LG = L − LT — but actual thread length can run longer, and it varies by manufacturer, by standard, and by whether the part is fully threaded. A buyer sizing grip for a shear joint needs the number for the part in the box, not the number the formula predicts. Storing it also makes "partially threaded" mean something: without thread length, that enum tells a buyer only what the bolt is not.

Which finish values actually need to be governed?

All of them, because finish here is two fields pretending to be one: appearance and process. "Zinc" can mean an electroplated coating a few microns thick per ASTM F1941, or a mechanically deposited one per B695. "Galvanized" usually means hot-dip per F2329 but gets applied to both. The thicknesses are not close, and they decide whether a standard nut will run on or whether it must be overtapped. F3125 further restricts a fastener assembly to one process per lot. Split the field: Finish carries the appearance value buyers filter on, Coating Specification carries the standard the mill certified to.

More fastener distribution schemas

Blind RivetsConcrete AnchorsHex NutsSocket Head Cap ScrewsThreaded RodWashers

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