ISO 9001:2015IBR ApprovedEstablished 1971Full Material Traceability
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Square Head Bolts & Square Nuts — OEM manufacturer, Teshi Group

OEM manufacturer ASME B18.2.1 · ASME B18.2.2 · DIN 557

Square Head Bolts & Square Nuts — ASME B18.2.1 / B18.2.2

Square head bolts and square nuts are four-sided fasteners used where a large bearing face and a strong spanner grip are needed. Teshi Group manufactures square bolts to ASME B18.2.1 and square and heavy square nuts to ASME B18.2.2 and DIN 557.

Also called: square bolts, square head bolts, square nuts, heavy square nuts, DIN 557 nuts

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What are Square Head Bolts & Square Nuts?

A square head bolt has a four-sided head; a square nut has four flat sides. Compared with hexagon forms, the square shape gives more bearing area against the joined surface and corners that resist rounding when tightened with a spanner. Square nuts also sit in channels and slots without turning. They are used in older plant designs, railway and transmission line hardware, timber construction, channel supports and as replacements on existing equipment built with square fasteners.

Key features

  • Square bolts to ASME B18.2.1
  • Square and heavy square nuts to ASME B18.2.2; metric square nuts to DIN 557
  • Carbon steel, alloy steel and stainless steel grades
  • Large bearing face; nut does not rotate in channels
  • Plain, zinc or hot-dip galvanised finish

Specification

SupplyOEM manufacturer — Teshi Group, India
StandardASME B18.2.1 (square bolts), ASME B18.2.2 (square and heavy square nuts), DIN 557 (metric square nuts)
Grades — carbon steelASTM A307 Gr A / B, ASTM A563 nuts, SAE J429 Gr 2 / 5 / 8, ISO 898-1 class 4.6, 5.6, 8.8, 10.9, 12.9; ASTM F3125 (A325, A490)
Grades — alloy steelASTM A193 B7, B7M, B16; nuts ASTM A194 2H, 2HM, 3, 7, 7M, 16
Grades — low-temperatureASTM A320 L7, L7M, L43; nuts ASTM A194 7 / 7M with S3 impact test
Grades — high-temperatureASTM A453 Gr 660 (A286, UNS S66286); ASTM A193 B16
Grades — stainless steelASTM A193 / A320 B8, B8M, B8T, B8C (Class 1 and Class 2); nuts ASTM A194 8, 8M, 8T, 8C, 8F; ISO 3506 A2-70, A4-70, A4-80; ASTM F593 / F594
Grades — 904L and 6Mo904L (UNS N08904), 254 SMO / 6Mo (UNS S31254)
Grades — duplex and super duplexDuplex UNS S31803 / S32205 and super duplex UNS S32750 / S32760 (ASTM A1082 bolting, A276 / A479 bar)
Grades — nickel alloysMonel 400 (ASTM B164, N04400), Monel K-500 (B865, N05500), Inconel 600 (B166, N06600), Inconel 625 (B446, N06625), Inconel 718 (B637, N07718), Incoloy 825 (B425, N08825), Hastelloy C276 (B574, N10276), Alloy 20 (B473, N08020)
Grades — titaniumASTM B348 Grade 1, 2, 5 (Ti-6Al-4V), 7, 12
Grades — copper-nickelCu-Ni 90/10 (C70600) and 70/30 (C71500) against order
Grade availabilityEvery grade listed is made or supplied against order, with EN 10204 3.1 certificates (3.2 / third-party inspection when specified) and PMI on alloy, stainless, duplex and nickel grades.
ThreadsUNC, ISO metric coarse
FinishPlain, zinc electroplated, hot-dip galvanised
DocumentsEN 10204 3.1 mill test certificate (3.2 / third-party inspection when specified), dimensional inspection report

Applications

  • Replacement fasteners on older plant and machinery
  • Railway and transmission line hardware
  • Strut channel and cable support systems
  • Timber and heavy construction

FAQ

Square Head Bolts & Square Nuts: common questions

Why use square nuts instead of hex nuts?

Square nuts have more bearing area and their flat sides stop them turning in slots and channels, so they can be held without a second spanner.

Which standard covers square nuts?

ASME B18.2.2 covers inch square nuts and heavy square nuts, along with the other inch nut types. DIN 557 covers metric square nuts. Square head bolts are covered by ASME B18.2.1.

Can you match old square bolts on existing equipment?

Yes. Send a sample or a drawing showing thread size, length, head size and material grade, and we will manufacture matching square head bolts and square nuts for the existing equipment.

Are square head bolts available in stainless steel?

Yes. Square head bolts and square nuts can be made in 304 and 316 stainless steel for corrosive or outdoor service, as well as in carbon steel and alloy steel grades.

Need a size or grade not listed here?

Our engineering team manufactures against your drawing or datasheet, with dimensional sign-off before dispatch.

Send us your specification

Traceability

From mill heat to your site

  1. 01

    Approved mill material

    Received against the mill certificate; heat number registered.

  2. 02

    Forging & machining

    Heat number carried through every stage in our Indian works.

  3. 03

    PMI, dimensional & NDT

    Every lot inspected to the governing standard; TPI witness on request.

  4. 04

    Stamped & certified dispatch

    Hard-stamped pieces with EN 10204 3.1 / 3.2 certificates.

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