Product and assembly brief
This selector identifies the large, low round-head square-neck step-bolt form. Similar underhead construction does not make it interchangeable with an ordinary carriage bolt. A tower or pole climbing component called a step bolt requires its own controlled assembly drawing and acceptance documents; a product name or illustration is not a safety qualification.
Product forms and reference names
| Choice or field | What to identify |
|---|---|
| Inch-series step form | ASME's B18.5 public description distinguishes the step form by its larger head relative to a round-head square-neck bolt. Specify the selected inch form and document edition; no normative dimensions are given here. |
| Ordinary carriage form | The existing carriage detail is a related selector, not proof of step-bolt head geometry. Compare head diameter/height, square-neck geometry and the receiving component before any substitution. |
| Other low-head constructions | A comparatively flat elevator head and a timber bolt with underhead fins are separate constructions. Head silhouette alone cannot identify the intended product. |
| Drawing-specific access component | If an enquiry concerns a pole or tower step assembly, supply the original component and assembly drawing, mounting interface and acceptance requirements. No generic climbing, fall-protection or installation approval is asserted. |
Large head and square-neck interface
Specify the head envelope, bearing underside, square-neck width and axial height, transitions and receiving-hole geometry. Treat the actual component drawing as authoritative; a render cannot establish dimensional tolerances or anti-rotation performance.
Thread, plain shank and length datum
Identify metric or inch thread system, pitch and fit, the specified length measurement convention, thread length and any plain-shank region. A nominal diameter and overall appearance do not define the complete bolt.
Material, finish and mating components
Declare the required material/property specification and coating separately from geometric identity. List every nut, washer and other selected component, including mating-thread and finish requirements. No maker's stock, size range or certification is transferred to FastenerBridge.
Access duty is not qualification
Where the part is intended for a pole or tower, the complete mounting arrangement, use conditions and original assembly-specific qualification and installation documents must be reviewed by the responsible parties. This page supplies no load value, climbing instruction, tightening torque, tool compatibility or fall-arrest suitability.
Standard identity and source boundaries
The official publisher displays ASME B18.5-2012 (R2023) for inch-series round-head bolts and explains that other documents address threads, materials, mechanical properties and finishes. This identity does not prove a supplied part conforms or establish equivalence to DIN 603 or a withdrawn historical metric large-head reference.
Specification fields
| Choice or field | What to identify |
|---|---|
| Reference and purpose | Selected product form, standard and edition or controlled drawing revision; distinguish ordinary fastening from drawing-specific access duty. |
| Head and neck | Head diameter/height/profile, bearing underside and integral square-neck dimensions/transitions with controlled tolerances. |
| Receiving component | Hole/recess geometry, material and thickness, bearing arrangement, mating stack and available space from the actual component drawing. |
| Thread and length | Metric or inch designation, pitch/fit, length datum, threaded length, plain-shank and end requirements. |
| Material and finish | Material/property specification, treatment/coating and mating fit; required traceability and inspection documents. |
| Assembly and order | Component list, original assembly acceptance/installation documents where applicable, quantity in bolts or sets, packing and destination. |
Common product questions
Is a step bolt simply a stepped-shank shoulder bolt?
No. The inch step-bolt reference here concerns a large round head and square neck, not a generic stepped shank. Confirm the requested drawing when names differ.
Can a normal carriage bolt replace this form?
Do not assume so. Related square-neck construction does not establish the same head envelope, receiving fit or complete specification.
Does this page qualify a bolt for tower climbing?
No. Obtain the controlled original assembly and qualification documents. Neither a catalogue name, a standard number nor an AI appearance image supplies safety or installation approval.
Related product choices
- Ordinary square-neck carriage bolt selector
- Underhead-fin timber bolt selector
- Oval-neck guardrail interface selector
Product references
References checked 10 October 2026 identify structures, not FastenerBridge stock, compliance or brand affiliation. Final requirements follow the selected specification. No normative dimension, load rating or tightening torque is stated.