Stainless Steel J Bolt

Choosing the Right J-Bolt (J-Type Anchor Bolt)
1) What is a J-bolt & when to use it?

A J-bolt is an anchor bolt with a threaded straight leg on one side and a curved “J”-shaped hook on the other.
The hook end is normally cast into concrete or hooked around reinforcement/steel, while the threaded end is used with nuts & washers to hold down structures.

Use a J-bolt when you need a fixed anchor in concrete for:

Base plates & structural columns

Machinery skids and equipment frames

Poles, sign boards, masts, and gantries

Pipe supports, platforms, handrails, and guards

The curved “J” provides a larger bearing area in concrete versus a simple straight bar, improving resistance to pull-out.

2) Environment & corrosion – material / finish selection

Choose the material based on exposure and design life:

Carbon steel (plain / zinc plated / hot-dip galvanized)

Standard option in general civil & structural foundations

HDG (hot-dip galvanized) is widely used for outdoor foundations (columns, poles, etc.)

A2 (304) stainless J-bolt

For indoor & general outdoor environments where corrosion control is important

Suitable for stainless base plates, food plant interiors, and clean environments

A4 (316) stainless J-bolt

For marine, coastal, chemical, and chloride-rich environments

Ideal for jetties, waterfront structures, treatment plants, chemical plants, poolside foundations

Rule of thumb:

General structural foundations → HDG carbon steel J-bolts

Stainless equipment / clean or corrosion-sensitive areas → A2 stainless

Harsh marine / high-chloride / chemical → A4 stainless

Always match nuts & washers to the same material/finish (HDG with HDG, A2 with A2, A4 with A4).

3) Diameter – choosing the right size

Select bolt diameter (M10, M12, M16, M20, M24, etc.) based on:

Required tension (uplift) and shear capacity

Weight & size of the connected structure or equipment

Wind, seismic, and dynamic loads, according to structural design

Typical ranges (just as a guide; final by engineer):

Light poles, small supports, light equipment → M10–M16

Structural columns, heavier equipment, gantries → M16–M24+, as per calculation

4) Hook length & embedment depth – key to holding power

For J-bolts, the curved hook and embedment depth are critical:

Hook portion (curved “J”)

Provides a mechanical key in the concrete

Longer, well-shaped hooks improve resistance to pull-out and straighten-out

Embedment depth (hef)

Vertical depth of the hook into the concrete

Influences concrete breakout and bond capacity

Correct design must consider:

Bolt diameter

Required load and safety factors

Concrete strength, thickness, edge distance & spacing

Too short hook or shallow embedment → risk of pull-out or concrete breakout under tension.

Mechanical Properties (Guide) – J-Bolts (Anchor J-Bolts)

A J-bolt’s performance is controlled by steel strength and concrete capacity.
Even strong steel can fail by anchor pull-out, hook straightening or concrete breakout if embedment and edge distance are insufficient.

Stainless J-Bolts – A2 / A4

A2-70 & A4-70 J-bolts

Material:

A2 (304) or A4 (316) stainless steel

Property class: 70

Minimum tensile strength ≈ 700 MPa

Typical proof strength ≈ 450 MPa

Use with: A2-70 / A4-70 nuts and washers of matching grade

Typical applications

A2 J-bolts:

Anchoring stainless structures, supports, equipment bases in normal environments

When aesthetics and corrosion control are both important

A4 J-bolts:

Anchoring structures and equipment in marine, coastal, or chemical atmospheres

Foundations in water treatment, offshore platforms, chemical plants, pool decks, etc.

A4-80 J-bolts (if used)

Material: high-strength A4 (316) stainless

Property class: 80

Minimum tensile strength ≈ 800 MPa

Typical proof strength ≈ 600 MPa

Used where higher tensile capacity and superior corrosion resistance are both required.