Grade 2 Hex Bolts and Nuts

Grade 2 hex bolts are the everyday, economical bolt for light-duty work: brackets, shelving, panels, conduit supports and the general repairs where nothing is pulling hard on the joint. They’re plain carbon steel with no heat treatment, so they’re softer than Grade 5 or Grade 8. That’s fine for the job they’re meant for, and the wrong choice for anything that takes real load or shakes.

Where Grade 2 belongs, and where it doesn’t

Use Grade 2 where the load is light or steady and there’s little shock: electrical cabinets, control panels, junction boxes, conduit supports, and general shop and farm repairs of that kind. Don’t use it where loads are high or change back and forth, under heavy vibration, or in structural connections governed by engineering codes. Those call for a higher grade or the bolt the plans specify.

The numbers explain why. For 1/4- through 3/4-inch diameters, Grade 2 has a minimum tensile strength of 74,000 psi. Above 3/4 inch, that drops to 60,000 psi. Grade 5 and Grade 8 are stronger. You can tell a Grade 2 at a glance: its head has no radial lines, while Grade 5 and Grade 8 heads are marked.

Being softer has one upside: Grade 2 steel is easier to cut, drill or re-thread at the bench when you need to modify a bolt.

Match the thread first

Every Grade 2 bolt WBC carries here is “NC”: national coarse thread. Coarse and fine threads can share a diameter and still not fit each other, so a coarse-thread bolt won’t run into a fine-thread nut or tapped hole. When you’re replacing a bolt, bring the old one and the nut, and check the thread at the counter before you check anything else.

Diameter and length

Diameter is the thickness of the shank. Length runs from the underside of the head to the tip; the head doesn’t count. Buy a bolt long enough to pass through everything you’re clamping, plus the washers and the nut, with a couple of threads showing past the nut. Much longer just leaves bolt to snag on things.

WBC carries Grade 2 hex bolts in 1/4-, 5/16-, 3/8-, 1/2-, 5/8- and 3/4-inch diameters, in lengths from 1/2 inch up to 12 inches. For example:

Diameter	Some of WBC’s lengths
1/4 inch	1/2, 2-1/2, 3, 3-1/2, 4 inches
1/2 inch	1, 1-1/2, 3-1/2, 4, 4-1/2, 5, 5-1/2, 6, 7, 7-1/2, 8 inches
5/8 inch	2, 4, 5, 6, 7, 7-1/2, 8, 9 inches
3/4 inch	2-1/2, 8, 9, 12 inches

Some Grade 2 bolts are threaded only part of the way, with a smooth shank under the head; others are threaded the full length. Fully threaded bolts work for running into a tapped hole and through-bolting alike; a partly threaded bolt puts the smooth shank where the parts meet.

Nuts, washers and finish

Pair Grade 2 bolts with Grade 2 nuts and standard flat washers, and buy them together. A stronger nut doesn’t make a weaker bolt stronger.

Plain steel rusts quickly outdoors. For anything outside, choose zinc-plated bolts for basic corrosion resistance or galvanized for better outdoor life. Montana’s spring snowmelt keeps ground-level hardware wet for weeks, so a fence bracket or a trailer-gate repair near the ground gets galvanized, not plain.

The Pick

For light-duty, non-critical repairs, buy Grade 2 hex bolts with Grade 2 nuts and flat washers. Match the coarse thread to the nut or hole first, then pick the diameter, then a length that clears the nut by a couple of threads. Go zinc-plated or galvanized outdoors. For anything that carries a heavy or shifting load, vibrates, or is structural, step up to the grade the job calls for.

Frequently Asked Questions

What are Grade 2 bolts used for?

Light or steady loads with little shock: electrical cabinets, junction boxes, conduit supports, brackets, shelving and general repairs. They aren’t for high or fluctuating loads, heavy vibration or structural connections; those need a higher grade.

How strong is a Grade 2 bolt?

For 1/4- through 3/4-inch diameters, minimum tensile strength is 74,000 psi; above 3/4 inch, it’s 60,000 psi. Grade 5 and Grade 8 are stronger. A Grade 2 head has no radial grade lines.

What does NC mean on a bolt?

National coarse thread. A coarse-thread bolt only fits a coarse-thread nut or tapped hole of the same diameter. Fine thread is a different pitch, so check the thread when replacing a bolt.

How long a bolt do I need?

Long enough to pass through all the parts, the washers and the nut, with a couple of threads showing beyond the nut. Length is measured from under the head to the tip.

What nuts should you use with Grade 2 hex bolts?

Grade 2 nuts and standard flat washers. A stronger nut won’t raise the bolt’s capacity, so match the grade the job needs in the bolt itself.