The rivet body is a tube open at both ends, so once set there is a hole straight through the joint.

That is harmless in a bracket or an interior panel and unacceptable in anything that must keep water, air or light out.

No amount of tightening changes it, because a set rivet cannot be tightened.

Sealant over the head is a repair rather than a detail and has a short life.

Where the joint must seal, a closed-end rivet is the correct part from the start.

This is the single decision that separates the two most common rivet types.

It stays loose inside most open-end rivets, and it can work free under vibration.

The mandrel snaps at a designed break point once the head has formed, leaving a short stub in the body.

In an open-end rivet nothing retains that stub except friction.

Vibration can free it, after which it rattles inside a hollow section or falls out.

In electrical enclosures a loose metal fragment is a genuine hazard rather than a nuisance.

Structural blind rivets lock the mandrel deliberately, which is one of the things that makes them structural.

The total material thickness the rivet is designed to clamp, and it decides whether the joint is actually tight.

Below the minimum, the blind-side head forms clear of the material and the joint stays loose.

Above the maximum, the mandrel breaks before the head has formed properly.

Both failures look identical from the accessible face, which is what makes them dangerous.

Grip range is printed on every pack and is the primary selection criterion after diameter.

Where the thickness varies, a multi-grip rivet covers a wider range at slightly lower strength.

The manufacturer's stated diameter, drilled cleanly and deburred - a close fit is part of the mechanism.

The body must fill the hole to clamp the sheets together.

An oversized hole lets the body expand sideways instead, and the joint has play in it immediately.

Too tight and the rivet cannot be inserted, or is damaged forcing it in.

Burrs prevent the flange and the formed head bearing flat.

Worn or reground bits drill oversize, so the bit matters as much as the number printed on it.

Matched to the sheets where possible, stainless where they differ or the joint is exposed.

A riveted panel has many holes, so any galvanic couple is repeated many times over.

Aluminium rivets suit aluminium and thin sheet and set easily by hand.

Steel rivets are stronger and generally need a lever or powered tool.

Stainless resists corrosion and is the usual answer outdoors and in washdown areas.

The mandrel material counts too - a steel mandrel left inside an aluminium rivet is itself a couple, which is why all-aluminium versions exist.

Modest shear and less tension - published values are per rivet, per material and per grip range.

Blind rivets are designed for panel and light assembly work rather than for structural connections.

Shear is the favourable direction, with the rivet body loaded across its diameter.

Tension pulls against a formed head that was upset rather than machined, and is weaker.

Spreading load across more rivets is far more effective than choosing a larger one.

Where real strength is needed, structural blind rivets or bolts are the correct answer.

Drill out the head with a bit matched to the body, then punch the remains through.

Centring the drill on the mandrel hole keeps it true and protects the parent hole.

Drill only through the head; once separated, the body pushes out with a punch.

Backing the material while punching prevents distortion in thin sheet.

If the hole has been enlarged by an off-centre drill, the replacement should be a larger or large-flange rivet.

Closed-end and structural rivets are harder to remove, so an open-end rivet is the easiest of the family to undo.