Riveted joints are permanent mechanical fasteners used to join two or more components by plastically deforming a rivet. They are widely used in structural, mechanical and pressure vessel applications due to their reliability and resistance to vibration.
This page provides a complete engineering guide to riveted joints including types of rivets, strength calculations, failure modes, design assumptions and practical formulas used in mechanical design.
Contents: Types of rivets, strength calculations, materials, stresses, failure modes, efficiency and blind rivets.
A riveted joint is a permanent fastening method where a metal rivet is inserted into aligned holes and deformed to clamp components together. The joint strength depends on rivet shear, plate tensile strength and bearing stress.
The two main types of riveted joints are lap joints and butt joints. Lap joints overlap the plates being joined, while butt joints connect plates edge-to-edge using cover plates. The choice depends on strength requirements, load direction and joint design.
Rivets are considered to be permanent fasteners. Riveted joints
are therefore similar to welded and adhesive joints. When considering
the strength of riveted joints similar calculations are used as for bolted joints.
Rivets have been used in many large scale applications including shipbuilding,
boilers, pressure vessels, bridges and buildings etc. In recent years
there has been a progressive move from riveted joints to welded, bonded and even
bolted joints A riveted joint, in larger quantities is sometimes cheaper than the other options but it requires
higher skill levels and more access to both sides of the joint
There are strict standards and codes for riveted joints used for structural/pressure vessels
engineering but the standards are less rigorous for using riveted joints in general
mechanical engineering.
A rivet is a cylindrical body called a shank with a head. A hot rivet is inserted into a hole passing
through two clamped plates to be attached and the head is supported whilst a head is
formed on the other end of the shank using a hammer or a special shaped tool. The plates are
thus permanently attached. Cold rivets can be used for smaller sizes the - forming processes being
dependent on the ductility of the rivet material...
When a hot rivet cools it contracts imposing a compressive (clamping) stress on the
plates. The rivet itself is then in tension the tensile stress is approximately equal to
the yield stress of the rivet material
The notes below are assuming that the plate loads are withstood by the rivets. In practice
the loads are generally withstood by friction between the plates under the compressive force
of the contracted rivets. The calculations provided below are simplified
but provide relatively conservative joint strength value. There is still a need to
complete fatigue assessments on joints when relevant
There are two basic types of axial riveted joint the lap joint and the butt joint.
The selection of the number of rivets used for a joint and the array is simply to ensure
the maximum strength of the rivets and the plates. If ten small arrayed rivets on a lap
joint were replaced by three large rivets across a plate the plate section area (in tension) would clearly
be significantly reduced...
Rivets for mechanical and structural applications are normally made from ductile (low carbon ) steel
or wrought iron. For applications where weight, corrosion, or material
constraints apply, rivets can be made from copper (+alloys) aluminium (+alloys),monel etc.
For rivets used for structures and vessels etc the relevant design stresses are provided
in the applicable codes. For rivets used in mechanical engineering, values are available
in mechanical equipment standards which can be used with judgement.
BS 2573 Pt 1 Rules for the design of cranes includes design stress values based on the
Yields stress (0,2% proof stress) YR0.2 as follows:-
Hand driven rivets ..tensile stress (40%YR0.2) ..Shear (36,6%YR0.2)..Bearing (80%YR0.2)
Machinery's handbook includes some values for steel rivets . I have intepreted these values and include
them below as rough approximate values for first estimate. These are typical values
for ductile steel. Tensile (76MPa) .. Shear (61MPa) ..Bearing (131MPa)
In designing rivet joints it is convenient to simplify the process by making the following assumptions.
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A rivet joint may fail as a result of one( or more) of a number mechanisms..
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The rivet joint efficiency is simply described as follows
Eff = Max Allowable Force applied to Rivet Joint/ Plate Strength with not holes
The joint efficiency is increased by having multiple rows of rivets. It is also clear that the efficiency can never be 100% . The maximum allowable force is the smallest of the allowable shear, tensile or bearing forces.
Rivets are initially sized with nominal diameters of between 1,2√ t and 1,4 √t (t = plate thickness)
The diametrical clearance provided for hot rivets is about 1,5mm max. For cold
rivets very tight fits are often provided by using reamed holes. It is important
that the rivets are not positioned too close to the side of the plate or the edge of a
plate. m t should be greater than 1,5 d and m a should be
greater than 1,5 d. (d = nominal rivet diameter). It is also suggested that
the distance between rivets in the rows (pt) is greater than 3d and the
distance between rows (pa )is greater than 3 d. Uisng these
guidance factors the strength calculations are simplified
Rivets calculations are generally completed to check for three failure modes : rivet shear,
plate tensile failure, and rivet /plate bearing..These are shown below. A
rivet joint can also fail due to plate shearing (tearing )behind the rivet.
This calculation is not always completed because the joint design should include that the minimim metal land behind the
rivet (ma above )is specified ensuring that other failure modes will operate before this mode.
It is also important that the axial pitch (p a ) is maximised (see above note )to
ensure that the weakest section of the plate is through a row of holes
Rivet Shear
The rivet shear calculation is
τ = F / ( n p d 2 /4 )
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Plate Tensile Stress
The tensile stress in the plate =
σt = F / [t (w - n r d 1)
|
Plate /rivet bearing stress
The Plate/Rivet bearing stress =
σc = F /(n d t)
Plate tearing stress..
The plate shear stress =
τc = F /(2 m a t)
Note: The Standard BS 4620 has been declared obsolescent as it is no longer used for current technologies....
| Nom Shank dia |
Dia Tol |
60 Deg Csk & Raised Csk | Snap Hd | Universal Hd | |||||
| Nom dia | Raise Ht | Nom dia | Nom Depth | Nom dia | Nom Depth | Rad | Rad | ||
| D | W | D | K | D | K | R | r | ||
| 14 | +/- 0,43 | 21 | 2,8 | 22 | 9 | 28 | 5,6 | 42 | 8,4 |
| 16 | +/- 0,43 | 24 | 3,2 | 25 | 10 | 32 | 6,4 | 48 | 9,6 |
| 18 | +/- 0,43 | 27 | 3,6 | 28 | 11,5 | 36 | 7,2 | 54 | 11,0 |
| 20 | +/- 0,52 | 30 | 4,0 | 32 | 13 | 40 | 8,0 | 60 | 12,0 |
| 24 | +/- 0,52 | 33 | 4,4 | 36 | 14 | 44 | 8,8 | 66 | 13,0 |
| 24 | +/- 0,52 | 36 | 4,8 | 40 | 16 | 48 | 9,6 | 72 | 14,0 |
| 27 | +/- 0,62 | 40 | 5,4 | 43 | 17 | 54 | 10,8 | 81 | 16,0 |
| 30 | +/- 0,62 | 45 | 6,0 | 48 | 19 | 60 | 12,0 | 90 | 18,0 |
| 33 | +/- 0,62 | 50 | 6,6 | 53 | 21 | 66 | 13,2 | 99 | 20 |
| 36 | +/- 0,62 | 55 | 7,2 | 58 | 23 | 72 | 14,4 | 108 | 22 |
| 39 | +/- 0,62 | 59 | 7,8 | 62 | 25 | 78 | 15,6 | 117 | 23 |
| Non-Preferred sizes |
Note: The Standard BS 4620 has been declared obsolescent as it is no longer used for current technologies....
| Nominal Shank dia | Dia Tol |
90 Deg Csk | Snap Hd | Universal Hd | Flat Head | |||||
| Nom dia | Nom dia | Nom Depth | Nom dia | Nom Depth | Rad | Rad | Nom dia | Nom Depth | ||
| D | D | K | D | K | R | r | D | K | ||
| 1 | +/- 0,07 | 2 | 1,8 | 0,6 | 2 | 0,4 | 3,0 | 0,6 | 2 | 0,25 |
| 1,2 | +/- 0,07 | 2,4 | 2,1 | 0,7 | 2,4 | 0,5 | 3,6 | 0,7 | 2,4 | 0,3 |
| 1,6 | +/- 0,07 | 3,2 | 2,8 | 1,0 | 3,2 | 0,6 | 4,8 | 1,0 | 3,2 | 0,4 |
| 2,0 | +/- 0,07 | 4 | 3,5 | 1,2 | 4 | 0,8 | 6,0 | 1,2 | 4 | 0,6 |
| 2,5 | +/- 0,07 | 5 | 4,4 | 1,5 | 5 | 1 | 7,5 | 1,5 | 5 | 0,8 |
| 3 | +/- 0,07 | 6 | 5,3 | 1,8 | 6 | 1,2 | 9,0 | 1,8 | 6 | 0,9 |
| 3,5 | +/- 0,09 | 7 | 6,1 | 2,1 | 7 | 1,4 | 10,5 | 2,1 | 7 | 1,0 |
| 4 | +/- 0,09 | 8 | 7 | 2,4 | 8 | 1,6 | 12 | 2,4 | 8 | 1,3 |
| 5 | +/- 0,09 | 10 | 8,8 | 3,0 | 10 | 2,0 | 15 | 3,0 | 9 | 1,5 |
| 6 | +/- 0,09 | 12 | 10,5 | 3,6 | 12 | 2,4 | 18 | 3,6 | 10 | 1,8 |
| 7 | +/- 0,11 | 14 | 12.3 | 4,2 | 14 | 2,8 | 21 | 4,2 | 14 | 2,0 |
| 8 | +/- 0,11 | 16 | 14 | 4,8 | 16 | 3,2 | 24 | 4,8 | 16 | 2,5 |
| 10 | +/- 0,11 | 20 | 18 | 6,0 | 20 | 4,0 | 30 | 6,0 | 20 | |
| 12 | +/- 0,14 | 24 | 21 | 7,2 | 24 | 4,8 | 36 | 7,2 | ||
| 14 | +/- 0,14 | 25 | 8,4 | 28 | 5,6 | 42 | 8,4 | |||
| 16 | +/- 0,14 | 28 | 9,6 | 32 | 6,4 | 48 | 9,6 | |||
| Non-Preferred sizes |
Solid rivets require access to both sides of a joint and require some skill for correct
installation. Blind rivets have been developed to solve both of these
shortcomings.
Blind rivets are available in a range of body styles such as open , closed end ,multi-grip, and peel
with head styles in dome, countersunk and large flange and in materials such as
aluminium, steel, nickel copper, copper, plastic and stainless steel.
Blind rivets are normally supplied in sizes up to 8mm and able to clamp two plates with
total thickness up to 25mm (normal) 50mm (special). For steel rivets which
are not as ductile as copper /aluminium rivets the size limit is restricted to about 6mm.
This rivet is used where the joint has to be fluid pressure tight. The end include a sealed
end completely enclosing the head end of the mandrel and 100% mandrel head retention.
This feature combined with the fact that the rivet expands radially to fill the hole when set ensures that
the rivet will seal at pressures up to 35 bar
This type of rivet is used in soft materials including wood, plastic, glass fibre etc. It is
often used to fasten sheets of soft material to metals sheets. The peel type rivet
has a soft metal body e.g. aluminum with a stronger steel metal. On setting the the far
end of the rivet body splits into a number of petals creating a large blind side gripping area capable of
withstanding large pull out forces.
This type of pop rivet has been designed for use with thick sections of soft , or brittle material
e.g. hardboard, plywood,, glassfibre, asbestos board, brick, concrete etc.
These rivets include a shank with a number of grooves which protrude into the material to be
fixed. On setting these grooves are expanded to grip the material as opposed of the
rear face.
The strength of blind rivets as given in suppliers tables is generally the ultimate
strength at failure. In comparing the strength of blind rivets with
conventional solid rivets (same material ) the solid rivets are generally stronger than blind rivets
for the blind rivets where the blind rivet mandrel breaks off below the shear line.
For the blind rivets where the mandrel breaks off above the shear line the blind rivets
are generally stronger.
As an example for a 4mm blind rivet the shear strength quoted is 3,1kN (mandrel not
in shear plane) and 6,7kN (mandrel in shear plane. The ultimate shear
strength of a solid rivet of 4mm dia (assuming a shear strength of about 336 MPa) = 4.2 kN.
It must be noted that a blind rivet is normally used for lighter structures with thinner
section plates. It is generally accepted that a solid rivet correctly
installed is more reliable compared to a blind rivet but considerably more expensive
to fit.
For a joint using four 6 mm diameter rivets subjected to a total load of 10 kN, the shear stress in each rivet can be calculated using the standard shear equation.
A riveted joint is a permanent fastening method where a rivet is deformed to securely join two or more plates together.
The main types are lap joints, where plates overlap, and butt joints, where plates are joined edge-to-edge using cover plates.
Rivet strength is calculated based on shear stress, tensile stress in the plate and bearing stress between the rivet and plate.
Failure modes include rivet shear, plate tearing, bearing failure and tensile failure of the plate.
Rivet joint efficiency is the ratio of the strength of the riveted joint to the strength of the unperforated plate.