of 13
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
1/13
Corus Tubes library publication
The contents of this publication are current, when republishedit will be in the new Corus housestyle.
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
2/13
SHS Jointing
Flowdrill &
Hollo-Bolt
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
3/13
Flo
wdrill&
Hollo-B
olt Flowdrill &
Hollo-BoltJointing
for Hollow Sections
Flowdrill and Hollo-Bolt give a choice of two
methods to produce bolted joints in
Hollow Sections. Both systems offer the
following benefits:
q They produce bolted joints of structuralcapacity in Hot Finished Rectangular HollowSections (HFRHS).
q They minimise the change in the fabricationprocess by using connection details whichare standard in the construction industry.
q They reduce fabrication by removing theneed to weld plates or other fittings onto theoutside surface of the RHS.
q They simplify erection by using fully threadedbolts -an increasing practice in theconstruction industry.
q They maintain aesthetics by producing aflush face on the RHS after fabrication.
Design GuidanceThe design guidance produced in thispublication is for Flowdrill and Hollo-Boltsystems with grade 8.8 bolts in conjunction withTubes and Pipes hot finished structural hollowsections. The design guidance, for joints insimple construction, result from Tubes & Pipesinitial research work undertaken in connectionwith CIDECT (Ref. 1). The guidancecomplements the information published by theBCSA/SCI and is presented in a form
compatible with their publication Joints inSimple Construction (Ref. 2).
Further test work is being undertaken toestablish design guidance for semi-rigidjoints.
Procedural checks are given for bearing, shearand local bolt pull out of the RHS wall and forthe combined effect of the column axial loadand the structural integrity tensile load ofBS 5950 : Part 1.
The combined check for the column axial loadand the structural integrity tensile load
recognises that the flexibility of the RHS facecaused by the tensile load can, in the presenceof the column axial load, reduce the overall jointcapacity.
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
4/13
Flowdrill Hollo
-B
oltFabrication and
ConstructionGeneral detailing recommendations for beam
column connections, given in this
publication, are in accordance with the
BCSA/SCI publication -Joints in Simple
Construction (Ref. 2).Both Flowdrill and Hollo-Bolt use fully threaded
bolts which allows standardisation of bolt
lengths throughout the construction. Where
beams are connected to adjacent faces of an
RHS column a check must be made with the
chosen bolt length to ensure that assembly is
possible (see Fig. 3 and 6) and the bolts do
not touch.
Both Flowdrill and Hollo-Bolt are suitable for use
with the two standard grades of Tubes & Pipes
SHS to BS EN10210-1 of S275J2H and
S355J2H (formerly BS4360 Gr43D and 50Drespectively).
At present, application of the Flowdrill process
is limited to RHS thicknesses up to and
including 12.5mm. For thicknesses of 16mm
and over, conventional drill and tap methods are
recommended, although due to the RHS
material strength being lower than that of the
grade 8.8 bolts, pull out strengths may be below
the bolt tension capacity.
Reference
1. Comit International pour leDveloppment et ltude de laConstruction Tubulaire
UK Member
British Steel plcTubes & Pipes
PO Box 101
Corby
Northants NN17 5UA
2. Joints in Simple Construction
Volume 1 : Design methods
Volume 2 : Practical applications
Published jointly by:
BCSA SCI4 Whitehall Court Silwood Park
Westminster Ascot
London Berks SL5 7QN
SW1A 2ES
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
5/13
Flow
dril
lThe ToolsThe initial hole is made by a Flowdrill tool
consisting of a tungsten carbide bit held in a
Flowdrill Morsetaper collet adaptor (Fig. 1). The
tool can be used in a conventional drilling
machine or CNC machine as found in
fabricators works, provided it has adequate
horsepower and spindle speed.
1st stageThe tungsten carbide bit is brought into contact
with the RHS wall where it generates sufficient
heat to soften the steel. The bit is then
advanced through the wall and in so doing the
metal is redistributed (or flows) to form an
internal bush. As well as drilling the initial hole,
the tool is fitted with the means of removing any
surplus material which may arise on the outside
of the RHS section. The cycle time for
Flowdrilling is similar to that for conventional
drilling. However, if done on CNC machines the
feed rate can be slow at the beginning, rapidly
increasing as the material softens to improve
efficiency.
2nd stageThe 2nd and final stage is to tap the Flowdrill
bush. This is done by roll threading the bush
with a Coldform Flowtap. The complete cycle is
shown in Figure 2.
TheProcess
Flowdrill data :
The Flowdrill system was developed by Flowdrill BV in Holland, and is available in the UK from
their agent - Robert Speck Ltd,. Little Ridge, Whittlebury Road, Silverstone, Northants NN12 8UD.
Tel: 01327 857307 Contact Mr Mike Carpenter.
Flowdrill Flowdrilling is basically a thermal drillingprocess which makes a hole through thewall of a structural hollow section without
the removal of metal normally associated
with a drilling process. The formed hole is
then threaded by the use of a roll thread
forming tool, leaving a threaded hole which
will accept a standard fully threaded bolt.
Tool holder
Collet
Flowdrill bit
Fig. 1
Fig. 2
1st Stage 2nd Stage
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
6/13
Drilling machine parameters :
Table 1 gives a guide to required machine
parameters for producing Flowdrill holes for
M12 to M24 bolts:
Note: The Flowdrill process is not suitable for
hand held or magnetic clamp type drilling
equipment when used in the sizes shown.
Flowdrill detailing requirements.
See Fig. 3 and Table 3.
Note:
q Flowdrilled joints used at
locations exposed to the
weather should not be
considered as water tight.
q Flowdrilling is not suitable
for use with pre-galvanised
materials.
Drill length: The recommended length ofFlowdrill bits varies with the thread size andthickness of material as given in Table 2.
Drill care: Flowdrills are made from tungstencarbide. They are extremely hard but cannotwithstand shock loads. After drilling each hole,FD KS paste should be applied to the Flowdrill
whilst it is still hot, so minimising oxidation andpreventing build up on the surface.
Flat surface: the raised rim on the outer surfaceof the RHS material caused during Flowdrillingshould be removed using Flowdrills with cuttingedges provided on the collar. One rotation of thecutter is all that is required to remove the rim.
Table 1
Table 2
Table 3 (See Fig. 3 for nomenclature)
Thread size
Flowdrill size
M/c spindle
speed rpm
M/c feed rate
Motor power
KW Min
Tapping speed
rpm
M12
10.9
1000-1500
2
250
M16
14.8
700-1100
2.5
200
M20
18.7
600-1000
3.5
150
M24
22.5
500-800
5
100
0.1/0.15mm (0.004/0.006 inches) per rev
Flowdrill Length
Thread SizeMax materialthickness
(mm)
3
5
6
8
10
12
16
M12
Short
Long
Long
Long
-
-
-
M16
Short
Short
Long
Long
Long
-
-
M20
Short
Short
Short
Long
Long
Long
-
M24
Short
Short
Short
Long
Long
Long
-
Dimensions
(mm)
A1
B1
C1
D1
E1 Minimum
Min Bolt Centres
M12
7
13
18
30
M16
10
17
20
40
M20
12
22
26
50
M24
15
25
29
60
Thread size/Bolt diameter
Varies with overall bolt length (Lb) specified
C1/2 + tc (for connection made to a single face or opposite faces)
B1/2 + A1 + D1 + tc (for connection made to adlacent faces)
E1
tp
tc
Lb
E1
B1
A1
D1
C1
Min bolt centres
Width
Fig. 3
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
7/13
Holl
o-Bolt
Hollo-Bolt
The pre-assembled unit (Fig. 4) is
inserted through normal tolerance holes
in both the attatchment plate and the
RHS. As the bolt is tightened the cone is
drawn into the body, spreading the legs,
and forming a secure fixing. Once
installed only the Hollo-Bolt head and
collar are visible (Fig. 5).
The Hollo-Bolt
HOLLO-BOLT is a pre-assembled
three part fitting consisting of body,
cone and bolt.
Further information on
Hollo-Bolt is available from
Lindapter International
A Division of Victaulic plc.,Lindsay House, Brackenbeck Road,
Bradford, West Yorkshire, Tel: 01274 521444
England, BD7 2NF Fax: 01274 521130
Hexagon Head
Location Flats
Body
Cone Knurling
Collar
Fixture
RHS
Cone
Legs
Central Bolt
Fig. 4
Fig. 5
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
8/13
Drilling requirements:
Hollo-Bolt uses a plain drilled
hole which can be made on
site or in the fabrication shop
using all normal drilling
equipment. The finished hole
should have a tolerance of
-0.2mm to +1.0mm from the
nominal given in the data table(Table 4).
Material Options
Standard product is manufactured from mild
steel and is electro-zinc plated with the addition
of JS500 1000 hour saltspray corrosion
protection. The central fastener is a grade
8.8 bolt.
For special applications, the Hollo-Bolt is
available manufactured from 316 stainless steel,
with a grade A4-80 central bolt. This will not be a
stocked item, and would be manufactured to
order.
Installation
The only tools required to fit Hollo-Bolt are two
spanners - an open ended spanner to hold the
collar and a torque wrench to tighten the central
bolt. Alternatively a power operated electrichand tool is in development.
Should the steelwork need to be adjusted,
the fixing can simply be removed and the
hole reused with another Hollo-Bolt.
Sealing Options
In certain applications, it may be necessary to
seal the Hollo-Bolt to prevent ingress of water or
other corrosive agents. For details of sealing
options available, please contact Lindapter.
Special Options (manufactured to order)q Stainless steel
q Button head setscrew q Socket head capscrew
q Countersunk setscrew/body q Special body lengths
Table 4 (See Fig. 6 for nomenclature)
Bolt
size
M8
M10
M12
M16
M20
Bolt
length
(V)
mm
45
49
53
57
80
Fixing
thickness
(W)
Min Max
mm
3 22
3 22
3 25
3 28
3 34
Bolt
centres
(X)
Min
mm
35
40
50
55
70
Internal
min. edge
distance
(Y)
mm
13
15
18
20
25
Edge
distance
(E1)
Min
mm
50-tp
55-tp
60-tp
65-tp
90-tp
Bolt
hole
dia.
(Dh)
mm
14
18
20
26
33
Across
flats
main
body
mm
19
24
30
36
46
Tightening
torque
Nm
21
40
78
190
300
E1
tp
tc
V
YX
W
Width
Fig. 6
Fig. 7
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
9/13
Simple connections between Universal
beams and RHS columns can be made
using double angle web cleats or
flexible end plates.
The following procedural checks are
compatible with the BCSA/SCI rules for
Joints in Simple Construction (Ref. 2).
Double Angle Cleats Flexible End Plates
Notes
q The cleats or end plates are generally positioned as close to the top flangeof the beam as possible to provide adequate positional restraint and a plate
length of at least 0.6D is usually adopted to give adequate torsional restraint
(BS 5950: Part 1, Table 9).
q Bolt gauge g: 90mm g 140mm, but g 0.3 x RHS face width B.
q Although it may be possible to satisfy the design requirements with tp< 8mm,
it is not recommended in practice because of the likelihood of weld
distortion during fabrication and damage during transportation.
q The plate thickness and gauge limitations apply equally to partial depth and
to full depth end plates.
If necessary, to comply with structural integrity requirements for a 75 kN tie force,
the connection must have at least 2 no. M20, Grade 8.8 bolts in tension with
/ 140mm, t 8mm and g 140mm.
Design ofJoints inSimple
Construction
Face of column Face of column
ID ID
g g
Length of cleat
I 0.6D
Length of plate
I 0.6D
Cleat thickness, tptp= 8mm or 10mm
Plate thickness, tptp= 8mm or 10mm
Flowdrill hole diameter, DhDh = d+2mm for d 24mmDh = d+3mm for d > 24mmFor Hollo-Bolt Dh see Table 4.
Bolt diameter, d Bolt diameter, d
End projection t1, approx 10mm
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
10/13
Basic Requirement
For Shear
Local shear and bearing capacity of theRHS column wall and bolts.
Q Pv_2
Pv = local shear capacity of
RHS column wall
= smaller of 0.6pycAv and
0.5 UscAvnetAv = [g/2 + (n -1) p = et] tc
with [et 5 d]
Avnet = Av - n d tcn = number of rows of bolts
p = bolt pitch
d = nominal bolt diameter (or
hole diameter in RHS
columns for Hollo-Bolt)
g = bolt gauge width
tc = RHS column wall
thickness
pyc = design strength of RHS
colunm wall (S275 = 275
N/mm2 : S355 =
355 N/mm2)
Usc = ultimate tensile strength
of RHS column wall
For bearing
Q Pbsc_2
Pbsc = bearing capacity of the RHS
column wall per bolt = d tc pbscpbsc = bearing strength of the RHS
column wall (S275 =
460 N/mm2 : S355 = 550 N/mm2)
Bolt Check (Table 5)
The single shear capacity for Flowdrill and
Hollo-Bolt can be taken as follows:-
Flowdrill
Bolt diameter
-
-
M12
M16
M20
M24
kN
-
-
31.6
58.9
91.9
132
Bolt diameter
M8
M10
M12
M16
M20
-
kN
12
25
38
75
100
-
Flowdrill
tc
p
p
p
g
Q/2 Q/2
Q
et
n rowsof bolts
Critical sections
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
11/13
Structural integrity-local bolt pull-out
of RHS colmn wall.
Note: This check is only needed if it is
necessary to comply with structural
integrity requirements.
Basic Requirement
Tie force Local bolts pull-out
resistances
Local bolt pull-out resistances
= 2 n Pp(si)
The local bolt pull-out design resistance
in kN of a grade 8.8 bolt in a flowdrilled
hole or a Hollo-Bolt should be taken from
the following tables which are based on
test results:
Note:
1. The tension capacity of Grade 8.8 bolts for
normal design and for structural integrity
design is shown in the shaded areas.
2. The pull-out resistances for structural
integrity Pp(si) are less than those for normaldesign because the design method
presented here for structural integrity leads
to thinner cleats or end plates than for
normal design methods, based on BS 5950:
Part 1, and, as a result, will lead to higher
prying forces. This has been taken into
account in the quoted resistances.
Flowdrill normal design strength (Pp(n)kN
RHS column wall thickness tc mm
Grade S275 (Grade 43) Grade S355 (Grade 50)
Bolt
diameter
mm
M16
M20
M24
6.3
60
85
101
8
95
122
10
70
97
134
12.5
110
159
5
59
102
103
6.3
130
70
110
8-12.5
159
5
46
70
80
Flowdrill structural integrity design strength (Pp(si)kN
RHS column wall thickness tc mm
Grade S275 (Grade 43) Grade S355 (Grade 50)
Bolt
diameter
mm
M16
M20
M24
6.3
40
56
67
8
63
81
10
46
65
89
12.5
73
106
5
39
68
68
6.3
86
46
73
8-12.5
106
5
30
46
53
Hollo-Bolt design strengths
Bolt
diameter
mm
M8
M10
M12
M16
M20
Normal design
strength (Pp(n))
kN
16
26
38
70
110
Structural integrity
design strength (Pp(si))
kN
10
17
25
46
73
Table 6
Table 7
Table 8
n rows ofbolts (criticalbolts arethose inthe column)
Tie force
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
12/13
Basic Requirement
Tie force Tying capacity of RHS column
wall
Tying capacity of RHS column wall8 mu
= (1+ 1.5 (1 - 1)0.5 (1 - 1)0.5)(1 - 1)
Mu = moment capacity of RHS
column wall per unit lengthpyctc
2
=4
pyc = design strength of the RHS column
(S275 = 275 N/mm2 : S355 = 355 N/mm2)
tc = thickness of RHS column wall
n1 = (n - 1)p - d
2
(B - 3tc)
g1 =
(B - 3tc)
d1 =
(B - 3tc)
B = overall width of RHS columnwall to which the connection is
made.
d = bolt diameter (or hole diameter
in RHS column for Hollo-Bolt)
g = bolt gauge width
n = number of rows of bolts
p = bolt pitch
Structural integrity - tie forcecapacity of RHS column wall in the
presence of axial compression in the
column.
Note: This check is only needed if it is
necessary to comply with structural
integrity requirements.
tc
1.5 tc
Tie force
(applied at
bolt positions)
Bolt holes
deducted
Yield lines
B
p
g
(n-1)p
8/2/2019 [Corus] SHS Jointing - Flowdrill and Hollo-bolt
13/13
British SteelTubes & Pipes
PO Box 101, Weldon Road,Corby, Northants, NN17 5UA
Tel: 01536 402121Fax: 01536 404111
TD3
84.1
2E.9
5