Introduction

The torque figures for ACL® Clamps are
based on the following assumptions:

  • The torque values given are for the common sanitary union design.
  • Torque figures are based on maintaining ASME-BPE SG-4.2 CAT II Intrusion.
  • The figures are based on the maximum working pressure (MAWP).
  • Ferrules and gaskets must conform to recognised industry standards and enable the correct assembly of the union with minimal gasket crevices.
  • Polymeric gasket unions should be re-torqued after allowing some time for the gasket to creep.
  • The torque figure can be reduced if the MAWP is reduced and ASME BPE categories of intrusion are adhered to. However, a minimum of 2Nm should be considered.
  • Torque is applied in a slow and steady manner up to the required figure.
  • A suitable sanitary lubricant must be used for threads on unions where PTFE is the seal material.

ACL® Clamps use a variety of thread sizes which have been selected for the clamping force requirement of each size and style of clamp.

Table 1. ACL® Clamp Bolt Sizes by Size and Type

Nominal Size
(inches)
SHSSHASME VIIIS-Type
0.55/16” UNC – 18M8 x 1.255/16” UNC – 18
DN105/16” UNC – 18M8 x 1.255/16” UNC – 18
1.55/16” UNC – 18M8 x 1.251/2″ UNC – 135/16” UNC – 18
25/16” UNC – 18M8 x 1.251/2″ UNC – 135/16” UNC – 18
2.55/16” UNC – 18M8 x 1.255/16” UNC – 18
35/16” UNC – 18M8 x 1.251/2″ UNC – 135/16” UNC – 18
3.55/16” UNC – 18M8 x 1.255/16” UNC – 18
45/16” UNC – 18M8 x 1.251/2″ UNC – 135/16” UNC – 18
4.55/16” UNC – 18M8 x 1.255/16” UNC – 18
55/16” UNC – 18M12 x 1.75
5.5M10 x 1.5M12 x 1.75
6M10 x 1.5M12 x 1.751/2″ UNC – 135/16” UNC – 18
6.625M10 x 1.5M12 x 1.75
8M10 x 1.5M12 x 1.751/2″ UNC – 13
8.625M10 x 1.5M12 x 1.751/2″ UNC – 13
10M10 x 1.51/2″ UNC – 13
10.625M10 x 1.5
12M10 x 1.51/2″ UNC – 13
12.625M10 x 1.5

Table 2. Maximum Torque Figures for Standard ACL® Clamp Threaded Fasteners

Maximum Torque Values  
Bolt SizeNm (Dry)Nm (Lubricated)
5/16″ UNC – 1811.210.05
M8 x 1.2521.5719.09
M10 x 1.542.1737.85
M12 x 1.7573.5565.08
1/2″ UNC92.783.15

Table 3. Torque Conversion Factors

 SI Units Imperial Units  Metric Units 
Units to be convertedcN.mN.mozf.inlbf.inlbf.ftkgf.cmkgf.m
1cN.m =10.011.4160.0880.0070.1020.001
1 N.m =10011.4168.8510.73810.200.102
1ozf.in =0.7060.00710.06250.0050.0720.0007
1lbf.in =11.30.1131610.0831.1520.0115
1lbf.ft =135.61.35619212113.830.138
1kgf.cm =9.8070.09813.890.8680.07210.01
1kgf.m =980.79.807138986.87.2331001

Seals and Lubrication

Sanitary elastomeric seals have very good sealing capabilities and seal at a low clamping force. PTFE does not have these characteristics and the material  creep even at low temperatures results in a decreased clamping force on the gasket which can produce a leak at a low pressure.

Lubrication has a noticeable effect on the pressure holding capability of the clamp unions, specifically when polymeric gaskets are used. Also, when the  bolts are unlubricated there is an increased possibility that the threads will gall.

Lubricated clamp loads are 46% higher than dry loads. This will allow for   higher force to be imparted onto the polymeric gasket, thus resulting in a more reliable seal.

For instance:

  • A ½” UNC bolt lubricated and tightened to 83.15Nm will apply a clamping load of 1448 Kg. This load will utilise 90% of the bolt yield strength.
  • A ½” UNC bolt un-lubricated and tightened to 92.7Nm will apply a clamping load of 772 Kg. This load will utilise 40% of the bolt yield strength.

In addition to this; as the torque figure is increased, the chances of galling and failure of the eyebolt at the thread root increase. In order to ensure a better lifetime for your acl clamp, torque should be minimised to the correct level.

In the event that lubrication cannot be applied to the threads, a suitable bolt /nut material combination should be employed. The standard material for this application would normally be Nitronic 60 (Ref. ACL® Anti-Gall).

All technical information and advice given here is based on our previous experiences and/or test results. We give this information to the best of our  knowledge, but assume no legal responsibility. Customers are asked to check the suitability and usability in the specific application, since the performance of the product can only be judged when all necessary operating data are available. Specifications are subject to change without notice. ACL’s terms and conditions of sale apply to the purchase and sale of the product.

Table 4. ACL® Clamp Torque Values – Elastomeric (Dry)

  SH SSH ASME VIII S-Type 
Nominal Size (inches)Flange
Size
MAWPTorque (Nm)MAWPTorque (Nm)MAWPTorque (Nm)MAWPTorque (Nm)
0.525502752252
DN1034502752252
1.550.55027521672252
264502752902252
2.577.5502752252
391403603903203
3.5106403603203
4119353533573173
4.5130304454154
5144.4304454284
5.5155304454
6167305454224154
6.625183255385225
8217.4205306156
8.625233.5206306126
10268.1168108
10.625286.1168
123191010710
12.6253381010

Note: Torque values for elastomeric union seals are given as a dry value. The torque value can be
kept to a minimum as elastomeric seals are self-energising. In the event that a seal is not achieved,
lubrication should be applied to the bolt or a higher torque should be used (do not exceed maximum
torque values shown in Table 2).

Table 5. ACL® Clamp Torque Values – Polymeric (Lubricated)

  SH SSH ASME VIII S-Type 
Nominal Size (inches)Flange
Size
MAWPTorque (Nm)MAWPTorque (Nm)MAWPTorque (Nm)MAWPTorque (Nm)
0.525506756256
DN1034506756256
1.550.550675616710256
2645067569010256
2.577.5506756256
3914096099015209
3.5106409609209
41193595395715179
4.5130301045121010
5144.4301045202820
5.515530164520
6167302045202220710
6.625183252038252225
8217.4202030301524
8.625233.5202430301224
10268.116321032
10.625286.11632
123191037.5740
12.6253381037.5

Note: Torque values for polymeric union seals are given as a lubricated value. In the event that a seal
is not achieved, lubrication should be re-applied to the bolt or a higher torque should be used (do not
exceed maximum torque values shown in Table 2).