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Get Acrobat Reader You will need Acrobat Reader to view pdf Flange Bolt Torquing
for Resistoflex Plastic-Lined Piping Products

The same general techniques used to install flanged carbon steel piping systems can be applied to Resistoflex plastic-lined piping systems.

When assembling flange connections, always use a full complement of clean, new high strength A193-B7 bolting. If using stainless steel bolting, the bolts should be A 320/A 320M Class 2 B8 (304 SS) or Class 2 B8M (316 SS) with A 194/A 194M Grade 8 or 8A Nuts (for 304 SS) or Grade 8M or 8MA (for 316 SS). If other bolting materials are used, the end user must ensure that the new bolting material strength properties exceed the calculated bolt stress values to be generated in making the piping connection.

  • Always use flat washers on both sides of the connection.
  • Tighten the flange bolts with a calibrated torque wrench to the specified bolt torques. Note: For anti-seize compounds, the torque values will be different. Please contact Resistoflex for more information.
  • Tighten the flange bolts with a torque wrench, using a "crisscross" pattern that alternately tightens the bolts located 180 degrees apart.
  • Using this pattern, tighten the bolts in 20% increments of the final bolt torque until 80% of final bolt torque has been achieved.
  • For tightening to the final torque values, tighten bolts sequentially clockwise once around the flange. This will help ensure that the bolts are evenly stressed.
  • Care should be taken to avoid over-torquing, which can cause damage to the plastic sealing surfaces.
Note: When bolting together dissimilar materials, always tighten to the lowest recommended torque of the components in the joint. Using higher torques may cause excessive deformation of the "softer" material in the joint. Install a ½" thick spacer between Resistoflex plastic-lined pipe or fittings and other plastic-lined components, particularly valves, if the diameters of the raised plastic faces are different. Belleville washers are not recommended for use with PTFE-lined products.

Retorquing

A retorque should be applied a minimum of 24 hours after the initial torque or after the first thermal cycle. This allows for seating of the plastic and for relaxation of the bolts. If the system is to perform at elevated temperatures, it is recommended that hot water be circulated at the maximum operating temperature of the process (if possible) for a minimum of 24 hours. This allows for the pipe system to experience one thermal cycle. After cool down, retorquing of the system should be done. Torquing should only be done on the system in the ambient, cooled state, never while the process is at elevated temperature, or excessive force could be applied to the plastic faces. Never disassemble a flange joint in a hot system. Wait until the system has cooled to ambient temperature.

Hydrotesting

Normally, after initial torque and retorque, a hydrotest should be performed following ANSI requirements. Experience has shown that if the above procedure has been followed very few, if any, of the flange joints may fail the hydrotest. If a flange joint does leak, first check the torque values, and then tighten in 10% increments over the specified bolt torques until sealed. However, if 150% of the specified torque value is reached and the flange joint still leaks, stop and disassemble the flange joint. Something else is probably wrong such as a scratched plastic face.

Only after the hydrotest has been successfully completed and any leaks corrected, can the pipeline can be signed off and commissioned.

Annual Retorquing

Retorquing should be done at least annually thereafter, especially if the process line experiences elevated temperatures or extreme ambient temperature situations. Torquing should only be done on the system in the ambient, cooled state, never while the process is at an elevated temperature, as an excessive force will likely be applied to the plastic faces.

Always tighten bolts in crisscross pattern
Convert To English Units
ANSI Class 150 systems
Lightly oiled A193 B7 bolts and A194 2H nuts
Pipe Size
(mm)
Bolt Torque (N-m)
PP PVDF PTFE PFA
Min. Max. Min. Max. Min. Max. Min. Max.
15 -- -- -- -- 9.5 13.5 -- --
20 -- -- -- -- 14.9 21.7 -- --
25 17.6 23.0 23.0 28.5 10.8 17.6 16.3 23.0
40 42.0 55.6 55.6 67.8 25.8 42.0 38.0 55.6
50 88.1 115.2 115.2 141.0 52.9 88.1 80.0 115.2
65 78.6 101.7 --- --- 47.5 61.0 --- ---
80 139.6 181.7 181.7 223.7 84.1 139.6 126.1 181.7
100 90.8 119.3 119.3 146.4 54.2 90.8 82.7 119.3
150 168.1 218.3 218.3 269.8 101.7 168.1 --- ---
200 226.4 294.2 294.2 362.0 135.6 226.4 --- ---
250 212.7 276.6 --- --- 212.7 276.6 --- ---
300 261.7 340.3 --- --- 261.7 340.3 --- ---
*The reason that the 65mm are lower than the 50mm is that the effective gasket area is smaller for this particular pipe size.

ANSI Class 300 systems
Lightly oiled A193 B7 bolts and A194 2H nuts
Pipe Size
(mm)
Bolt Torque (N-m)
PP PVDF PTFE
Min. Max. Min. Max. Min. Max.
25 23.0 29.8 29.8 36.6 13.6 23.0
40 63.7 82.7 82.7 101.7 38.0 63.7
50 44.7 57.0 57.0 70.5 27.1 44.7
80 84.1 108.5 108.5 134.2 50.2 84.1
100 109.8 142.4 142.4 176.3 66.4 109.8
150 112.5 146.4 146.4 179.0 67.8 112.5
200 176.3 229.1 229.1 280.7 105.8 176.3
250 183.0 237.3 --- --- 183.0 237.3
300 252.2 328.1 --- --- 252.2 328.1

Note: These maximum torques are only valid for LIGHTLY OILED A193 B7 bolts. Lightly oiled is considered lubrication with WD-401 or equivalent. Please contact us for guidance on torques for other bolting/lubrication systems.

Note:The maximum recommended torque values are suggested for lined systems operating at or near the maximum recommended pressures and temperatures. Systems operating under less severe conditions can in general experience leak-free performance using lower torque values. Additionally, anytime gaskets or spring type washers are used, we suggest using the minimum recommended torque value and that the torque be increased only to obtain satisfactory sealing. For systems that will require frequent disassembly, we suggest using the minimum recommended torque value initially to avoid distortion of the plastic face.

1WD-40 is a registered trademark of WD-40 Company, San Diego, CA.

ANSI Class 150 systems
PTFE coated A193 B7 bolts and A194 2H nuts
Pipe Size
(mm)
Bolt Torque (N-m)
PP PVDF PTFE
Min. Max. Min. Max. Min. Max.
15 -- -- -- -- 5.4 8.1
20 -- -- -- -- 9.5 12.2
25 10.8 13.6 13.6 17.6 6.8 10.8
40 25.8 33.9 33.9 40.7 15.0 25.8
50 52.9 69.1 69.1 84.1 31.2 52.9
80 84.1 108.5 108.5 134.2 50.2 84.1
100 54.2 71.9 71.9 88.1 32.5 54.2
150 101.7 131.5 131.5 161.3 61.0 101.7
200 135.6 176.3 176.3 216.9 81.3 135.6
250 127.4 166.8 --- --- 127.4 166.8
300 157.3 203.4 --- --- 157.3 203.4

ANSI Class 300 systems
PTFE coated A193 B7 bolts and A194 2H nuts
Pipe Size
(mm)
Bolt Torque (N-m)
PP PVDF PTFE
Min. Max. Min. Max. Min. Max.
25 13.6 17.6 17.6 21.7 8.1 13.6
40 38.0 50.2 50.2 61.0 23.0 38.0
50 27.1 33.9 33.9 42.0 16.3 38.0
80 50.2 65.1 65.1 80.0 29.8 50.2
100 66.4 85.4 85.4 105.8 39.3 66.4
150 67.8 88.1 88.1 107.1 40.7 67.8
200 105.8 136.9 136.9 168.1 63.7 105.8
250 109.8 142.4 --- --- 109.8 142.4
300 151.9 196.6 --- --- 151.9 196.6

ANSI Class 150 systems
Zinc Plated A193 B7 bolts and A194 2H nuts
Pipe Size
(mm)
Bolt Torque (N-m)
PP PVDF PTFE
Min. Max. Min. Max. Min. Max.
25 25.8 33.9 33.9 42.0 16.3 25.8
40 62.4 80.0 80.0 99.0 36.6 62.4
50 127.4 166.8 166.8 204.7 77.3 127.4
80 202.0 263.0 263.0 324.0 122.0 202.0
100 132.9 172.2 172.2 212.9 80.0 132.9
150 244.0 317.3 317.3 390.5 146.4 244.0
200 328.1 425.7 425.7 524.7 196.6 328.1
250 309.1 401.3 --- --- 309.1 401.3
300 379.6 493.5 --- --- 379.6 493.5


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