Straub Flex 1 & Open Flex 1 Coupling

Date Posted:22 August 2025 

Straub® Flex 1 – 48.3–168.3 mm

Straub Flex 1L coupling Straub Flex 1L technical drawing

Flexible, non-restrained coupling for small-diameter plain-end pipes. Installs with a torque wrench; no hot work.

  • Working pressure
    24–64 bar (2,400–6,400 kPa)
  • Temperature
    −20 °C to +100 °C
  • Materials
    316L stainless housing; EPDM/NBR/FKM seals
  • Angular deflection
    Up to 5°

Overview

Compact alternative to expansion joints on smaller pipelines. Allows axial movement and angular deflection. Works on rough pipe surfaces.

Technical specifications

Size range 48.3–168.3 mm
Working pressure 24–64 bar (2,400–6,400 kPa)
Temperature range −20 °C to +100 °C
Housing 316L stainless steel
Seals EPDM (standard), NBR, FKM
Angular deflection Up to 5°
Standards DIN 86128, ASTM 1476
Design life 25+ years

Non-restrained: fixed points/external restraint required.

Applications

  • Water treatment & HVAC
  • Industrial piping
  • Plumbing
  • Marine/offshore

Request a quote

Contact us for current pricing and availability.

Request a quote Email sales@dewaterproducts.com.au

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Coupling Dimensions

Pipe OD (mm) Clamping Range (mm) PS Bar B (mm) C (mm) DV (mm) KV (mm) Pipe Gap w/ Insert (mm) Torque (Nm) Allen Head (mm)
48.3 47.0 – 49.5 25 75 35 70 85 15 7.5 6
54 52.5 – 55.5 25 75 35 76 90 15 7.5 6
57 55.5 – 58.5 25 75 35 79 95 15 7.5 6
60.3 59.0 – 61.5 25 75 35 82 95 15 7.5 6
73 71.5 – 74.5 25 94 51 95 117 25 7.5 6
76.1 74.5 – 77.5 25 94 51 98 122 25 7.5 6
84 82.5 – 85.5 24 94 51 106 127 25 7.5 6
88.9 87.5 – 90.5 24 94 51 111 132 25 7.5 6
100.6 99.0 – 102.5 23 94 51 123 147 25 7.5 6
101.6 100.0 – 103.5 23 94 51 124 147 25 7.5 6
104 102.5 – 105.5 22 94 51 126 147 25 7.5 6
104.8 103.0 – 106.5 22 94 51 127 147 25 7.5 6
108 106.5 – 109.5 22 94 51 130 152 25 7.5 6
114.3 112.5 – 116.0 21 94 51 136 157 25 7.5 6
127 125.0 – 129.0 19 107 62 149 165 35 10 8
129 127.0 – 131.0 18 107 62 151 165 35 10 8
130.2 128.5 – 132.0 18 107 62 152 165 35 10 8
133 131.0 – 135.0 16 107 62 155 170 35 10 8
139.7 138.0 – 141.5 16 107 62 162 175 35 10 8
141.3 139.5 – 143.0 16 107 62 163 180 35 10 8
154 152.0 – 156.0 16 107 62 176 190 35 10 8
159 157.0 – 161.0 16 107 62 181 195 35 10 8
168.3 166.0 – 170.5 16 107 62 190 205 35 10 8

Notes

  • FPM/FKM sealing sleeve also available on request.
  • Always follow fitting and disassembly instructions.
  • PS = working pressure considering application loads.
  • Test pressure = 1.5 × PS.
  • Burst pressure ≈ 2 × PS.
  • Strip inserts are supplied with all couplings sold in Australia.

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