Most leaks are not caused by gasket failures but by installation errors. See below for best practices on how to properly install a gasket.
The importance of proper gasket installation cannot be stressed enough. The following is a basic explanation of how to properly bring the flanges together parallel and in stages, once the gasket is in place to properly compress the gasket. As a minimum, four passes are required. Using the right torque value for the lubricant being used to get the proper gasket compression is important as well.
In the torque tables that follow for Durlon® non-asbestos gasket materials, it is assumed the flanges are in good condition, anti-seize has not been used on any gasket contact surfaces and a proper installation technique such as what is outlined below is used. Never use any sheet gasket material as insulating washers in flange insulation kits.
NOTE: As a general rule, soft gaskets are intended for service in Class 300 and below. For applications above Class 300 consult your representative.
HOW TO PROPERLY INSTALL A GASKET
(download installation PDF)
- Be sure system is at ambient temperature and depressurized. Follow local safety rules.
- Visually examine and clean flanges, bolts, nuts and washers. Replace components if necessary.
- Lubricate bolts, nuts, and nut bearing surfaces. Use of hardened steel washers are recommended.
- Install new gasket. DO NOT REUSE OLD GASKET, OR USE MULTIPLE GASKETS.
- Number bolts in cross-pattern sequence according to the appropriate sketch below.
- IMPORTANT! HAND TIGHTEN NUTS, then using a hand wrench SNUG BOLTS 1/8 to 1/4 turn, following the appropriate cross pattern tightening sequence for the number of bolts below.
- Starting at the #1 bolt, use the appropriate cross-pattern tightening sequence in the sketch below for Rounds 1, 2, and 3 (each sequence constitutes a “Round”).
- Final Torque: _________ft-lbs
LUBRICATE, HAND TIGHTEN, PRE-TIGHTEN BOLTS
- Round 1 – Tighten to _________ft-lbs – 1st torque value in torque chart* (30% of final torque)
- Round 2 – Tighten to _________ft-lbs – 2nd torque value in torque chart (60% of final torque)
- Round 3 – Tighten to _________ft-lbs – Final torque value in torque chart (100% of final torque)
* Refer to torque chart by clicking here
Rotational Round – 100% of Final Torque (same as Round 3). Use ROTATIONAL, clockwise tightening sequence, starting with Bolt No. 1, for at least two complete rounds and continue until no further nut rotation occurs at 100% of the Final Torque value for any nut.
Retorque – Short-term bolt preload loss can occur between four to twenty-four hours after initial tightening due to bolt relaxation and/or gasket creep. Repeating the Rotational Round recovers this loss. This is especially important for PTFE gaskets.
TIGHTENING METHODS:
- Hand Wrench
- Manual Torque Wrench
- Hydraulic Torque Wrench
- Impact Wrench
- Other
For torque questions, or tightening patterns for large diameter flanges, contact our Technical Services: 281-380-3548, or tech@durlon.com