Prevent Downtime Caused by Gasket Failure

Downtime in a chemical processing plant has been estimated to cost $500,000 per day or more, so discovering the root cause prior to gasket failure is worthwhile. Increasingly, the potential for failure may be diminished by giving these high consequence devices some attention.

This photo exposes a classic example of damage caused by gasket failure. Once the gasket started leaking, mechanics tried to fix the leak by tightening the clamps. The overtightened clamps exerted force in excess of the fracture point of glass and the glass was crushed on the flange face. The resultant damage propagated into this distillation column. GTI technicians went on site and installed a tantalum patch – total cost over $10,000. Read more about this repair 

Flange with extensive damage

Flange with extensive damage

 

The causes of gasket failure vary. Our field experience indicates almost half of failed gaskets were due to improper loading through seized clamps or improper torque load. The second most frequent cause is improper shimming.

Other common causes include:

  • Erosion, permeation
  • insufficient load from improper installation
  • misalignment of the gasket
  • misaligned flanges and improper loading
  • improper application and/or bolt selection

Use a tabbed gasket on manway covers to prevent damage from repeated opening and closing. This maintains position of the gasket so it does not decompress and cause leaks in the future.

With regard to gasket installation, use of torque wrenches or other controlled tightening methods can help assure that proper load is achieved and evenly distributed on the flange. Most technicians use torque wrenches only on what they consider to be critical applications, but even the most benign processes can cause serious problems. See our table below for recommended torque.

Gasket Size Bolt No. Bolt Size Lubricated Torque (ft lb)
1 1/2″ (4) 1/2″ 20-30
2″ (4) 5/8″ 30-60
3″ (4) 5/8″ 40-70
4″ (8) 5/8″ 40-70
6″ (8) 3/4″ 55-100
8″ (8) 3/4″ 55-110
10″ (12) 7/8″ 60-150
12″ (12) 7/8″ 60-150

 

J-Bolt Lubricated Torque (ft lb)
3/4′ 50-75
7/8′ 85-110
1′ 120-18-
1 1/8′ 170-235

Retighten the bolts after one heat cycle. Call for information on the number of clamps per flange. Gasket shimming information is also available. All glass lined flanges should be checked for shimming between flange faces.

Gaskets for use on glass lined steel applications are specifically designed for the uneven glass on the flange face. This is an important factor and our CRT gaskets are designed for 40% compressibility with 20% memory. Gaskets larger than 18″ are 7/16″ thick to include an additional compressible insert for shimming or additional cushion.

With our standard gasket the 100% virgin PTFE envelope is spark tested to ensure no pinholes exist. The inserts are designed for 40% compressibility with 20% memory. The corrugated stainless steel insert provides rigidity and support for the gasket.  Gaskets are available through 18” diameter in 5/16” thickness

 Our channel gaskets are designed for use in glass lined pipe and nozzles to prevent retention of product. These gaskets are less prone to split. The 100% virgin PTFE envelop is spark tested to ensure no pinholes exist. These gaskets are rated 150 psi at 500F. The compressible inserts are designed for 40% compressibility with 25% memory. Standard thickness is 5/16”.
Standard CRT Gasket

Standard CRT Gasket

 

 Our Pharma gaskets are for use on nozzles, manways and large openings since they are less prone to split. The 100% virgin PTFE envelop is spark tested to ensure that no pinholes exist. These gaskets are rated 150 psi at 500F. The compressible inserts are designed for 40% compressibility with 25% memory. Standard thickness is 5/16”. Larger size gaskets are shipped with an extra insert for overall size of 7/16”. This insert can be used for shimming nozzles as well as an extra 1/8”.
U-gasket

Channel gasket. Dashed lines are corrugated metal which provides rigidity. Gray padding lines at 1/8″ Arimide compressible insert. Black lines are teflon. Overall thickness is 5/16″

 

The best way to prevent costly joint failures is to match the gasket with the application and install it properly while carefully following the manufacturer’s recommended procedures.