Best Practices:

Flange Preparation:

 ·        Clean flanges using wire brush or flat file.

 ·        When using spray adhesive clean flanges with an evaporating solvent.

 ·        Check flanges for leak paths - mechanical damage - tool marks, dents, nicks, scratches, gouges, cracks, pits, corrosion, and warpage.

·        Gasket surface criteria: roughness 125 rms. + / - 25, warpage 0.010” (total difference between mating flanges), circumferential warpage .020” over 2 feet, negative radial warpage .00, positive radial warpage .012” (max.) 0ver 1-1/4” gasket surface.

·        Flange face damage: machine surface if minimum thickness permits.  Weld build if flange is at or below minimum thickness. * Consult Materials Engineer on welding and heat treatment requirements.

Installation Procedures:

·        Inspect the gasket, check for defects and shipping or storage damage. Large diameter gaskets have seams due to raw material size limitations. Graphite faced gaskets have tapped seams that are self-healing when flange loads are applied.

Assembly:

Bolt loads:

·        50-60,000 psi recommended.

Gasket stress:

·        5,000 minimums recommended.

 ·        For male and female or tongue and groove flanges, the gasket should be installed in the center of the groove.

 ·        Do not use grease or anti seize type lubricants on the flange or gasket faces.

 ·        For gaskets that need to be held in place during installation lightly apply just enough 3M Super or equivalent spray adhesive to hold the gasket in place.

·        Install new lubricated bolts with lubricated case hardened washers under new nuts.  The bolt threads and nut contact surfaces should be lubricated with a lubricant that is compatible with the service and temperature.

·        Number the bolts for sequence tightening using the Bolting Patterns (Tightening Sequence) to facilitate the tightening order.  If the correct tightening sequence is not followed, the flanges can be misaligned, making it impossible to have a uniform seating of the gasket.

Bolt tightening:

 ·        Insure proper flange mating and fit with a uniform gap. Observe the gap in each step for uniformity.

·        Tighten bolts in the sequential order following Compression Bolting Patterns (Tightening Sequence) applying 30% of the final torque using a calibrated, clicker type torque wrench or similar tension control method.

 ·        Repeat the above step elevating the torque to 60% of the final torque; continue tightening in the recommended sequence until 100% of the value is reached.

 ·        The same bolts normally have to be tightened more than once. Chase the final load in a rotational order until all bolts reach the target stress.

·        Hot torque the connection when it is between 200 - 300 degrees F. *

* When the flange is too hot to touch. Warning:  DO NOT HOT TORQUE FLANGES UNDER PRESSURE.

 Alternative bolt tightening - Fast Method.

 ·        Install all bolts.

·        Tighten 8 bolts (#’s 1-8) to 30% of final load.

 ·        Tighten 8 more bolts (#’s 9-16) to 60-70% of final load.

 ·        Tighten 8 more bolts (#’s 17-24) to 100% of final load.

 ·        Tighten all bolts to 100% of load in circular pattern or until the nuts no longer turn.

·        Go around the connection one more time and tighten to 100% of the final load in a circular pattern.

  n      Compensates for stud cross talk.

n      Verifies all studs evenly torqued to 100% of target load.

 ·        Hot torque the connection when it is between 200 - 300 degrees F. *

* When the flange is too hot to touch.  DO NOT HOT TORQUE FLANGES UNDER PRESSURE.