Garlock Sealing Technologies
GASKET INSTALLATION
and TROUBLESHOOTING
INSTRUCTIONAL PROGRAM
Opening:
Increased environmental controls have made industry standards on gasketing and leakage more critical than ever before.
In realizing this, Garlock has developed the following program detailing the steps through installation and trouble shooting.
The guidelines set forth in this program are not intended to be complete and do not cover every possible condition associated with the safe usage and installation of gasketing products.
The first step to proper installation is understanding the functions of a gasket. A gasket must perform two primary functions:
1. It must create the initial seal,
-and-
2. It must maintain that seal for an extended period of time.
Factors affecting performance:
Consider the elements that affect a gasket's performance (i.e. factors that determine how well a gasket can seal).
· The gasket has to maintain its integrity during handling and installation.
· The gasket must be deformable enough to flow into the imperfections on the sealing surfaces to create an initial seal.
· The gasket must have sufficient strength to resist crushing under the applied load and defy blow out under system pressure.
· The gasket must chemically resist the system fluid and withstand even the highest system temperatures.
· The gasket must be strong enough to maintain its seal, tough enough to withstand creep relaxation and, resilient enough to provide recovery during normal operations, including thermal cycling, vibration and pipe hammering.
· The gasket must never promote corrosion of the sealing surface. It must be impervious to the fluid being sealed. And finally, the gasket should be easy to remove.
The absence of any one of these factors can result in conditions undesirable to any industry. Therefore, it is recommended that these factors be used as a checklist when selecting a gasket for an application.
Tools Required:
Before beginning the installation process, select the proper equipment. This includes:
· a flange spreader,
· soft wedges,
· lubricating oil,
· nuts, bolts, washers and fasteners,
· a metal flange scraper or an aerosol gasket remover,
· a box end type wrench,
· and, a calibrated torque wrench.
This will assure equal bolt loading during the tightening of fasteners. The last item necessary for the installation is the correct gasketing product.
Tips for Selecting Gaskets:
As discussed earlier, gasket selection depends upon many variables. Use the following tips as additional guidelines when choosing the right gasket for your application.
-Whenever possible, we recommend using thinner gaskets. However, flanges that are warped, bowed or severely pitted will require thicker gaskets to compensate for the irregularities. Thicker gaskets require additional compressive loads; these higher loads may or may not be obtainable in your application.
-When possible, use ring gaskets. Full face gaskets normally have twice the number of square inches compared to ring gaskets. This extra material requires added torque which, again, might not be obtainable in your application. However, if each flange face is flat and made from soft material, a full face gasket might be necessary in order to prevent flange rotation.
-Finally, all Garlock compressed non-asbestos gaskets have anti-stick on both sides (except GYLON®, which does not need anti-stick). If you feel it is necessary to add more anti-seize, remember the rule: Dry is always better than wet, so use these products sparingly. We feel talc works best, graphite and mica are also acceptable. Never use metallic based anti-seize. The metallic particles may accumulate in the surface imperfections creating a flange surface that's too smooth to be effective.
Begin the Installation:
· To begin the installation, use wrenches to remove all fasteners from the flanges. This includes all bolts, studs, nuts and washers. Replace any worn, corroded or damaged fasteners.
· Using a flange spreading tool or soft wedges, spread the flanges apart. Be careful to not damage or interfere with the flange seating surfaces.
· Remove the old gasket from both seating surfaces. If necessary, use a metal flange scraper or an aerosol gasket remover to take off all old gasketing material. Clean the flange surfaces with a wire brush.
· Inspect the surfaces to make sure they are free of debris or foreign material. Imperfections such as warpage, large nicks, dents or gouges will affect the gasket's ability to seal.
· If surface damage exists, it may be necessary to remachine the surface until a satisfactory finish is achieved or replace the flange. For sealing effectiveness, flange surface finishes should be either concentric circles or a phonographic groove. For best results, we recommend concentric circles. Acceptable surface finishes, or RMS readings, should range from 125 to 500.
· Next, inspect the gasket that's been chosen for the application. Double check that the gasket has the correct I.D. and O.D. dimensions and is the appropriate thickness. Examine the gasket carefully. Gaskets with cracks, gouges, folds or other surface imperfections should not be used.
· For ease of gasket installation, all fasteners should first be lubricated with an oil and graphite mixture, or other appropriate thread lubricant. Flanges with seating surfaces that are vertical must have at least two fasteners inserted into the bottom holes of the flange.
· Insert the gasket between the flange seating surfaces. Do not use an instrument to push the gasket into place, as this might damage the gasket and affect its sealing ability. Now, carefully remove the flange spreader or soft wedges, this will allow the flanges to come together. Install the remaining lubricated fasteners and secure each until finger-tight.
· The pattern in which the bolts are tightened is extremely important. If done improperly, the tightening can cause the flange to move out of parallel. Refer to your "Garlock Engineered Gasketing Products" catalog to select the appropriate bolting pattern for your application. Using a calibrated torque wrench and a box end type wrench, tighten each fastener in the proper bolting pattern to no more than one-third of the desired torque value. This process will uniformly compress the gasket. Now, repeating the same pattern, increase the torque wrench setting to two-thirds of the desired torque value.
· Achieve the final torque value by repeating the pattern one more time. Examine your work. Using a counter-clockwise sequence, check each fastener with the torque wrench. At this point, each fastener should be applying the same load.
System Start-Up:
After a successful hydrotest and system startup, let the system operate for at least 12 to 24 hours. Thermal expansion, creep relaxation and fastener thread embedment may change the fasteners' applied load. Therefore, it may be necessary to re-check each fastener. This is especially true with gasketed joints that have limited compressive load available. Shut down the system. All applicable safety standards including lockout/tagout procedures should be observed. Using the same counter-clockwise sequence, retorque each fastener with the torque wrench to the desired torque value. Gasketed assemblies sometimes leak during the hydrotest, system startup or during normal operations. If this occurs, check the following conditions:
· Make sure all bolts are at the proper torque value.
· If, after retorquing, the gasketed joint continues to leak, shut down system (observe all applicable lock out/tag procedures), increase the torque setting to 125 percent of the original torque value. Remember to tighten the fastener using the same bolting pattern sequence as before. Re-check your work using the counter-clockwise sequence: each fastener should be applying the same load.
· Finally, examine the gap at the O.D. of the flanges: the flange seating surfaces must be parallel.
· Restart system and bring to operating conditions.
The gasket should now be properly installed and operating at a high performance level.
TROUBLE SHOOTING
If, at any time, a gasketed assembly leaks, begin trouble shooting by shutting down the system.
· Drain off all pressure that's being applied to the joint and remove all bolts, nuts and washers.
· Carefully remove the gasket from the flange; try to keep the gasket intact.
· Now, examine the gasket to determine if it was damaged during the installation; for example, a roll over at the edge onto the seating surface.
· At this time, also look for chemical attack and over compression; two very common reasons for gasket failure.
· Check if an additional anti-stick or anti-seize compound was applied to the seating surfaces of the gasket or the flanges. These materials can lower the performance of the gasketing materials.
· Inspect the seating surfaces of the gasket, (impressions that were left by the flange will help determine what kind of hold the flanges had on the gasket), and if the flanges had the required surface finish.
· Finally, measure the thickness of the gasket all the way around the seating area. This will determine if the gasket was compressed evenly. If the gasket was compressed more towards the OD of the seating area than the ID, flange rotation is occurring.
If these trouble shooting steps are unsuccessful, consult your supervisor or contact your Garlock Representative for help.
Garlock Bolt Torque Tables are available for ANSI flanges. These tables were developed as a guide for installation of our Compressed Sheet, GYLONÒ and Graph-LockÒ gaskets. The thicknesses covered by these tables are 1/32", 1/16" and 1/8".
Note: This information is to be used only as a guide. Should you require additional information on any aspect of gasketing or have any questions, call your Garlock Representative.