Proper Installation of a Bolted Joint Gasket

Written by Jim Drago, P.E., Jim Heffron and Dave Burgess, Garlock Sealing Technologies

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Calculation of Torque

The sealing solution provider should provide practical information to assist the plant in documenting gasket installation and maintenance procedures. A critical component of such documentation is the calculation of the optimal torque applied to the bolts at each joint location.

The bolt torque value will depend on the type of gasket, as well as the size of the pipe, the number and size of the bolts, and the internal pressure.

Installation Recommendations from Garlock

Our engineers have developed a set of best practices for bolted joint gasket installation:

Inspect the flange to ensure that the surface finish and flatness are satisfactory.
Center the gasket on the flange. Careful centering of the gasket is especially important when raised faces are involved. Take care when bringing the flanges together to ensure that the gasket is not pinched or otherwise damaged.
Use a recently-calibrated torque wrench, well-lubricated fasteners and hardened flat washers to ensure correct initial loading.
Lubricate fastener threads and all bearing surfaces (underside of bolt heads, nuts, washers), using only specified or approved lubricants. Apply the lubricant in a consistent manner as a thin, uniform coating (avoid "lumps" of lubricant as this may reduce the efficiency). Ensure lubricant does not contaminate either flange or gasket faces
Run the nuts or bolts down by hand. This gives an indication that the threads are satisfactory (if the nuts will not run down by hand, then there is probably some thread defect-check again and, if necessary, replace defective parts).
Tighten the bolts to compress the gasket uniformly, utilizing a star bolting pattern (see Figure 2). After initially bringing all bolts to snug or finger-tight, all bolts should be tightened in one-third increments at each pass. The sequence in which bolts or studs are tightened has a substantial effect on the distribution of the assembly pressure (compression) on the gasket. Improper bolting may move the flange out of parallel. A gasket will usually be able to compensate for a small amount of distortion of this type, but serious difficulties may emerge if the flanges are substantially out of parallel.
Make a final check pass at the target torque value moving consecutively from bolt to bolt.
Re-torque 12 to 24 hours after initial installation, whenever possible.
Observe all safety standards including lockout/tagout procedures.
Never use liquid or metallic based anti-stick or lubricating compounds on the gaskets. Premature failure could result.

Preventive Maintenance

Best practices also include regular preventive maintenance. Daily or weekly inspections of fluid-handling systems can minimize downtime and allow corrective actions to be taken before irreversible failures occur. Another sound operating practice that can save plants time and money is changing sealing devices on a routine basis to make sure the system is properly equipped.

Consistently following these installation and maintenance recommendations is critical to achieving high performance and long service life with bolted joint gaskets. Proactively preventing leaks in your fluid-handling systems requires diligence and remains a constant struggle if the basics of good installation are not followed. Selecting a high quality, high performance gasket solution wins half the battle. To win the overall battle, consistent and thorough performance and documentation of procedures and system maintenance is a must.

Jim Drago, P.E., is manager, business development, Jim Heffron is senior marketing manager and Dave Burgess is senior applications engineer for Garlock Sealing Technologies, 1666 Division Street, Palmyra, NY 14522, 1-800-448-6688 (315-597-4811), Fax: 1-800-543-0598 (315-597-3216), www.garlock.com.

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