Gasket Installation – Best Practices
The performance of a gasket relies on a number of elements, including:
- Component being sealed
- Flange design
- Type and quality of the material
- How the gasket is installed and tightened onto the flanges
- The volume of pressure applied to the gasket by the bolts
Sometimes, the most basic reason for leakage in bolted couplings is not the gasket’s fault but the human part – incorrect installation. Therefore, maintenance operators, engineers, and fitters should assess all circumstances to authenticate the products are adequate for the intended purpose or process.
Particular equipment is needed for cleaning the flange and tensioning the bolts. It is crucial to always use standard safety equipment and adhere to good safety practices. Below is a list of tools that are needed for removal of an old gasket, and preparing and installation of the new one:
- Brass wire brush
- Personal safety equipment
- Hydraulic tensioner or calibrated torque wrench
- Lubricants for the bolts
- Other equipment determined by the company or manufacturer
Clean and assess flange appearance. Get rid of all debris from the flange surface, nuts, washers and fasteners (bolts and studs). To clean the flange surfaces, use a brass wire brush in the direction of the grooves. Assess the flange appearance, nuts, washers, and also fasteners to make sure they don’t have any severe deficiencies. Replace any elements that are faulty. If uncertain, ask for advice from an expert or your supplier.
Make sure the gasket is the exact size. The gasket’s inner diameter should not be smaller than the flanges’ inner diameter. To solve a problem with a gasket, it is important not to use a thicker gasket material or ‘‘piled gaskets’’. Trim the bolt holes a little larger than the bolts to make it easier to centralize the gasket.
To prevent warping and tensions, gaskets should be stored horizontally. Best storage environment is in a clean space, such as a plastic container at 50-60% humidity, <75°F and not in direct light. All gaskets should be handled with caution. Carry them in a protective cover, protect the surfaces and do not bend (or write!) on the gaskets.
Nuts, Washers & Bolts
Ensure that the correct bolts are used taking into account the intended media temperature. In addition, make sure that there is no deterioration on the bolts – it can affect the performance of the bolt. Do not re-use bolts. Utilise a nut that has a particularised proof load 20% larger than fastener’s utmost strength. It is important to use standard threads instead of fine threads and use an adequate lubricant. Use the same material for the nuts and washers. Also, use the washers to connect oversized or slotted holes, smooth interface forces between joint elements and decrease issues of wear by widening the load forced by the fastener on the joint.
Line up the flange faces and bolt holes and assess all disarrangements. Make sure the gasket is the correct size and material and that it has no defects. Cautiously put the gasket between the dry flange and ensure that the gasket is centralized. It is advised not to use joint elements or release agents on the gasket or flange surfaces as it can cause lower surface friction and gasket loosening. Join the flanges making sure the gasket is not damaged or pinched.
Regularly use lubricant on the nut and bolt threads, and the face of the nut to lessen friction whilst tightening. You must not pollute the flange or gasket surfaces with lubricant. Make sure that the lubricant’s advisable service temperature is within the service temperature limits.
Tightening of the Bolts
Gaskets installed with high compressive stresses demonstrate a larger performance service than gaskets installed with lower media stresses. Firstly, tighten all nuts by hand. Use a calibrated torque wrench in order to accomplish an equal compression of the gasket. Make 3 whole passes each in a crisscross bolt pattern to the demanded torque. Proceed with one last pass, torquing the bolts in a clockwise direction until all torque is the same. Flanges with large diameter may need more passes.
Re-tightening should only be performed at atmospheric pressure, ambient temperature and before or whilst the first start-up. Do not re-tighten compressed fibre gaskets which have been subject to extended or elevated operating temperatures. Re-torque fasteners exposed to aggressive thermal cycling when the joint is at ambient temperature.
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The Gasket Installation Guide is designed to provide a basic overview.
E & OE. M Barnwell Services endeavours to make sure that all content is correct. Information has been gained from manufacturing partners.