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How choosing the correct gasket reduces risks

Health and Safety across any industry are vital, especially so in industrial facilities and settings.  Why?  Because harmful leaks and emissions must be avoided at all costs to avoid serious accidents or injury to your teams and property.  That’s why having the right...

How to tighten your bolts perfectly

How to tighten your bolts and which tools you should use to achieve the perfect seal is not as seamless and straightforward as we would like. Various factors come into play in these situations, such as bolt grade, size, and even application type.  Tightening torques...

Static and Dynamic o rings

A range of factors and application dynamics come into play when choosing a particular type of o ring.  You need to understand the type of seal exert you require, the dimensions, and even compounds.  Due to the nature of an o ring and its overall design, o rings use...

Gasket Sealants

Fortunately, no one gasket suits a range of applications, but rather we have a multitude of gasket sealants available to meet various specifications and requirements.  Ultimately, sealants are used to effectively ensure gasket seals.  Helping to extend a gasket's life...

Types of industrial gasket material

Different industry sectors will use different types of gaskets and different types of gasket materials.   And of course!  Different industrial gasket materials will be much better suited to some industrial processes and applications compared to others.  As different...

Keeping a close eye on the gaskets your applications use

Gaskets are vital elements to any piping system and application that requires creating the perfect seal in order to prevent leaks.  This is the main role of a gasket, to provide a good seal, with some gasket materials sealing better than others in certain...

O Ring Colour Identification

O rings come in various colours, and it's important to understand what these colours indicate as the o rings you choose will affect your overall process application.  Ultimately, different o ring colours are used to help differentiate between different materials. ...

Spiral Wound Gasket Compressibility and Pressure Ratings

In order to form a reliable seal, spiral wound gaskets do require a certain degree of pressure.   The applied pressure allows the gasket to be compressed tightly between the mating surfaces preventing any leaks from occurring.  Factors such as operating temperature...

Elastomeric Compounds

What is elastomer?  Elastomeric compounds are rubber seals produced using natural rubbers or manufactured by the chemicals industry.  Elastomeric sealing compounds consist of between 50-60% rubber; the remainder of the compound consists of fillers,...

Is there such a thing as the right flange gasket?

We cannot stress enough how important gaskets and seals can be. Gaskets are vital for an application's reliability and integrity, and trust us when we say, choosing the right gasket now can help you avoid costly issues in the future.  Taking a closer look at pipe...

How to tighten your bolts perfectly

How to tighten your bolts perfectlyHow to tighten your bolts and which tools you should use to achieve the perfect seal is not as seamless and straightforward as we would like. Various factors come into play in these situations, such as bolt grade, size, and even application type. 

Tightening torques in this sense can therefore become a minefield.   

However, it remains vital to determine the optimum tightening torque for each application as every bolted joint is unique. 

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Bolt tensioning safety is crucial – but what is torque? 

Torque is a rotating force measuring force multiplied by distance. Where distance equals the length of the wrench, and the force is the force you apply. 

What does a correctly tightened bolt look like? 

When a gasket spiral is tightened correctly, it will stretch like a rigid spring, connecting two surfaces securely and as long as the two loads do not exceed each other, then the components/two mating surfaces will not pull apart. 

As you continue to rotate the bolt, the stretching and tightening will continue; however, how much tension you require depends on several factors. 

  1. Bolt diameter is an important area to acknowledge as it will take more force to tighten a ¾ – 10 bolt compared to a 318-16 bolt.
  2. Bolt grade– depending on the material’s strength, it will take more force to stretch an SAE Grade 8 bolt than it does to stretch an SAE Grade 5, for example.
  3. Nut factor– also known as the friction coefficient, this element considers the bolting surface, i.e., those that are hard, smooth, and sleek require less torque than those that are softer, rougher, and stickier.

Taking these factors into account and combined will allow you to opt for the correct torque tightening level. 

Note:  The torque tightening value is only valid if all the application aspects remain constant, and each application should be evaluated on its own to determine the optimum torque value. 

Determining the required torque 

This, as we’ve mentioned, does depend on the spiral wound gasket’s material properties and its overall purpose. 

However, we know that achieving proper torque is essential as if they are under torqued, bolts will deform and won’t provide a solid clamping force. Alternatively, an over-torqued bolt will simply break and give no protection. 

The bolt tightening sequence 

As the most well-known and common sequence, a Star pattern is typically applied to all types of gasket materials, particularly to spiral wound gaskets UK. 

This sequence is then applied when torquing a bolted flange in assembly. 

Of course, gasket type, arrangement of flange connections, etc., still all determine which tightening sequence will be most suitable (we’ll look at some others later in this post). 

Ultimately, the aim is not to damage the gasket in the process of torquing. 

The Star procedure 

Following a star pattern, each flange bolt goes through a process of tightening, which starts at applying between 20-30% force, and then following the same pattern again going over these bolts applying 50-7-% force value, before finally using a rotational pass, stopping when the bolt stops turning.  For spiral wound gaskets, typically two passes will be required to ensure optimum torque. 

Other sequences to note: 

Modified star bolting pattern – an advance on the original star pattern, this sequence is much quicker when you’re working with applications with 20+ bolts; however, it still follows the same star sequence moving from one bolt to the next, applying varying levels of force value. 

Quadrant pattern – a more structured sequencing approach, the quadrant sequence avoids the crisscrossing, moving instead a bolt over only after you’ve completed the first sequence. 

Circular pattern – this sequence is suitable only for solid/hard gaskets such as Kammprofiles, making this sequence unsuitable for spiral wound gaskets. 

As the leading supplier of Spiral Wound Gaskets in Leeds, we carry a large stock volume when it comes to gaskets and bolts. To find out more, make sure to check out our pages online or call us on 01535 274 776; we’d be happy to help. 

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Reference video: Nord-Lock Group

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