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How to conduct Hot Bolting when a Spectacle Blind is Installed.

What is Hot Bolting?


Hot bolting is a method for changing out bolts on piping flanges whilst the process piping remains fully or partially pressurised. It is also known as single stud replacement, line bolting or bolt replacement.


Is Hot Bolting safe?


Hot bolting is safe if you identify and mitigate the risks to personnel, the environment and the asset. The risks include temperature, pressure, process medium, flange condition, work access, etc.


BoltEx installed on a flange after hot bolting

Why would the width of a flange connection vary?


BoltEx® is designed for standard ASME flange connections with standard gasket types, such as those found in RF and RTJ flanges.


However, bolted flange connections often contain other process elements, such as spectacle blinds and orifice flow plates. These elements sit between the flange connection and two gaskets, making the overall connection wider.


In this case, a standard BoltEx® alone cannot be used as the Gasket Protection System (GPS) hollow spacers are not long enough to accommodate the broader gap between the flange faces.



A bolted flange connection with a spectacle blind

How does BoltEx® accommodate flanges that include other process elements?


At SRJ, we have designed extension kits to allow the BoltEx® GPS hollow spacers to span the additional process device between the flange faces. These extension kits enable an expansion of the range over which the GPS are effective.


The extension kits are a simple addition to the setup of BoltEx® and, combined with longer studbolts, provide precisely the same flange security when carrying out hot bolting.



Detail of the BoltEx hot bolting flange clamp with extension pieces

How does BoltEx® accommodate Spectacle Blinds?


The 4-bolt BoltEx® units have been designed to allow spectacle blinds that pivot on the flange bolt to fit between the BoltEx® bolts and clear the BoltEx® unit.


This design feature enables hot bolting to be undertaken on flanges containing spectacle blinds like any other flange connection.


The image below shows BoltEx® installed on a flange with a spectacle blind in place. The standard GPS hollow spacers are shown in dark blue, and the extension pieces are shown in yellow.


The spectacle blind can be seen protruding between the two faces of the BoltEx® and between the BoltEx® securing bolts. Upon removal of BoltEx® after hot bolting is complete, the spectacle blind remains undisturbed.


The BoltEx hot bolting flange clamp on a flange connection with a spectacle blind.

Do Extension Kits come included with BoltEx®?


Not every user will require extension kits to carry out hot bolting, so they are sold separately as an accessory to BoltEx®.


Each extension kit comes compatible with all the BoltEx® units of the same bolt diameter across the range from ½” up to 1¼“. The range consists of 7 extension kits covering all 34 BoltEx® unit types.



BoltEx hot bolting flange clamp extension kits

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