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Machining valve seats with a valve boring machine

Posted by Alan Hillier on Jun 8, 2016 4:00:00 PM


    

 

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Machining valves used in the energy sector

Replacing faulty valves in the oil, gas and power generation industries can be very expensive and difficult to carry out. This is not only because of the expense of replacement parts and the manpower needed, but decreased plant availability has significant cost implications.

One example illustrating this is the use of main steam isolation valves (MSIV), commonly used in the nuclear industry. Malfunction of these valves can lead to significant operational disruption including spurious reactor trips, steam generator dry out and excessive valve seat leakage.

In many situations replacement may seem to be the most obvious solution, but this isn’t the only option, as many valves can be refurbished in-situ using a valve boring machine. One Mirage customer needed to remove and refurbish a valve seat within a steam valve. Previously this was not possible because of the position of the valve seat situated very deep within the valve. The problem was overcome by the Mirage design team who developed the VB650 specifically to meet this and other valve boring needs. The features and benefits of Mirage valve boring machines are as follows;

Valve boring machine features and benefits

  • Machines provided with a selection of facing tools, facing heads, extension tool post, boring head and boring bar.
  • Capable of boring and facing operations.
  • Helical geared spindle drive.
  • Maximum stroke up to 17” (extensions also available).
  • Hard chrome boring column.
  • 4 jaw quick set base.
  • Pneumatic and hydraulically powered versions available.
  • Lateral, vertical and column adjustment.
  • Large base plate supplied as standard, (a smaller base plate is available as an optional extra).
  • Down feed and up feed travel direction.
  • Feed options that include an infinitely variable automatic feed rates from 0 to 51mm per minute and a hand crank with a feed rate of 2mm per revolution.

Download the Power Generation Case Study Pack

 

Valve boring machine set up

Taking the smaller machine in the valve boring range as an example, the VB200 set up process is as follows;

  • First of all, a large diameter base plate (supplied with the machine) is bolted directly to the valve. If bolting is not possible, the plate can be secured using ‘G’ clamps or something similar.
  • Next, the machine’s mounting plate is attached to the base plate. This uses a 4 jaw quick set arrangement, providing lateral and vertical adjustment carried out in conjunction with a dial gauge.
  • Before starting the valve boring machine the operator should check that all clamps and tools are tight and that the working area is clear and free from debris.
  • To operate the hand feed the operator simply moves a knob outwards to disengage the auto feed.
  • Direction of travel is set by using the selector switch on top of the motor gearbox.

Valve boring conversion kit

In certain cases, it may not be absolutely necessary to invest in a valve boring machine. Customers currently using the MM600e Flange Facing Machine can order a kit to convert the flange facer into a valve boring machine. Details of the conversion kit can be found here.

To find out more about Mirage valve boring machines please get in touch with us here You may also wish to download our Power Generation Case Study Pack.

Topics: On-site machining, valves, portable machining

   

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