The VHT series of machines has been designed for wellhead machining applications, such as when gate valves are seized. When this happens, one solution is to fit a new valve on top of the defective one and to machine a hole through the seized slab gate, allowing the product to flow through.
Overview of the VHT Series
The products designed to solve the above problem is a range different sized machines based on the tried and trusted ‘CHT’ high pressure hot tapping machines. In reality, these aren’t ‘true’ hot tapping machines. Essentially, they are a drilling solution, but delivering the same advantages as the CHT range, including the resilience to withstand high pressures up to 5,000 psi and temperatures up to 230⁰c.
An essential feature for a valve hot tapping/drilling machine is to ensure sufficient stroke to reach the slab valve through the wellhead assembly. Mirage offer 5 machine variants; from the VHT965 which has a maximum stroke from 38”, to the VHT4000 which provides a maximum stroke of 160”
The drive that powers the cutter provides high torque transfer and smooth power delivery. The drive unit is positioned close to cutter and the resulting reduction in bar torque gives a smoother cut.
The machine incorporates an auto-feed gearbox and motor with variable feed and manual traverse feature. The manual feed rate delivers 3mm (0.118”) per revolution.
Internal pressure is managed using a balanced system which reduces mechanical shocks and forces when operating at high pressures. The machine also uses constant seal and pressure monitoring, ensuring any pressure leaks can be monitored and contained whilst the machine is in use.
Measuring depth of the cut
The VHT series uses a geared mechanical depth display, providing a much easier solution that reliance on measuring rods. An LCD display can be provided as an option if preferred.
- Find out more about API 6A Gate Valves in our previous infographic article.
- Download the hot tapping machine buyers guide
- If you need advice selecting a machine for an on-site machining project get in touch with your regional contact here