Forging Versus Castings, why we Forge our own valve bodies

Introduction
The worldwide introduction of wind, solar power and other renewables create an increasingly flexible demand on gas fired power stations to balance the grid.

To operate in a reliable, quick, modulating and start/stop regime, some improvements are necessary.

To start and to stop a modern CCGT installation takes time and cannot be done instantaneously.

The gas turbine needs to be warmed through as well as the rest of the power plant, the HRSG, (Heat Recovery Steam Generator) downstream of the gas turbine, the interconnecting steam pipework, the steam turbine and all other balance of plant items.

This all must be done as quickly as possible to limit the starting costs and to supply as soon as possible to the grid.

In the European markets the driving factor is high fuel costs, reducing the need for full speed no load, however in the USA the driving factor is to reach emission values as soon as possible.

For all CCGT plants the demand for being reliable and the need to be able to start the installation, to supply to the grid, is the single most important driving factor.

The AVS Solution
Advanced Valve Solutions has a bespoke package of dedicated products to solve these problems, based on our specific and extensive experience in these types of operating regimes.

With this package in place, it leads to reduced maintenance costs, to reduce starting time and to upgrade the reliability of you existing installation.

With many years of experience and a group of high qualified European manufactures supporting our performance, we deliver a complete solution.

Forging Vs Casting:
The vast amount of valves today are manufactured via casting, however Persta believed a Forged body is the solution for the market.

This Bodies are forged in house, with only the highest quality materials and processes.

Due the fact all forgings are produced in house, the high standards expected from our customers can be delivered and monitored from start to finish.

While castings are the standard form of valve body production, and allow larger products to be produced, there is greater scope for imperfections and inclusions within the casting process. These imperfections can lead to failures further down the lifecycle of the valve.

The nature of forging excludes the occurrence of porosity, shrinkage, cavities and cold pour issues as seen in the casting process as mentioned above.

Forging offers uniformity of composition and structure. Forging results in metallurgical recrystalisation and grain refinement as a result of the thermal cycle and deformation process.

This strengthens the resulting steel product particularly in terms of impact and shear strength.

Forged steel is generally stronger and more reliable than castings and plate steel due to the fact that the grain flows of the steel are altered, conforming to the shape of the part.

With this in mind, for thermal cycling plants, the thinner materials will allow for faster start ups and shutdowns, which results in less thermal stresses in materials.

A forged valve can be made much thinner and stronger, allowing for this demand in stop start operation that we are seeing today.

Tel: 01270 586 944
Email: info@advancedvalvesolutions.co.uk
Web: www.advancedvalvesolutions.co.uk

Published: 15th May 2020