RESTORATIVE HEAT TREATMENT

Restorative Heat Treatment (RHT) — is a set of technological processes and operations aimed at extending the service life of power equipment that has reached the end of its designed operational period.
The purpose of RHT — is to restore the structure and properties of metal that has been in service for an extended period by means of complete phase recrystallization to a state as close as possible to the metal’s original condition.

NOMENCLATURE OF RESTORED EQUIPMENT

The nomenclature of restored equipment includes:

High- and intermediate-pressure turbine cylinder casings
Steam chests of steam distribution units
Casings of stop and control valves
Diaphragm casings
Elements and bends of main steam pipelines

The technology and corresponding equipment for performing restorative heat treatment were successfully tested on Unit No. 1 of the Zmiivska TPP on the stop valve chests of the K-200-130 turbine with a capacity of 200 MW.

We carried out a comprehensive set of works including inspection, repair, renovation, machining, and control testing of the metal in the steam chests after restoration. This enabled the extension of the service life of decommissioned equipment by 80,000 hours.

The list of main operations performed during RHT includes:

research, control samples for non-destructive testing, geometry measurements, and technical condition assessment;
mechanical removal of all cracks on internal and external surfaces;
crack filling by welding with allowance for subsequent machining;
metal structure regeneration — two-stage heat treatment in a furnace; the heat treatment mode is developed individually for each case;
machining to nominal dimensions;
post-repair examinations and issuance of a report.

Restorative heat treatment, as a repair operation, is a full-fledged alternative to the very costly replacement of equipment with new units. When approached professionally and comprehensively, it allows the properties of power equipment components to be restored to a level close to that of new equipment.

Moreover, the RHT process is carried out within a significantly shorter timeframe than the manufacturing of new equipment (3–4 months), and at a much lower cost (up to 40% of the price of new equipment).

Thermal treatment services are provided by a dedicated division of “KHARKOVENERGOREMONT-HOLDING” — the company LLC “HIT-KHAER”.