Equipment for local and volumetric PWHT (heat treatment of welded joints)

We performed local heat treatment of steam generator at Atommash

27.08.2020 09:35:00

Heat treatment of welded joints of steam generators at NPP

In Volgodonsk branch of JSC "AEM-technologies" "Atommash" (part of machine-building division of Rosatom-Atomenergomash) seccessed local heat treatment of steam generator bottom weld for NPP "Rooppur".

First, pre-welding of steam generator bottom. Local heat treatment is required operation for stress relief of welded joint. Volume heat treatment in oven is impossible because of built-in thin-walled stainless heat exchange tubes.

Joint is covered by ceramic mats, thermocouples during local heat treatment. Then heating elements heats up to 620-660 degrees. Specialists regulate temperature of 12 heating zones of joint. Temperature is controled every 30 minutes. Difference between thermocouple must be less then 40 degrees.

Local heat treatment includes besides heating of joint and smooth cooling. The process continues 1.5-2 days.

Then steam generator needs to be tested: vacuum and helium tests, and eddy current control of heat exchange tubes.

Steam generator - heat exchange apparatus, part of reactor. It refers to units of first safe class. Apparatus is about 14 meters along, diameter is more then 4 meters, weight - 350 ton. One power unit of NPP consist of 4 steam generators.

NPP "Rooppur" designes and builds by russian project. Plant consist of 2 power units of 1200 MWt with VVER reactors 3+ generation.

This information is posted at official website of JSC "AEM-technologies" and at other side resorces.

Units for performing of welded joints local heat treatment have been delivered by our "Repair technologies" company.

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