reaction turbine overhaul - part two

Let's start with the glands overhaul.
The overhaul scope was not so large.
- cleaning by blasting,
- NDT examination,
- dowel pins and screws exchange,
- seal strips exchange,
- machining,

This turbine includes 3 glands. Two of them as a external ones and one as an internal one beetwen HP and IP turbine's part.
After blasting our NDT inspectors found no important defects, means no removing and welding works before next steps.
Prior to new pins machining, the pinholes were reamed to get right geometry of the holes, than turner got diameters included proper clearance - I do not remember, but for sure not more than 0.10 mm.
To remove and put new seal strips was the most labour-consuming task. We used vertical lathe to remove old strips and correct the shape/geometry the grooves but anyway it required to be very carefull. Certainly, producing new gland, especially by CNC machines is easier and faster.
Very important thing is worth mentioning - gland setting on the lathe. This activity is one of the most important steps during any machining of used turbine parts. All of them, because of high tempeature, and steam preassure have some deformation even if they were round with accuracy of 0.01 mm as new ones.
Very often detail setting on lathe,boring machine or miller takes hours particullary if they are large but machining itself can last minutes - it is feature of turbine repair...

Hello,
I realize, that for somebody out of power industry service, can be hard to understand what I have here - technical details, I mean .
I am not going to explain just now all the issues but I will try to include some description or even publish posts clarifying more questions regarding structure of turbines

reaction turbine overhaul - part one

In my previous post I mentioned about reaction turbine overhaul projects I supervised in our workshop.
We repaired following parts of this turbine:
- rotor,
- upper outer casing,
- bearings,
- glands,
- internal casings (carriers - is it right technical word?) with stationary blades,

Like usually, the first step before any activity is to take a pictures of parts. It will be an evidence of parts conditions and ( in case when customer does not have documentation) helpfull in further overhaul steps.
The next move is cleaning/blasting and just now we eneter to this moment, which can affect the rest - NDT examination.
This step discovers the real condition of parts. All craks, defects will be found and decision what to do with them will be taken.
In overhaul, describing by me, we had a problem with one of internal casings (carrier).
We found that blade shrounds are not fixed to the blades.
Please see the photos of casing (carrier) no 1

It would be very dangerous to leave it as it is and against technical routines we follow.
Neither we nor customer did not expect such suprise so it was necessary to organize meeting and inform what we found and what are our proposals.
The best way to repair the shrounds would be to exchange the blades into the new ones and put new shrounds as well, but not in this case, as
1. customer was not prepared for such cost,
2. there is no time to carry out this - they need power and steam, so there is a must to fix the issue as fast as possible using enough appropriate technical solution to launch the machine and operate it for some time period.

After the meeting it was decided to applied our proposal - to weld the end of blade - tenon with the shround. This emergency repair will let customer to operate turbine till to next year when wider scope of overhaul has to be taken into consideration.
The repair idea given by my senior management was drew by me and below we have more detailed drawings.

We suspected what are the steels used to manufacture the blade and the shround - each OEM uses the same group of steel but to be sure in 100% the analysys was done. It was especially important for our welding engineers - to define and apply right welding technology. A few welding samples were made to precise post weld heat treatment as weld hardness after PWHT should be proper one. We managed to reach right parameters.

If major overhaul takes place, like we adviced, in 2010 I will have possibilty to check results of this emergency repair - it will be great issue.

Hello,
I have decided to launch my own blog. What for, you can ask... ok, a few words of explanation are needed.
I have taken part in huge amount of overhaul projects during my job and even before, when I was a student. Just now, trying to refresh my memory and found some details on the bottom of my brain, I am not able to catch sharp picture, only general points left.
All of these projects have been very intersting, ... maybe some not, but anyway I missed such activity and even I came back again to power industry, as a couple of years I spent exploring automotive area but now I know that is too boring for me - daily routines in production... the same ones ...., I preffer to get new problems each day and fix them, with support of others if I am short of knowledge or experience.
So, I've thought of blog as a place to share what I am doing, to present projects I take part of or these ones which are driven by me.
All questions, notices, opinions are welcome. I think, would be good to give you a little amount of my personal info:
man, husband ,father, living in Europe, mechnical engineer from education. The English language is not my mother tongue, therefore please take it into account, if you suffer from my English, let me know what is wrong and I will correct this.
I am going to present my 3 projects, which were supervised by me
The first one is about reaction turbine repair, the 2nd, the smallest so far - bearing overhaul, in fact only, maching part of this activity (details will follow) and the 3rd one - very short overhaul of main internal parts of impulse turbine from Sugar Factory. I have several pictures and drawings, I hope these will help to understand what I am going to show.