During maintenance it is very difficult to open gas turbine bolts, specially of combustion section, turbine section and exhaust. Although power machines like hydraulic and pneumatics are available but even then many bolts break inside threads.

what is the good technique for opening these bolts?
what is good procedure to remove broken bolts? (conventional drill and tapping is not somehow affective)

 

Bolting problems.

On control.com.

Okay. I guess the Mechanical Department will ask anyone for help when they're desperate. The question is: Will they give credit where credit is due if the help proves valuable?

Do you use a quality anti-seize thread "lubricant", sometimes called "never-seize" or "never-seez" (I think the latter is a product name, possibly trademarked?)?

Is the anti-seize thread lubricant properly rated for the temperature and the metals of the application?

Do you use an excessive amount of anti-seize thread lubricant (too much of a good thing can be a problem)?

Do you use too much torque when reassembling bolts after a maintenance outage (again, too much of a good thing can be a problem)?

Some units were built in the factory and shipped with threaded inserts in what were deemed to be problem bolt locations. (A widely-use manufacturer of threaded inserts is Heli-coil; threaded inserts are also commonly called "heli-coils.") In general, threaded inserts can make it easier to remove a broken bolt because they "protect" the main threads when drilling out a broken bolt (they still usually have to be drilled out, though; there aren't many alternative to that).

This where the benefits of a hydraulic torque wrench are under-estimated. Not only are they useful for disassembling difficult bolts, many can be set for a particular torque value and used to quickly secure large numbers of bolts to a uniform torque value.

This is actually a good question for the company that supplies the bolts to replace the ones that failed. Along with an analysis of the bolts that are continually failing to see if they are the proper grade and material for the application! A good supplier, when asked for assistance with a problem like this, can usually make recommendations or assist with developing or finding a solution.

 

I think it may be funny for you. this type of question on this forum. but still I think is a problematic issue for each mechanical person,so I post.

Most of bolts for GT are installed with thread insert (heli coil) and anti sieze is also being used.

Did anyone know about "Gouging" and about laser drilling techniques for this purpose

 

You were asked if you used a quality anti-seize. There's anti-seize, and then there's anti-seize. There are purchasing and sourcing people ad managers who will buy the cheapest can of anti-seize they can buy without any regard for its temperature rating or the applicability of the material for the use it's needed for. They just bought three cases of this anti-seize for the price of one case of a better quality product that's more applicable for the application. But, they saved money--and that's their job and that's how their job performance is measured.

However, you didn't answer the question.

You were also asked if a torque wrench was used when re-assembling the unit, and you didn't respond to that, either.

If you've tried a better anti-seize and are using torque wrenches for reassembly, why didn't you tell us that in the original post? Why didn't you tell us what you've done to try to reduce the occurrence of broken bolts in the original post?

How is "gouging" or laser drilling going to make it unnecessary to have to remove a broken bolt?

You're not really interested in Root-Cause Analysis and reducing the occurrence of broken bolts that require additional effort (read: time and MONEY).

How is spending more money on extraction methods and equipment going to prevent the occurrence of broken bolts requiring extraction?

This is antiquated thinking at it's purest.

 

GT combustion chambers was first time disassembled at site. So all torquing and anit-sieze was originally installed at GT.

Even one combustion casing is also being replaced due to bolt broken problem.
once I remember that torquing was verified at site also.

Thanks

 

One way to remove is overheating the bolted head with some torch (flame, acetylene) and immediately use the hydraulic tool or some wrench you have.

To avoid this problem you must replace all bolting, replace heli colis and clean, use a quality anti-seize thread (3M maybe) according to the temperature and apply the correct value of torque using a torque wrench according to the size bolt.