Bolting Question

[Outback101]

I work in a power plant and we often have trouble with large bolting galling or seizing up especially during disassembly. It looks like most of the bolting was assembled with no type of dry or paste anti-seize. I understand the high temps encountered and that lubricating the threads can effect torquing of fasteners or using the wrong type may cause more problems than solving if it turns to carbon, hardens, etc.. Most of our critical bolting is checked for stretch though and not specific torque value. Why the apparent use of no lubricants, break free, or other magical elixirs to aid in disassembly or assembly for that matter. Seems better than ending up using large nut splitters and replacing galled studs, etc.?

 

[EdStainless]

Because that is how they have always done it.
In some applications there is not a good anti-seize to use, and using the wrong one is a disaster.

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P.E. Metallurgy, Plymouth Tube

 

[metengr]

Typically, large bolts will be on turbine shells, valve bonnets and flanges, which will go years before disassembly. Our maintenance group at the various Power Plants I worked at and visited for many years used WD-40 or PT cleaner right before disassembly by soaking for several hours and most of the time it worked.

 

[r6155]

Outback101. Please, can you tell us the bolt diameter and service temperature?. Are the bolts coated?. Material of bolts and nuts?

Regards
r6155

 

[Outback101]

The studs are 2"dia., 8 thread, B16 material. Coating unknown if any. They are being used on a large steam valve so its hot and high.

 

[Outback101]

I would think that Kroil/Wd40/PB blaster or similar would be part disassembly to help avoid the galling. Some sort of dry lube for assembly

 

[r6155]

See MOLYKOTE productc for disassembly "MULTIGLISS" and pre-assembly "1000"

Regards
r6155

 

[r6155]

Outback101. I can see in your picture marking 2H on nuts.
Where is the documentation of the valve?.
Please, search a complete information and then tell us (service temperature, washer material, etc ).

Regards
r6155