what do we to handel bolt connection in pedestal of cement pumping truck

quote:

AVILUB METACON907

I found the following information on the internet. When using an oil, the friction on the bolt will be lower. The torque used on the bolt can be increased to tighten the bolt. When a product with good lubricating properties, the momentum (torque) should be adjused to avoid damaging of the bolts.
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Non-water-soluble cooling lubricants

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why not use oil paste such as molykote 1000/ P74 to lubricate bolt , and you know , bolt paste is good to use in such case to keep torque to avoid bolt damage,
generlly , bolts in this equipment should be re-tighten every 500h , so bolt paste is very suitable for the use . but i donot why they still use oil to lubricat????

I suggest Molykote 1000/P74/P37 to be applied if it is high temperature application. Product will prevent seizures even at high temperature up to 1500 deg.
If you just want to reduce torque you can use G rapid paste which has coeff of friction as low as .06

AVOID USING A PASTE WITH MOLYBDENUM DISULFIDE !
THe torque reduction of perhaps 30% caused by the moly paste will cause a higher tightening than permissible and then the additional elongation of the screw may cause it to break. I have seen that in the past.

Only use metallic paste for example based on copper or a silver paste, but without moly or graphite.

thanks all, but i still want to make sure how about the tribology difference in bolt lubrication between oil and paste , pls give some idea,,,

quote:

perhaps 30% caused by the moly paste will cause a higher tightening than permissible and then the additional elongation of the screw may cause it to break. I have seen that in the past.

*Only use metallic paste for example based on copper or a silver paste, but without moly or graphite.

*

Use Molykote Copper Paste in this situation.

Difference is Paste will have oil and solid lubricant/metal particles. oil will squeeze out with pressure while solid lubes will settle in the pores and minute cavities thus provide lubrication throught out.

"When using an oil, the friction on the bolt will be lower"

When we run into this area of high case pressures and lubricated bolt tightening torque containing the pressure bolt elongation measurements will provide the correct pressure if unsure of the effects of different lubricants on the tightening torque,
The manufacturer can provide the correct elongation of the holding bolts and the bolts tightened until the correct measurement of elongation is achieved with the tightening torque a secondary measurement,
This removes the difficulty of calculating the effect of differing thread lubricants whilst ensuring correct pressure on the item being held by the bolts.
This may not be possible due to design in some instances but the pressures generated concrete pumps are high and care must be taken when working on high pressure equipment.

Regards


Rob S