Does anyone the what the correct torque pressure should be for keel bolts in a 1998 oceanis 352?
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keel bolt torque pressure
- Thread starter rockytopf
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Keel Bolt Torque
What size (diameter of bolt) and are they Stainless Steel?
With that info any machiene shop should be able to supply you with a torque value,also are the bolt threads lubricated? makes a difference in tourque values
What size (diameter of bolt) and are they Stainless Steel?
With that info any machiene shop should be able to supply you with a torque value,also are the bolt threads lubricated? makes a difference in tourque values
Here's standard torque values for metric profile stainless steel 18-8 bolts.
Suggest that you only torque to 80% of those values as these published values are for MAXIMUM torque.
Note - that the 'lubricated' values are for use with 30wt. oil applied to the threads. With lubricated values, tighten and un-tighten at least two times and then tighten to the 80% value for the final or 3rd torquing .... total torquing sequence is THREE TIMES.
http://www.fastenal.com/content/feds/pdf/Torque of Metric Stainless Steel.pdf
Suggest that you only torque to 80% of those values as these published values are for MAXIMUM torque.
Note - that the 'lubricated' values are for use with 30wt. oil applied to the threads. With lubricated values, tighten and un-tighten at least two times and then tighten to the 80% value for the final or 3rd torquing .... total torquing sequence is THREE TIMES.
http://www.fastenal.com/content/feds/pdf/Torque of Metric Stainless Steel.pdf
Shouldn't the torque value be dependent upon the material the bolt is being screwed into? I once stripped a steel bolt out of an aluminum engine block not being careful upon recaching the torque value.
Tejas has a point, although that should not be a huge issue with a cast iron keel. May be a slight concern with lead. There's always the old German approach. (Gutentite). Remember, that the attachment points in the hull could get crushed by overtorqueing too. The keel needs to be held onto the hull. The main forces will be lateral loading. It is not subjected to the same kinds of pressures that would be encountered in an engine cylinder head or crankshaft for example.
Such structure design most usually always includes a hefty safety factor - the expected dynamic stresses selected is one half to one third needed and the strength of materials used is always 2 to three times stronger than needed.
Simple speak - with boats, usually 'everything' is built/designed at 2 to 3+ times 'stronger' than they need to be for the intended normal service.
Inshore boats usually are built to a safety factor of 1.5 times greater than the maximum expected developed stresses; a coastal design at 2 times safety factor and an offshore design at a safety factor of 3 or more.
It's VERY poor engineering design practice to build for the exact limit of the material strengths and 'expected' stresses ... or a safety factor of "1".
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