heating 5/16" shrouds

[berwick]

I have seized bolts that hold the end the spreader together (the old aluminum spreader and SS bolts) I cannot remove them and the SS wire is not moving through the ends of the spreader because of the corrosion. I would like to apply heat to the bolts but am worried about this heat transferring from the bolts to the 5/16" wire and weakening or tempering the wire. How much of a worry is this? Can it take some heat?

Thanks, Richard

[Douglas]

Were you going to use a air blower heat gun, of a flame blow torch ?

Once I read that heating ss above 400 degrees F , could change some of it's resistance to corrosion properties.

What kind of corrosion are you talking about ? The white powder kind from the aluminum, or the rusting kind from the ss ?

I clean the rusting kind from my ss with a ss pickling paste, but was never sure just what to use on the aluminum white powder.

Would any rigger out there use a lye solution on the aluminum, to desolve the white powder kind of corrosion that aluminum gets ?

A Lye solution is used to dip aluminum into, before washing, then going to an anodizing tank .

Has anyone tried re-anodizing a spot area, or a deep scratch area ?

Some say that you can not re-anodize aluminum, but I am not sure that is true, if you can remove all the old anodizing, and get back to base metal.

I have often wondered what would happen if I used the ss pickling paste on aluminum,,,, that paste is a combo of Nitric, Hydroflouric, and Phosphoric acids in a thickened solution.

I have used the ss pickling paste on bronze, and that cleans it very well, but it works best on ss to remove rust, and surface contaminants that corrode ss which results in pitting.

Don't get ss pickling paste on your paint, as that will "half life" that paint,,,, and don't get it on yourself, as that will eat your skin away to the bone.

Winchinox is similar to ss pickling paste .

Use any acid with extreem caution, until you can reliably predict the reactions .

Douglas

[berwick]

I was just thinking of using a paint stripper gun, but still don't know know how bad this is on the SS wiring. Is there any books that would give this type of info?

Richard

[Clyde Jenkins]

Some technical stuff:
304 and 316 stainless are hardened by cold working through processes like drawing the material into wire. The cold working improves some of the properties like tensile strength. Annealing the wire with heat will lose that gain in strength.

304 stainless is annealed at a temperature of 1010 to 1120 degrees C (roughly 1850 deg F). It is stress relieved at a temperature of 400 deg. C (or roughly 750 deg F).

316 stainless is annealed in the same temperature range. It is stress relieved in a range of 200 to 400 degrees C (or roughly 390 to 750 deg F).

Sources: http://www.askzn.co.za/tech/tech_grade_304.htm
http://www.askzn.co.za/tech/tech_grade_316.htm

You might want to call a wire rope manufacturer like Loos http://www.loosco.com/Contact.htm
to see whether stress relieving will be a problem. I don't think you want to anneal the wire.

Frozen parts are frustrating. Here are some tricks I've used:

1. Chemistry -- My new favorite penetrating oil is PB Blaster. I got it at a NAPA auto parts store. It may be available at Home Depot or Lowe's.

2. Heat -- If you get a definitive answer on max temperature, you can go to a welding supply store and buy a Tempil-stick crayon for that (or some slightly lower) temperature. Color the crayon on your part before or during heating. It will melt when you reach the temperature.

Your hot air gun should not be a problem. I doubt you'll get the parts much above the temp required to boil water. The aluminum has a higher coefficient of thermal expansion that the stainless and that may help loosen the bolts. Be careful mixing chemistry and heat. The chemicals are flammable. Burning off the oil may not be bad but you want to be in a well ventilated place and you don't want anything else to catch fire.

I hope your rig is out of the boat. Playing with torches and high temperature tools is a dicey business when you're hanging from a polyester halyard.

3. Force -- You can buy an impact driver. It looks like a beefy screw driver with a socket drive on one end. Get a six point socket (or an impact wrench socket) the right size for your bolts. You put the driver on the bolt and twist in the direction you want to go and whack the driver with a hammer or a mallet.

You can increase the leverage of your wrench with a pipe or by slipping the hole in the handle of a big crescent wrench over the handle of your socket or combination wrench. I don't trust crescent wrenches for high torque problems, so I use a socket or a box end wrench on the problem bolt. (The crescent wrench is just used for a leverage multiplier. You can also slip a larger box end wrench over the handle of the socket or combination wrench.)

Have a backup plan. What will you do if you snap the head off a bolt? If the consequence of that is too expensive, be very careful about high torque solutions.

Be patient (this may take treatments over several days). Be careful. Good luck.

Clyde