heating 5/16" shrouds

[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