Useful Life of Stainless Steel Hardware

[osirissail]

Besides all the care and maintenance considerations given by others - when it comes to stainless steel rigging the historical "10 year" useful life was predicated on the wire stretching. The loads on ss rigging are quite high and over the years the wire stretches enough that you have to periodically tighten the turnbuckles to maintain proper tension. Well eventually the wire becomes "really" stretched -not enough for you to see visually, but enough to make the wire brittle. Strands may break and then you get "fishhooks" or you run out of adjustment on the turnbuckles or the wire where it enters the swags in the terminal fitting corrodes and the wire breaks.
- - On average at about 10 years these problems become more prevalent and thusly, the 10 year useful life guideline was adopted. Individual boats in different geographical locations will have maybe longer life or shorter life. Inspections and tuning help keep you informed of the available life left in your rigging and when some parts need replacing.
- - In purchasing a used sailboat it is good to consider in the costs of replacing all the standing rigging wire and fittings if the boat is over 10 years old and has been used extensively.

[silverp40]

Thanks CGB for a lot of insightful information.

My friend works in a refinery as a welding instector and has a metal
tester that can tell what kind of metal alloy/composition a certain metal has. It is an expensive device about $45000 US plus a lot of samples that have to be "shot" first before pointing the unit at the metal in question to determine it's composition.

This is on way to determine metal make-up. This is also not really available to the average person so I guess we're stuck.

Chainplates that hold up our mast are important not to be active in places that are very difficult to be inspected. One reason I built ours of 316L, steel marked USA. They've been spot free for 9 years. I also inspect them every 2 years or so especially in the difficult areas.

Thanks again
Ovi

[silverp40]

The loads on ss rigging are quite high and over the years the wire stretches enough that you have to periodically tighten the turnbuckles to maintain proper tension. Well eventually the wire becomes "really" stretched

The deck and hull also move with the rigging tensioning...

[stillbuilding]

Hi Silverp40, Avesta have three or four products for use on welded stainless steel. There is a gel and a thicker paste. Different products for different stainless steels . Googel "Avesta pickling paste". I have used the gel which is brushed onto the weld and surrounds and left for a while before washing off with water. All the rusty contaminants seem to get removed so no issues later. I have used it with success on 316 rails, thick plate on deck fittings - no discolouration. TIG, MIG or stick all seem good although mostly use MIG/TIG

[osirissail]

There is a product called "Wichinox" by the Wichard company that specializes in stainless steel boat fittings. It does the same thing - dissolves the "stains" and passivates the SS a little. You need to use rubber gloves and a toothbrush to put it on and then a wet rag to remove it.

[silverp40]

Just wanted to ask one more question to the metalurgical experts, they have been more than helpful! Hope you do not mind:

We have 1/2" rods (I think they are Aquamet 19, Navtec uses that material for this application) that tie the base of the lower stays to the chainplates. These rods are therefore tensile loaded (lengthwise pull). They have been in the boat for 31 years and the boat has been sailed a lot. They look great, however - I do not see any discoloration (due to rust) and no cracks, fissures, crevice corrosion, IGC, etc.

Is there a time when metal reaches a point where it would be a good idea to replace even if there are no outward signs of fatigue?

Thanks again to all, this thread has been GREAT!!
Ovi

PS Wichinox has worked well for us in passivating steel. Thanks osirissail.

[osirissail]

Cracks in metal fittings are not usually visible to the naked eye until it is almost too late. You can obtain a "Dye Check" kit from outfits that sell to experimental airplane builders and then use the kit to determine whether there really are any cracks in your metal fittings. I have done this and found a lengthwise crack in a swagged terminal fitting that was not visible to the unaided eye.
- - With "rod" rigging the usual place for cracks is at the ball fittings which attach the rod to the mast and likewise at the other end, to the chain plates. As the sailboat with rod rigging moves the ball and socket constantly grind against each other. Watching this area for excessive wear should be high up on your inspection list.